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Source: https://theconversation.com/us/topics/astronomy-50/articles.atom

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6.  <title>Astronomy – The Conversation</title>
7.  <updated>2025-07-04T02:16:18Z</updated>
8.  <entry>
9.    <id>tag:theconversation.com,2011:article/260422</id>
10.    <published>2025-07-04T02:16:18Z</published>
11.    <updated>2025-07-04T02:16:18Z</updated>
12.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomers-have-spied-an-interstellar-object-zooming-through-the-solar-system-260422"/>
13.    <title>Astronomers have spied an interstellar object zooming through the Solar System</title>
14.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/678264/original/file-20250704-56-ajzgow.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C215%2C2403%2C1351&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://deeprandomsurvey.org/"&gt;K Ly / Deep Random Survey&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;This week, astronomers spotted the third known interstellar visitor to our Solar System.&lt;/p&gt;
15.  
16. <p>First detected by the <a href="https://en.wikipedia.org/wiki/Asteroid_Terrestrial-impact_Last_Alert_System">Asteroid Terrestrial-impact Last Alert System (ATLAS)</a> on July 1, the cosmic interloper was given the temporary name A11pl3Z. Experts at NASA’s Center for Near Earth Object Studies and the International Astronomical Union (IAU) have confirmed the find, and the object now has an official designation: I3/ATLAS. </p>
17.  
18. <figure class="align-center zoomable">
19.            <a href="https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of the Solar System out to Jupiter detailing the path of interstellar object I3/ATLAS." src="https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/678167/original/file-20250703-56-69zch4.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
20.            <figcaption>
21.              <span class="caption">The orbital path of I3/ATLAS through the Solar System.</span>
22.              <span class="attribution"><a class="source" href="https://assets.science.nasa.gov/dynamicimage/assets/science/psd/planetary-defense/3I_interstellar%20comet%20orbit.jpg?w=1840&h=1200&fit=clip&crop=faces%2Cfocalpoint">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
23.            </figcaption>
24.          </figure>
25.  
26. <p>There are a few strong clues that suggest 3I/ATLAS came from outside the Solar System. </p>
27.  
28. <p>First, it’s moving really fast. <a href="https://minorplanetcenter.net/mpec/K25/K25N12.html">Current observations</a> show it speeding through space at around 245,000km per hour. That’s more than enough to escape the Sun’s gravity. </p>
29.  
30. <p>An object near Earth’s orbit would only need to be travelling at just over 150,000km/h to break free from the Solar System.</p>
31.  
32. <p>Second, 3I/ATLAS has a wildly eccentric orbit around the Sun. Eccentricity measures how “stretched” an orbit is: 0 eccentricity is a perfect circle, and anything up to 1 is an increasingly strung-out ellipse. Above 1 is an orbit that is not bound to the Sun.</p>
33.  
34. <p>3I/ATLAS has an estimated eccentricity of 6.3, by far the highest ever recorded for any object in the Solar System.</p>
35.  
36. <h2>Has anything like this happened before?</h2>
37.  
38. <figure class="align-center zoomable">
39.            <a href="https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's impression of the first confirmed interstellar object, 1I/'Oumuamua." src="https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/678168/original/file-20250703-68-brg8fd.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
40.            <figcaption>
41.              <span class="caption">An artist’s impression of the first confirmed interstellar object, 1I/‘Oumuamua.</span>
42.              <span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1737a/">ESO/M. Kornmesser</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
43.            </figcaption>
44.          </figure>
45.  
46. <p>The first interstellar object spotted in our Solar System was the cigar-shaped <a href="https://en.wikipedia.org/wiki/1I/%CA%BBOumuamua">‘Oumuamua</a>, discovered in 2017 by the Pan-STARRS1 telescope in Hawaii. Scientists tracked it for 80 days before eventually confirming it came from interstellar space.</p>
47.  
48. <figure class="align-center zoomable">
49.            <a href="https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The interstellar comet I2/Borisov, imaged by the Hubble Space Telescope." src="https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/678169/original/file-20250703-56-jdfriz.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
50.            <figcaption>
51.              <span class="caption">The interstellar comet I2/Borisov, imaged by the Hubble Space Telescope.</span>
52.              <span class="attribution"><a class="source" href="https://esahubble.org/images/heic1918a/">NASA, ESA, and D. Jewitt (UCLA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
53.            </figcaption>
54.          </figure>
55.  
56. <p>The second interstellar visitor, comet <a href="https://en.wikipedia.org/wiki/2I/Borisov#Observation">2I/Borisov</a>, was discovered two years later by amateur astronomer Gennadiy Borisov. This time it only took astronomers a few weeks to confirm it came from outside the Solar System.</p>
57.  
58. <p>This time, the interstellar origin of I3/ATLAS has been confirmed in a matter of days.</p>
59.  
60. <h2>How did it get here?</h2>
61.  
62. <p>We have only ever seen three interstellar visitors (including I3/ATLAS), so it’s hard to know exactly how they made their way here.</p>
63.  
64. <p>However, <a href="https://iopscience.iop.org/article/10.3847/PSJ/adb1e9">recent research</a> published in The Planetary Science Journal suggests these objects might be more common than we once thought. In particular, they may come from relatively nearby star systems such as Alpha Centauri (our nearest interstellar neighbour, a mere 4.4 light years away).</p>
65.  
66. <figure class="align-center zoomable">
67.            <a href="https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two bright stars of the Alpha Centauri triple star system." src="https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/678173/original/file-20250703-56-3s74ub.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
68.            <figcaption>
69.              <span class="caption">Alpha Centauri A and Alpha Centauri B, from the triple star system Alpha Centauri.</span>
70.              <span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1629v/">ESA/Hubble & NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
71.            </figcaption>
72.          </figure>
73.  
74. <p><a href="https://en.wikipedia.org/wiki/Alpha_Centauri">Alpha Centauri</a> is slowly moving closer to us, with its closest approach expected in about 28,000 years. If it flings out material in the same way our Solar System does, scientists estimate around a million objects from Alpha Centauri larger than 100 metres in diameter could already be in the outer reaches of our Solar System. That number could increase tenfold as Alpha Centauri gets closer.</p>
75.  
76. <p>Most of this material would have been ejected at relatively low speeds, less than 2km/s, making it more likely to drift into our cosmic neighbourhood over time and not dramatically zoom in and out of the Solar System like I3/ATLAS appears to be doing. While the chance of one of these objects coming close to the Sun is extremely small, the study suggests a few tiny meteors from Alpha Centauri, likely no bigger than grains of sand, may already hit Earth’s atmosphere every year. </p>
77.  
78. <h2>Why is this interesting?</h2>
79.  
80. <p>Discovering new interstellar visitors like 3I/ATLAS is thrilling, not just because they’re rare, but because each one offers a unique glimpse into the wider galaxy. Every confirmed interstellar object expands our catalogue and helps scientists better understand the nature of these visitors, how they travel through space, and where they might have come from.</p>
81.  
82. <figure>
83.            <iframe width="440" height="260" src="https://www.youtube.com/embed/DTuq-vBsDJE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
84.            <figcaption><span class="caption">A swarm of new asteroids discovered by the NSF–DOE Vera C. Rubin Observatory.</span></figcaption>
85.          </figure>
86.  
87. <p>Thanks to powerful new observatories such as the <a href="https://rubinobservatory.org/">NSF–DOE Vera C. Rubin Observatory</a>, our ability to detect these elusive objects is rapidly improving. In fact, during its first 10 hours of test imaging, Rubin <a href="https://rubinobservatory.org/news/rubin-first-look/swarm-asteroids">revealed 2,104 previously unknown asteroids</a>. </p>
88.  
89. <p>This is an astonishing preview of what’s to come. With its wide field of view and constant sky coverage, Rubin is expected to revolutionise our search for interstellar objects, potentially turning rare discoveries into routine ones.</p>
90.  
91. <h2>What now?</h2>
92.  
93. <p>There’s still plenty left to uncover about 3I/ATLAS. Right now, it’s officially classified as a comet by the IAU Minor Planet Center. </p>
94.  
95. <p>But some scientists argue it <a href="https://phys.org/news/2025-07-inbound-astronomers-interstellar.html">might actually be an asteroid</a>, roughly 20km across, based on the lack of typical comet-like features such as a glowing coma or a tail. More observations will be needed to confirm its nature.</p>
96.  
97. <p>Currently, 3I/ATLAS is inbound, just inside Jupiter’s orbit. It’s expected to reach its closest point to the Sun, slightly closer than the planet Mars, on October 29. After that, it will swing back out towards deep space, making its closest approach to Earth in December. (It will pose no threat to our planet.)</p>
98.  
99. <p>Whether it’s a comet or an asteroid, 3I/ATLAS is a messenger from another star system. For now, these sightings are rare – though as next-generation observatories such as Rubin swing into operation, we may discover interstellar companions all around.</p><img src="https://counter.theconversation.com/content/260422/count.gif" alt="The Conversation" width="1" height="1" />
100. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Kirsten Banks does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
101.    <summary>An object dubbed 3I/ATLAS is only the third interloper from outside the Solar System seen in all of human history.</summary>
102.    <author>
103.      <name>Kirsten Banks, Lecturer, School of Science, Computing and Engineering Technologies, Swinburne University of Technology</name>
104.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/kirsten-banks-2278823"/>
105.    </author>
106.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
107.  </entry>
108.  <entry>
109.    <id>tag:theconversation.com,2011:article/257421</id>
110.    <published>2025-06-30T12:31:18Z</published>
111.    <updated>2025-06-30T12:31:18Z</updated>
112.    <link rel="alternate" type="text/html" href="https://theconversation.com/how-can-the-james-webb-space-telescope-see-so-far-257421"/>
113.    <title>How can the James Webb Space Telescope see so far?</title>
114.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/672026/original/file-20250603-56-52fim0.png?ixlib=rb-4.1.0&amp;amp;rect=0%2C517%2C4159%2C2339&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;This is a James Webb Space Telescope image of NGC 604, a star-forming region about 2.7 million light-years from Earth.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://webbtelescope.org/contents/media/images/2024/110/01HQNV4GP6PR6E7ZSJXRRBQQDS?page=1&amp;amp;filterUUID=91dfa083-c258-4f9f-bef1-8f40c26f4c97"&gt;NASA/ESA/CSA/STScI&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;
115.  
116. <p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>.</em></p>
117.  
118. <hr>
119.  
120. <blockquote>
121. <p><strong>How does the camera on the James Webb Space Telescope work and see so far out? – Kieran G., age 12, Minnesota</strong></p>
122. </blockquote>
123.  
124. <hr>
125.  
126. <p>Imagine a camera so powerful it can see light from galaxies that formed more than <a href="https://science.nasa.gov/mission/webb/webbs-mirrors/">13 billion years ago</a>. That’s exactly what NASA’s James Webb Space Telescope is built to do. </p>
127.  
128. <p>Since it launched in <a href="https://science.nasa.gov/mission/webb/launch/">December 2021</a>, Webb has been orbiting more than a million miles from Earth, capturing breathtaking images of deep space. But how does it actually work? And how can it see so far? The secret lies in its powerful cameras – especially ones that don’t see light the way our eyes do.</p>
129.  
130. <p><a href="https://scholar.google.com/citations?user=iBT78yoAAAAJ&hl=en">I’m an astrophysicist</a> who studies galaxies and supermassive black holes, and the Webb telescope is an incredible tool for observing some of the earliest galaxies and black holes in the universe.</p>
131.  
132. <p>When Webb takes a picture of a distant galaxy, astronomers like me are actually seeing what that galaxy looked like billions of years ago. The light from that galaxy has been traveling across space for the billions of years it takes to reach the telescope’s mirror. It’s like having a time machine that takes snapshots of the early universe.</p>
133.  
134. <p>By using a giant mirror to collect ancient light, Webb has been discovering new secrets about the universe.</p>
135.  
136. <h2>A telescope that sees heat</h2>
137.  
138. <p>Unlike regular cameras or even the Hubble Space Telescope, which take images of visible light, Webb is designed to see a kind of light that’s invisible to your eyes: <a href="https://science.nasa.gov/ems/07_infraredwaves/">infrared light</a>. Infrared light has longer wavelengths than visible light, which is why our eyes can’t detect it. But with the right instruments, Webb can capture infrared light to study some of the earliest and most distant objects in the universe.</p>
139.  
140. <figure class="align-center zoomable">
141.            <a href="https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dog, shown normally, then through thermal imaging, with the eyes, mouth and ears brighter than the rest of the dog." src="https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/672020/original/file-20250603-56-afzvl4.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
142.            <figcaption>
143.              <span class="caption">Infrared cameras, like night-vision goggles, allow you to ‘see’ the infrared waves emitting from warm objects such as humans and animals. The temperatures for the images are in degrees Fahrenheit.</span>
144.              <span class="attribution"><span class="source">NASA/JPL-Caltech</span></span>
145.            </figcaption>
146.          </figure>
147.  
148. <p>Although the human eye cannot see it, people can detect infrared light as a form of heat using specialized technology, such as infrared cameras or thermal sensors. For example, night-vision goggles use infrared light to detect warm objects in the dark. Webb uses the same idea to study stars, galaxies and planets.</p>
149.  
150. <p>Why infrared? When visible light from faraway galaxies travels across the universe, <a href="https://www.skyatnightmagazine.com/space-science/redshift">it stretches out</a>. This is because the <a href="https://theconversation.com/where-is-the-center-of-the-universe-252695">universe is expanding</a>. That stretching turns visible light into infrared light. So, the most distant galaxies in space don’t shine in visible light anymore – they glow in faint infrared. That’s the light Webb is built to detect. </p>
151.  
152. <figure class="align-center zoomable">
153.            <a href="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of the electromagnetic spectrum, with radio, micro and infrared waves having a longer wavelength than visible light, while UV, X-ray and gamma rays have shorter wavelengths than visible light." src="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=356&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=356&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=356&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=447&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=447&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=447&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
154.            <figcaption>
155.              <span class="caption">The rainbow of visible light that you can see is only a small slice of all the kinds of light. Some telescopes can detect light with a longer wavelength, such as infrared light, or light with a shorter wavelength, such as ultraviolet light. Others can detect X-rays or radio waves.</span>
156.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Electromagnetic_spectrum#/media/File:EM_Spectrum_Properties_edit.svg">Inductiveload, NASA/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
157.            </figcaption>
158.          </figure>
159.  
160. <h2>A golden mirror to gather the faintest glow</h2>
161.  
162. <p>Before the light reaches the cameras, it first has to be collected by the Webb telescope’s <a href="https://www.nasa.gov/image-article/james-webb-space-telescopes-golden-mirror/">enormous golden mirror</a>. This mirror is over 21 feet (6.5 meters) wide and made of 18 smaller mirror pieces that fit together like a honeycomb. It’s coated in a thin layer of real gold – not just to look fancy, but because gold reflects infrared light extremely well. </p>
163.  
164. <p>The mirror gathers light from deep space and reflects it into the telescope’s instruments. The <a href="https://theconversation.com/how-do-you-build-a-mirror-for-one-of-the-worlds-biggest-telescopes-49927">bigger the mirror</a>, the more light it can collect – and the farther it can see. Webb’s mirror is the largest ever launched into space.</p>
165.  
166. <figure class="align-center zoomable">
167.            <a href="https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The JWST's mirror, which looks like a large, roughly hexagonal shiny surface made up of 18 smaller hexagons put together, sitting in a facility. The mirror is reflecting the NASA meatball logo." src="https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/672021/original/file-20250603-68-pimc7g.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
168.            <figcaption>
169.              <span class="caption">Webb’s 21-foot primary mirror, made of 18 hexagonal mirrors, is coated with a plating of gold.</span>
170.              <span class="attribution"><span class="source">NASA</span></span>
171.            </figcaption>
172.          </figure>
173.  
174. <h2>Inside the cameras: NIRCam and MIRI</h2>
175.  
176. <p>The most important “eyes” of the telescope are two science instruments that act like cameras: NIRCam and MIRI.</p>
177.  
178. <p>NIRCam stands for near-infrared camera. It’s the primary camera on Webb and takes stunning images of galaxies and stars. It also has <a href="https://www.space.com/what-is-a-coronagraph.html">a coronagraph</a> – a device that blocks out starlight so it can photograph very faint objects near bright sources, such as planets orbiting bright stars. </p>
179.  
180. <p><a href="https://science.nasa.gov/mission/webb/nircam/">NIRCam works by imaging near-infrared light</a>, the type closest to what human eyes can almost see, and splitting it into different wavelengths. This helps scientists learn not just what something looks like but what it’s made of. Different materials in space absorb and emit infrared light at specific wavelengths, creating a kind of unique <a href="https://theconversation.com/accelerating-exoplanet-discovery-using-chemical-signatures-of-stars-118818">chemical fingerprint</a>. By studying these fingerprints, scientists can uncover the properties of distant stars and galaxies. </p>
181.  
182. <p>MIRI, or the mid-infrared instrument, <a href="https://science.nasa.gov/mission/webb/mid-infrared-instrument-miri/">detects longer infrared wavelengths</a>, which are especially useful for spotting cooler and dustier objects, such as stars that are still forming inside clouds of gas. MIRI can even help find clues about the types of molecules in the atmospheres of <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">planets that might support life</a>.</p>
183.  
184. <p>Both cameras are far more sensitive than the standard cameras used on Earth. NIRCam and MIRI can detect the tiniest amounts of heat from billions of light-years away. If you had Webb’s NIRCam as your eyes, you could see the heat from a bumblebee on the Moon. That’s how sensitive it is. </p>
185.  
186. <figure class="align-center zoomable">
187.            <a href="https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two photos of space, with lots of stars and galaxies shown as little dots. The right image shows more, brighter dots than the left." src="https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/672022/original/file-20250603-62-caxykh.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
188.            <figcaption>
189.              <span class="caption">Webb’s first deep-field image: The MIRI image is on the left and the NIRCam image is on the right.</span>
190.              <span class="attribution"><span class="source">NASA</span></span>
191.            </figcaption>
192.          </figure>
193.  
194. <p>Because Webb is trying to detect faint heat from faraway objects, it needs to keep itself as cold as possible. That’s why it carries <a href="https://science.nasa.gov/mission/webb/webbs-sunshield/">a giant sun shield about the size of a tennis court</a>. This five-layer sun shield blocks heat from the Sun, Earth and even the Moon, helping Webb stay incredibly cold: around -370 degrees F (-223 degrees C). </p>
195.  
196. <p>MIRI needs to be even colder. It has its own special refrigerator, called a cryocooler, to keep it chilled to nearly -447 degrees F (-266 degrees C). If Webb were even a little warm, its own heat would drown out the distant signals it’s trying to detect.</p>
197.  
198. <h2>Turning space light into pictures</h2>
199.  
200. <p>Once light reaches the Webb telescope’s cameras, it hits sensors called detectors. <a href="https://science.nasa.gov/mission/webb/infrared-detectors/">These detectors</a> don’t capture regular photos like a phone camera. Instead, they convert the incoming infrared light into digital data. That data is then sent back to Earth, where scientists process it into <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">full-color images</a>.</p>
201.  
202. <p>The colors we see in Webb’s pictures aren’t what the camera “sees” directly. Because infrared light is invisible, scientists assign colors to different wavelengths to help us understand what’s in the image. These processed images help show the structure, age and composition of galaxies, stars and more.</p>
203.  
204. <p>By using a giant mirror to collect invisible infrared light and sending it to super-cold cameras, Webb lets us see galaxies that formed just after the universe began.</p>
205.  
206. <hr>
207.  
208. <p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
209.  
210. <p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/257421/count.gif" alt="The Conversation" width="1" height="1" />
211. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Adi Foord does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
212.    <summary>The James Webb Space Telescope has 2 powerful instruments that see light the human eye can’t.</summary>
213.    <author>
214.      <name>Adi Foord, Assistant Professor of Astronomy and Astrophysics, University of Maryland, Baltimore County</name>
215.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/adi-foord-1472117"/>
216.    </author>
217.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
218.  </entry>
219.  <entry>
220.    <id>tag:theconversation.com,2011:article/259857</id>
221.    <published>2025-06-27T13:10:15Z</published>
222.    <updated>2025-06-27T13:10:15Z</updated>
223.    <link rel="alternate" type="text/html" href="https://theconversation.com/could-the-first-images-from-the-vera-rubin-telescope-change-how-we-view-space-for-good-259857"/>
224.    <title>Could the first images from the Vera Rubin telescope change how we view space for good?</title>
225.    <content type="html">&lt;p&gt;We are entering a new era of cosmic exploration. The new &lt;a href="https://rubinobservatory.org/"&gt;Vera C Rubin Observatory&lt;/a&gt; in Chile will transform astronomy with its extraordinary ability to map the universe in breathtaking detail. It is set to reveal secrets previously beyond our grasp. Here, we delve into the first images taken by Rubin’s telescope and what they are already showing us.&lt;/p&gt;
226.  
227. <p>These images vividly showcase the unprecedented power that Rubin will use to
228. revolutionise astronomy and our understanding of the Universe. Rubin is truly transformative, thanks to its unique combination of sensitivity, vast sky area coverage and exceptional image quality. </p>
229.  
230. <p>These pictures powerfully demonstrate those attributes. They reveal not only bright objects in exquisite detail but also faint structures, both near and far, across a large area of sky.</p>
231.  
232. <h2>Cosmic nurseries – nebulae in detail</h2>
233.  
234. <p>The stunning <a href="https://rubinobservatory.org/news/rubin-first-look/trifid-lagoon">pink and blue clouds</a> in this image are the Lagoon (lower left) and Trifid (upper right) nebulae. The word nebula comes from the Latin for cloud, and these giant clouds are truly enormous – so vast it takes light decades to travel across them. They are stellar nurseries, the very birth sites for the next generation of stars and planets in our Milky Way galaxy.</p>
235.  
236. <p>The intense radiation from hot, young stars energises the gas particles, causing
237. them to glow pink. Further from these nascent stars, colder regions consist of
238. microscopic dust grains. These reflect starlight (a process known in astronomy as
239. “scattering”), much like our atmosphere, creating the beautiful blue hues. Darker filaments within are much denser regions of dust, obscuring all but the brightest background stars.</p>
240.  
241. <p>To detect these colours, astronomers use filters over their instruments, allowing only certain wavelengths of light onto the detectors. Rubin has six such filters, spanning from short ultraviolet (UV) wavelengths through the visible spectrum to longer near-infrared light. Combining information from these different filters enables detailed measurements of the properties of stars and gas, such as their temperature and size.</p>
242.  
243. <p>Rubin’s speed – its ability to take an image with one filter and then quickly move to the next – combined with the sheer area of sky it can see at any one time, is what makes it so unique and so exciting. The level of detail, revealing the finest and faintest structures, will enable it to map the substructure and satellite galaxies of the Milky Way like never before.</p>
244.  
245. <h2>Mapping galaxies across billions of light years</h2>
246.  
247. <figure class="align-center ">
248.            <img alt="" src="https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/676637/original/file-20250625-56-30x25f.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
249.            <figcaption>
250.              <span class="caption">This image captures a small section of NSF–DOE Vera C. Rubin Observatory’s view of the Virgo Cluster, offering a vivid glimpse of the variety in the cosmos.</span>
251.              <span class="attribution"><a class="source" href="https://rubinobservatory.org/gallery/collections/first-look-gallery/32ejonfcf955v6luvhdvbd746c">Credit: NSF–DOE Vera C. Rubin Observatory</a></span>
252.            </figcaption>
253.          </figure>
254.  
255. <p>The images of galaxies powerfully demonstrate the scale at which the Rubin
256. observatory will map the universe beyond our own Milky Way. The large galaxies
257. visible here (such as the two bright spiral shaped galaxies visible in the lower right quarter of the picture) belong to the <a href="https://rubinobservatory.org/news/rubin-first-look/cosmic-treasure-chest">Virgo cluster</a>, a giant structure containing more than 1,000 galaxies, each holding billions to trillions of stars.</p>
258.  
259. <p>This image beautifully showcases the huge diversity of shapes, sizes and colours of galaxies in our universe revealed by Rubin in their full technicolour glory. Inside these galaxies, bright dots are visible – these are star-forming regions, just like the Lagoon and Trifid nebulae, but remarkably, these are millions of light years away from us. </p>
260.  
261. <p>The still image captures just 2% of the area of a full Rubin image revealing a universe that is teeming with celestial bodies. The full image, which contains around ten million galaxies, would need several hundred ultra high-definition TV screens to display in all its detail. By the end of its ten-year survey, Rubin will catalogue the properties of some 20 billion galaxies, their colours and locations on the sky containing information about even more mysterious components of our universe such as dark matter and dark energy. Dark matter makes up most of the matter in the cosmos, but does not reflect or emit light. Dark energy seems to be responsible for the accelerating expansion of the universe.</p>
262.  
263. <h2>The UK’s role</h2>
264.  
265. <p>These unfathomable numbers demand data processing on a whole new scale.
266. Uncovering new discoveries from this data requires a giant collaborative effort, in which UK astronomy is playing a major role. The UK will process around 1.5 million Rubin images and hosts one of three international data access centres for the project, providing scientists across the globe with access to the vast Rubin data. Here at the University of Southampton, we are leading two critical software
267. development contributions to Rubin. </p>
268.  
269. <p>First of these is the capability to combine the Rubin images with those at longer infrared wavelengths. This extends the colours that Rubin sees, providing key diagnostic information about the properties of stars and galaxies. Second is the software that will link Rubin observations to another new instrument <a href="https://www.4most.eu/cms/home/">called 4MOST</a>, soon to be installed at the Vista telescope in Chile.</p>
270.  
271. <p>Part of 4MOST’s job will be to snap up and classify rapidly changing “sources”, or objects, in the sky that have been discovered by Rubin. One such type of rapidly changing source is a stellar explosion known <a href="https://esahubble.org/wordbank/supernova/">as a supernova</a>. We expect to have catalogued more supernova explosions within just two years than have ever been made previously. Our contributions to the Rubin project will therefore lead to a totally new understanding of how the stars and galaxies in our universe live and die, offering an unprecedented glimpse into the grand cosmic cycle.</p>
272.  
273. <p>The Rubin observatory isn’t just a new telescope – it’s a new pair of eyes on the
274. universe, revealing the cosmos in unprecedented detail. A treasure trove of
275. discoveries await, but most interesting among them will be the hidden secrets of the universe that we are yet to contemplate. The first images from Rubin have been a spectacular demonstration of the vastness of the universe. What might we find in
276. this gargantuan dataset of the cosmos as the ultimate timelapse movie of our
277. universe unfolds?</p><img src="https://counter.theconversation.com/content/259857/count.gif" alt="The Conversation" width="1" height="1" />
278. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Professor Manda Banerji receives funding from the Royal Society and the Science and Technology Facilities Council. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Dr Philip Wiseman receives funding from the Science and Technology Facilities Council&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
279.    <summary>The new observatory can take very high resolution images of distant objects in space.</summary>
280.    <author>
281.      <name>Professor Manda Banerji, Professor of Astrophysics, School of Physics &amp; Astronomy, University of Southampton</name>
282.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/professor-manda-banerji-2421335"/>
283.    </author>
284.    <author>
285.      <name>Dr Phil Wiseman, Research Fellow, Astronomy, University of Southampton</name>
286.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/dr-phil-wiseman-1513455"/>
287.    </author>
288.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
289.  </entry>
290.  <entry>
291.    <id>tag:theconversation.com,2011:article/249834</id>
292.    <published>2025-06-25T12:44:16Z</published>
293.    <updated>2025-06-25T12:44:16Z</updated>
294.    <link rel="alternate" type="text/html" href="https://theconversation.com/how-do-scientists-calculate-the-probability-that-an-asteroid-could-hit-earth-249834"/>
295.    <title>How do scientists calculate the probability that an asteroid could hit Earth?</title>
296.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/668461/original/file-20250516-62-wffqck.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C56%2C950%2C534&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;NASA&amp;#39;s Webb telescope captured a photo of the asteroid 2024 YR4 from afar. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://newsroom.ap.org/detail/NewlyDiscoveredAsteroid/eecb6be6ddc3406caaa5cdd2c4a9be8f/photo?Query=2024%20yr4&amp;amp;mediaType=photo&amp;amp;sortBy=&amp;amp;dateRange=Anytime&amp;amp;totalCount=9&amp;amp;currentItemNo=1"&gt;European Space Agency via AP&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;I was preparing for my early morning class back in January 2025 when I received &lt;a href="https://science.nasa.gov/blogs/planetary-defense/2025/01/29/nasa-shares-observations-of-recently-identified-near-earth-asteroid/"&gt;a notice regarding an asteroid called 2024 YR4&lt;/a&gt;. It said the probability it could hit Earth was unusually high. &lt;/p&gt;
297.  
298. <p>As defending Earth from unexpected intruders such as asteroids is <a href="https://scholar.google.com/citations?user=8_qb8h8AAAAJ&hl=en">part of my expertise</a>, I immediately started receiving questions from my students and colleagues about what was happening. </p>
299.  
300. <p>When scientists spot an asteroid whose trajectory might <a href="https://theconversation.com/neowise-the-nasa-mission-that-cataloged-objects-around-earth-for-over-a-decade-has-come-to-an-end-237921">take it close to Earth</a>, they monitor it frequently and calculate the probability that it might collide with our planet. As they receive more observational data, they get a better picture of what could happen. </p>
301.  
302. <p>Just having more data points early doesn’t make scientists’ predictions better. They need to keep following the asteroid as it moves through space to better understand its trajectory.</p>
303.  
304. <p>Reflecting on the incident a few months later, I wondered whether there might have been a better way for scientists to communicate about the risk with the public. We got accurate information, but as the questions I heard indicated, it wasn’t always enough to understand what it actually means. </p>
305.  
306. <h2>Numbers change every day</h2>
307.  
308. <p>The 2024 YR24 asteroid has a <a href="https://blogs.nasa.gov/webb/2025/04/02/nasas-webb-finds-asteroid-2024-yr4-is-building-sized/">diameter of about 196 feet (60 meters)</a> – equivalent to approximately a 15-story building in length.</p>
309.  
310. <p>At the time of the announcement in January, the asteroid’s impact probability was reported to <a href="https://science.nasa.gov/blogs/planetary-defense/2025/01/29/nasa-shares-observations-of-recently-identified-near-earth-asteroid/">exceed 1%</a>. The impact probability describes how likely a hazardous asteroid is to hit Earth. For example, if the impact probability is 1%, it means that in 1 of 100 cases, it hits Earth. One in 100 is kind of rare, but still too close for comfort if you’re talking about the odds of a collision that could devastate Earth.</p>
311.  
312. <p>Over time, though, further observations and analyses revealed an almost-zero chance of this asteroid colliding with Earth. </p>
313.  
314. <p>After the initial notice in January, the impact probability continuously increased up to 3.1% on <a href="https://science.nasa.gov/blogs/planetary-defense/2025/02/19/dark-skies-bring-new-observations-of-asteroid-2024-yr4-lower-impact-probability/">Feb. 18</a>, but dropped to 1.5% on <a href="https://science.nasa.gov/blogs/planetary-defense/2025/02/19/dark-skies-bring-new-observations-of-asteroid-2024-yr4-lower-impact-probability/">Feb. 19</a>. Then, the impact probability continuously went down, until it hit 0.004% on <a href="https://science.nasa.gov/blogs/planetary-defense/2025/02/24/latest-calculations-conclude-asteroid-2024-yr4-now-poses-no-significant-threat-to-earth-in-2032-and-beyond/">Feb. 24</a>. <a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20YR4">As of June 15</a>, it now has an impact probability of less than 0.0000081%.</p>
315.  
316. <figure class="align-center zoomable">
317.            <a href="https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the orbit paths of Earth, 2024 YR4 and some other planets in the solar system. 2024 YR4's orbit intersects with Earth's." src="https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668464/original/file-20250516-56-eggnpx.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
318.            <figcaption>
319.              <span class="caption">The orbit of 2024 YR4 will take it close to Earth, but scientists have found the chance of a collision to be exceedingly low.</span>
320.              <span class="attribution"><a class="source" href="https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%20YR4&view=VOP">NASA/JPL</a></span>
321.            </figcaption>
322.          </figure>
323.  
324. <p>But while the probability of hitting Earth went down, the probability of the asteroid hitting the Moon started increasing. It went up to 1.7% on <a href="https://science.nasa.gov/blogs/planetary-defense/2025/02/24/latest-calculations-conclude-asteroid-2024-yr4-now-poses-no-significant-threat-to-earth-in-2032-and-beyond/">Feb. 24</a>. As of April 2, it is <a href="https://science.nasa.gov/blogs/planetary-defense/2025/04/02/nasa-update-on-the-size-estimate-and-lunar-impact-probability-of-asteroid-2024-yr4/">3.8%</a>.</p>
325.  
326. <p>If it hits the Moon, some ejected materials from this collision could reach the Earth. However, these materials would burn away when they enter the Earth’s thick atmosphere. </p>
327.  
328. <h2>Impact probability</h2>
329.  
330. <p>To see whether an approaching object could hit Earth, researchers find out what an asteroid’s orbit looks like using a technique called astrometry. This technique can accurately determine an object’s orbit, down to only a few kilometers of uncertainty. But astrometry needs accurate observational data taken for a long time. </p>
331.  
332. <figure>
333.            <iframe width="440" height="260" src="https://www.youtube.com/embed/53Js-_vo3mo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
334.            <figcaption><span class="caption">If an asteroid might get close to Earth, astronomers take observational data to better track the object’s path and eliminate uncertainty.</span></figcaption>
335.          </figure>
336.  
337. <p>Any uncertainty in the calculation of the object’s orbit causes variations in the predicted solution. Instead of one precise orbit, the calculation usually gives scientists a cloud of its possible orbits. The ellipse enclosing these locations is called an error ellipse. </p>
338.  
339. <p>The <a href="https://doi.org/10.1016/j.icarus.2015.05.032">impact probability</a> describes how many orbital predictions in this ellipse hit the Earth. </p>
340.  
341. <p>Without enough observational data, the orbital uncertainty is high, so the ellipse tends to be large. In a large ellipse, there’s a higher chance that the ellipse “accidentally” includes Earth – even if the center is off the planet. So, even if an asteroid ultimately won’t hit Earth, its error ellipse might <a href="https://doi.org/10.1016/j.icarus.2015.05.032">still include the planet</a> before scientists collect enough data to narrow down the uncertainty. </p>
342.  
343. <p>As the level of uncertainty goes down, the ellipse shrinks. So, when Earth is inside a small error ellipse, the impact probability may become higher than when it’s inside a large error ellipse. Once the error ellipse shrinks enough that it no longer includes Earth, the impact probability goes down significantly. That’s what happened to 2024 YR4.</p>
344.  
345. <figure class="align-center zoomable">
346.            <a href="https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing impact probability on the y axis and time on the x axis, with three drawings of the Earth and an error ellipse. As time goes on, the ellipse shrinks and in the third drawing it isn't overlapping with the Earth." src="https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=310&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=310&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=310&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=390&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=390&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668495/original/file-20250516-62-591osa.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=390&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
347.            <figcaption>
348.              <span class="caption">As the error ellipse shrinks, the chance of the asteroid hitting Earth either goes down or goes way up, if it ends up overlapping with the Earth.</span>
349.              <span class="attribution"><span class="source">Toshi Hirabayashi</span></span>
350.            </figcaption>
351.          </figure>
352.  
353. <p>The impact probability is a single, practical value offering meaningful insight into an impact threat. However, just using the impact probability without any context may not provide meaningful guidelines to the public, as we saw with 2024 YR4. </p>
354.  
355. <p>Holding on and waiting for more data to refine a collision prediction, or introducing new metrics for assessing impacts on Earth, are alternative courses of action to provide people with better guidelines for future threats before adding confusion and fear.</p><img src="https://counter.theconversation.com/content/249834/count.gif" alt="The Conversation" width="1" height="1" />
356. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;I have been studying planetary defense, particularly being part of past, ongoing, and future small body missions. I was part of the NASA/DART mission. I am currently part of the NASA/Lucy mission and the ESA/Hera mission. I am also on the Hayabusa2# team, led by the Japanese Aerospace Exploration Agency (JAXA), as part of an international collaboration. I have no affiliation with JAXA.  &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
357.    <summary>Keeping Earth safe from asteroids isn’t just spotting them – it’s also helping people understand what a high-impact probability with Earth means.</summary>
358.    <author>
359.      <name>Toshi Hirabayashi, Associate Professor of Aerospace Engineering, Georgia Institute of Technology</name>
360.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/toshi-hirabayashi-1647682"/>
361.    </author>
362.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
363.  </entry>
364.  <entry>
365.    <id>tag:theconversation.com,2011:article/259233</id>
366.    <published>2025-06-24T12:35:37Z</published>
367.    <updated>2025-06-24T12:35:37Z</updated>
368.    <link rel="alternate" type="text/html" href="https://theconversation.com/the-vera-c-rubin-observatory-will-help-astronomers-investigate-dark-matter-continuing-the-legacy-of-its-pioneering-namesake-259233"/>
369.    <title>The Vera C. Rubin Observatory will help astronomers investigate dark matter, continuing the legacy of its pioneering namesake</title>
370.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/675460/original/file-20250619-62-xds3ac.jpg?ixlib=rb-4.1.0&amp;amp;rect=1438%2C0%2C6178%2C3472&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The Rubin Observatory is scheduled to release its first images in 2025.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://noirlab.edu/public/images/iotw2229a/"&gt;RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/B. Quint&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Everything in space – from the Earth and Sun to black holes – accounts for just &lt;a href="https://iopscience.iop.org/article/10.3847/1538-4357/ad3fb5"&gt;15% of all matter in the universe&lt;/a&gt;. The rest of the cosmos seems to be made of an invisible material astronomers call &lt;a href="https://theconversation.com/dark-matter-the-mystery-substance-physics-still-cant-identify-that-makes-up-the-majority-of-our-universe-85808"&gt;dark matter&lt;/a&gt;. &lt;/p&gt;
371.  
372. <p>Astronomers know dark matter exists because its gravity affects other things, such as light. But understanding what dark matter is remains an active area of research.</p>
373.  
374. <p>With the release of its <a href="https://rubinobservatory.org/news/rubin-first-look">first images</a> this month, the Vera C. Rubin Observatory has begun a 10-year mission to help unravel the mystery of dark matter. The observatory will continue the legacy of its namesake, a trailblazing astronomer who advanced our understanding of the other 85% of the universe.</p>
375.  
376. <p>As a <a href="https://airandspace.si.edu/people/staff/samantha-thompson">historian of astronomy</a>, I’ve studied how Vera Rubin’s contributions have shaped astrophysics. The observatory’s name is fitting, given that its data will soon provide scientists with a way to build on her work and shed more light on dark matter.</p>
377.  
378. <h2>Wide view of the universe</h2>
379.  
380. <p>From its vantage point in the Chilean Andes mountains, the Rubin Observatory will document everything visible in the southern sky. Every three nights, the observatory and its 3,200 megapixel camera will make a record of the sky. </p>
381.  
382. <p>This camera, about the size of a small car, is the <a href="https://rubinobservatory.org/explore/how-rubin-works/technology/camera">largest digital camera ever built</a>. Images will capture an area of the sky roughly 45 times the size of the full Moon. With a big camera with a wide field of view, Rubin will produce about five petabytes of data every year. That’s <a href="https://www.npr.org/2019/04/10/711723383/watch-earth-gets-its-first-look-at-a-black-hole">roughly 5,000 years’ worth of MP3 songs</a>.</p>
383.  
384. <p>After weeks, months and years of observations, astronomers will have a time-lapse record revealing anything that explodes, flashes or moves – <a href="https://www.space.com/6638-supernova.html">such as supernovas</a>, <a href="https://www.space.com/15396-variable-stars.html">variable stars</a> or asteroids. They’ll also have the largest survey of galaxies ever made. These galactic views are key to investigating dark matter.</p>
385.  
386. <h2>Galaxies are the key</h2>
387.  
388. <p>Deep field images from the <a href="https://esahubble.org/images/heic0611b/">Hubble Space Telescope</a>, the <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">James Webb Space Telescope</a> and others have visually revealed the abundance of galaxies in the universe. These images are taken with a long exposure time to collect the most light, so that even very faint objects show up.</p>
389.  
390. <p>Researchers now know that those galaxies aren’t randomly distributed. Gravity and dark matter pull and guide them into a structure that resembles a spider’s web or a tub of bubbles. The Rubin Observatory will expand upon these previous galactic surveys, increasing the precision of the data and capturing billions more galaxies. </p>
391.  
392. <p>In addition to helping structure galaxies throughout the universe, dark matter also distorts the appearance of galaxies through an effect referred to as <a href="https://esawebb.org/wordbank/gravitational-lensing/">gravitational lensing</a>. </p>
393.  
394. <p>Light travels through space in a straight line − unless it gets close to something massive. Gravity bends light’s path, which distorts the way we see it. This gravitational lensing effect provides clues that could help astronomers locate dark matter. The stronger the gravity, the bigger the bend in light’s path.</p>
395.  
396. <figure class="align-center zoomable">
397.            <a href="https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Many galaxies, represented as bright dots, some blurred, against a dark background." src="https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/675243/original/file-20250618-62-7m86qz.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
398.            <figcaption>
399.              <span class="caption">The white galaxies seen here are bound in a cluster. The gravity from the galaxies and the dark matter bends the light from the more distant galaxies, creating contorted and magnified images of them.</span>
400.              <span class="attribution"><a class="source" href="https://esawebb.org/images/weic2209a/">NASA, ESA, CSA and STScI</a></span>
401.            </figcaption>
402.          </figure>
403.  
404. <h2>Discovering dark matter</h2>
405.  
406. <p>For centuries, astronomers tracked and measured the motion of planets in the solar system. They found that all the planets followed the path predicted by <a href="https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/newtons-laws-of-motion/">Newton’s laws of motion</a>, except for Uranus. Astronomers and mathematicians reasoned that if Newton’s laws are true, there must be some missing matter – another massive object – out there tugging on Uranus. <a href="https://www.nasa.gov/history/175-years-ago-astronomers-discover-neptune-the-eighth-planet/">From this hypothesis</a>, they discovered Neptune, confirming Newton’s laws.</p>
407.  
408. <p>With the ability to see fainter objects in the 1930s, astronomers began tracking the motions of galaxies. </p>
409.  
410. <p>California Institute of Technology astronomer <a href="https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/fritz-zwicky">Fritz Zwicky</a> coined the term dark matter in 1933, after observing <a href="https://www.nasa.gov/image-article/coma-galaxy-cluster/">galaxies in the Coma Cluster</a>. He calculated the mass of the galaxies based on their speeds, which did not match their mass based on the number of stars he observed. </p>
411.  
412. <p>He suspected that the cluster could contain an invisible, missing matter that kept the galaxies from flying apart. But for several decades he lacked enough observational evidence to support his theory.</p>
413.  
414. <figure class="align-center zoomable">
415.            <a href="https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman adjusting a large piece of equipment." src="https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/675244/original/file-20250618-56-vwa3gg.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
416.            <figcaption>
417.              <span class="caption">Vera Rubin operates the Carnegie spectrograph at Kitt Peak National Observatory in Tucson.</span>
418.              <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/noirlab2003a/">Carnegie Institution for Science</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
419.            </figcaption>
420.          </figure>
421.  
422. <h2>Enter Vera Rubin</h2>
423.  
424. <p>In 1965, <a href="https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/vera-rubin-dark-matter">Vera Rubin</a> became the first women hired onto the scientific staff at the Carnegie Institution’s Department of Terrestrial Magnetism in Washington, D.C. </p>
425.  
426. <p>She worked with Kent Ford, who had built an extremely sensitive <a href="https://www.scientificamerican.com/article/ancient-stars-how-does-spectrograph-work/">spectrograph</a> and was looking to apply it to a scientific research project. Rubin and Ford used the spectrograph to measure how fast stars orbit around the center of their galaxies. </p>
427.  
428. <p>In the solar system, where most of the mass is within the Sun at the center, the closest planet, Mercury, moves faster than the farthest planet, Neptune.</p>
429.  
430. <p>“We had expected that as stars got farther and farther from the center of their galaxy, they would orbit slower and slower,” <a href="https://books.google.com/books?id=OVBUt6yrMtAC&">Rubin said in 1992</a>. </p>
431.  
432. <p>What they found in galaxies surprised them. Stars far from the galaxy’s center were moving <a href="https://doi.org/10.1086/150317">just as fast as stars closer in</a>. </p>
433.  
434. <p>“And that really leads to only two possibilities,” <a href="https://books.google.com/books?id=OVBUt6yrMtAC&">Rubin explained</a>. “Either Newton’s laws don’t hold, and physicists and astronomers are woefully afraid of that … (or) stars are responding to the gravitational field of matter which we don’t see.”</p>
435.  
436. <p>Data piled up as Rubin created plot after plot. Her colleagues didn’t doubt her observations, but the interpretation remained a debate. <a href="https://repository.aip.org/rubin-vera-1989-april-3">Many people were reluctant</a> to accept that dark matter was necessary to account for the findings in Rubin’s data. </p>
437.  
438. <p>Rubin continued studying galaxies, measuring how fast stars moved within them. She wasn’t interested in investigating dark matter itself, but she carried on with documenting its effects on the motion of galaxies.  </p>
439.  
440. <figure class="align-center zoomable">
441.            <a href="https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A quarter with a woman looking upwards engraved onto it." src="https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/675245/original/file-20250618-56-z4fjt6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
442.            <figcaption>
443.              <span class="caption">A U.S quarter honors Vera Rubin’s contributions to our understanding of dark matter.</span>
444.              <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/rubin-2025-americanwomen-quarterscoin-verarubin/">United States Mint</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
445.            </figcaption>
446.          </figure>
447.  
448. <h2>Vera Rubin’s legacy</h2>
449.  
450. <p>Today, more people are aware of Rubin’s observations and contributions to our understanding of dark matter. In 2019, a congressional bill was introduced to rename the former Large Synoptic Survey Telescope to the Vera C. Rubin Observatory. In June 2025, the U.S. Mint <a href="https://womenshistory.si.edu/blog/new-quarter-honors-vera-rubin-astronomer-who-revealed-universes-hidden-mass">released a quarter</a> featuring Vera Rubin.</p>
451.  
452. <p>Rubin continued to accumulate data about the motions of galaxies throughout her career. Others picked up where she left off and have helped <a href="https://doi.org/10.1038/s41550-017-0059">advance dark matter research</a> over the past 50 years.</p>
453.  
454. <p>In the 1970s, physicist James Peebles and astronomers Jeremiah Ostriker and Amos Yahil <a href="https://doi.org/10.1086/152513">created computer simulations of individual galaxies</a>. They concluded, similarly to Zwicky, that there was not enough visible matter in galaxies to keep them from flying apart. </p>
455.  
456. <p>They suggested that whatever dark matter is − be it cold stars, black holes or some unknown particle − there could be as much as 10 times the amount of dark matter than ordinary matter in galaxies.</p>
457.  
458. <p>Throughout its 10-year run, the Rubin Observatory should give even more researchers the opportunity to add to our understanding of dark matter.</p><img src="https://counter.theconversation.com/content/259233/count.gif" alt="The Conversation" width="1" height="1" />
459. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Samantha Thompson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
460.    <summary>Vera C. Rubin’s research into stars in galaxies led to the modern understanding of dark matter.</summary>
461.    <author>
462.      <name>Samantha Thompson, Astronomy Curator, National Air and Space Museum, Smithsonian Institution</name>
463.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/samantha-thompson-2415968"/>
464.    </author>
465.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
466.  </entry>
467.  <entry>
468.    <id>tag:theconversation.com,2011:article/258786</id>
469.    <published>2025-06-23T12:38:03Z</published>
470.    <updated>2025-06-23T12:38:03Z</updated>
471.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomy-has-a-major-data-problem-simulating-realistic-images-of-the-sky-can-help-train-algorithms-258786"/>
472.    <title>Astronomy has a major data problem – simulating realistic images of the sky can help train algorithms</title>
473.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/674229/original/file-20250613-56-qi55ha.png?ixlib=rb-4.1.0&amp;amp;rect=0%2C922%2C4004%2C2252&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;A simulation of a set of synthetic galaxies.  Photons are sampled from these galaxies and have been simulated through the Earth&amp;#39;s atmosphere, a telescope and a sensor using a code called PhoSim.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;John Peterson/Purdue&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Professional astronomers don’t make discoveries by looking through an eyepiece like you might with a backyard telescope. Instead, they collect digital images in &lt;a href="https://theconversation.com/new-powerful-telescopes-allow-direct-imaging-of-nascent-galaxies-12-billion-light-years-away-74910"&gt;massive cameras attached to large telescopes&lt;/a&gt;. &lt;/p&gt;
474.  
475. <p>Just as you might have an endless library of digital photos stored in your cellphone, many astronomers collect more photos than they would ever have the time to look at. Instead, <a href="https://www.physics.purdue.edu/people/faculty/peterson.php">astronomers like me</a> look at some of the images, then build algorithms and later use computers to combine and analyze the rest.</p>
476.  
477. <p>But how can we know that the algorithms we write will work, when we don’t even have time to look at all the images? We can practice on some of the images, but one new way to build the best algorithms is to simulate some fake images as accurately as possible.</p>
478.  
479. <p>With fake images, we can customize the exact properties of the objects in the image. That way, we can see if the algorithms we’re training can uncover those properties correctly. </p>
480.  
481. <p>My research group and collaborators have found that the best way to create fake but realistic astronomical images is to painstakingly simulate light and its interaction with everything it encounters. Light is composed of <a href="https://theconversation.com/do-photons-wear-out-an-astrophysicist-explains-lights-ability-to-travel-vast-cosmic-distances-without-losing-energy-252880">particles called photons</a>, and we can simulate each photon. We wrote a publicly available code to do this called the <a href="http://www.phosim.org">photon simulator, or PhoSim</a>.</p>
482.  
483. <p>The goal of the PhoSim project is to create realistic fake images that help us understand where distortions in images from real telescopes come from. The fake images help us train programs that sort through images from real telescopes. And the results from studies using PhoSim can also help astronomers correct distortions and defects in their real telescope images.</p>
484.  
485. <h2>The data deluge</h2>
486.  
487. <p>But first, why is there so much astronomy data in the first place? This is primarily due to the rise of dedicated survey telescopes. A survey telescope maps out a region on the sky rather than just pointing at specific objects.</p>
488.  
489. <p>These observatories all have a large collecting area, a large field of view and a dedicated survey mode to collect as much light over a period of time as possible. Major surveys from the past two decades include the <a href="https://www.sdss.org/">SDSS</a>, <a href="https://science.nasa.gov/mission/kepler/">Kepler</a>, <a href="https://noirlab.edu/public/programs/ctio/victor-blanco-4m-telescope/decam/">Blanco-DECam</a>, <a href="https://hsc.mtk.nao.ac.jp/ssp/">Subaru HSC</a>, <a href="https://science.nasa.gov/mission/tess/">TESS</a>, <a href="https://www.ztf.caltech.edu/">ZTF</a> and <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid">Euclid</a>.</p>
490.  
491. <p>The <a href="http://www.rubinobservatory.org">Vera Rubin Observatory</a> in Chile has recently finished construction and will soon join those. Its survey begins soon after its official “<a href="https://doi.org/10.1038/d41586-025-01798-2">first look” event on June 23, 2025</a>. It will have a particularly strong set of survey capabilities. </p>
492.  
493. <p>The Rubin observatory can look at a region of the sky all at once that is several times larger than the full Moon, and it can survey the entire southern celestial hemisphere every few nights. </p>
494.  
495. <figure class="align-center zoomable">
496.            <a href="https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An observatory, which looks like a building with a dome atop it, on a mountainside, with a starry sky shown in the background." src="https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/673780/original/file-20250611-56-rj3bnr.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
497.            <figcaption>
498.              <span class="caption">The Vera Rubin Observatory will take in lots of light to construct maps of the sky.</span>
499.              <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/iotw2207a">Rubin Observatory/NSF/AURA/B. Quint</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
500.            </figcaption>
501.          </figure>
502.  
503. <p>A survey can shed light on practically every topic in astronomy. </p>
504.  
505. <p>Some of the ambitious research questions include: making measurements about <a href="https://theconversation.com/we-need-to-consider-alternatives-to-dark-matter-that-better-explain-cosmological-observations-226765">dark matter</a> and <a href="https://theconversation.com/dark-energy-may-have-once-been-springier-than-it-is-today-desi-cosmologists-explain-what-their-collaborations-new-measurement-says-about-the-universes-history-253067">dark energy</a>, mapping the Milky Way’s distribution of stars, <a href="https://theconversation.com/neowise-the-nasa-mission-that-cataloged-objects-around-earth-for-over-a-decade-has-come-to-an-end-237921">finding asteroids</a> in the solar system, building a three-dimensional map of galaxies in the universe, finding new <a href="https://theconversation.com/goodbye-kepler-hello-tess-passing-the-baton-in-the-search-for-distant-planets-93688">planets outside the solar system</a> and tracking millions of objects that change over time, <a href="https://theconversation.com/im-an-astrophysicist-mapping-the-universe-with-data-from-the-chandra-x-ray-observatory-clear-sharp-photos-help-me-study-energetic-black-holes-229668">including supernovas</a>.</p>
506.  
507. <p>All of these surveys create a massive data deluge. They generate tens of terabytes every night – that’s millions to billions of pixels collected in seconds. In the <a href="https://rubinobservatory.org/explore/how-rubin-works/technology/data">extreme case of the Rubin observatory</a>, if you spent all day long looking at images equivalent to the size of a 4K television screen for about one second each, you’d be looking at them 25 times too slow and you’d never keep up. </p>
508.  
509. <p>At this rate, no individual human could ever look at all the images. But automated programs can process the data. </p>
510.  
511. <p>Astronomers don’t just survey an astronomical object like a planet, galaxy or supernova once, either. Often <a href="https://theconversation.com/astronomers-have-learned-lots-about-the-universe-but-how-do-they-study-astronomical-objects-too-distant-to-visit-214320">we measure</a> the same object’s size, shape, brightness and position in many different ways under many different conditions.</p>
512.  
513. <p>But more measurements do come with more complications. For example, measurements taken under certain weather conditions or on one part of the camera may disagree with others at different locations or under different conditions. Astronomers can correct these errors – called systematics – with careful calibration or algorithms, but only if we understand the reason for the inconsistency between different measurements. That’s where PhoSim comes in. Once corrected, we can use all the images and make more detailed measurements.</p>
514.  
515. <h2>Simulations: One photon at a time</h2>
516.  
517. <p>To understand the origin of these systematics, we built <a href="https://www.phosim.org">PhoSim</a>, which can simulate the propagation of light particles – photons – through the Earth’s atmosphere and then into the telescope and camera.</p>
518.  
519. <figure>
520.            <iframe width="440" height="260" src="https://www.youtube.com/embed/3pc8aPeeMBs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
521.            <figcaption><span class="caption">A simulation of photons traveling from a single star to the Vera Rubin Observatory, made using PhoSim. The layers of turbulence in the atmosphere move according to wind patterns (top middle), and the mirrors deform (top right) depending on the temperature and forces exerted on them. The photons with different wavelengths (colors) are sampled from a star, refract through the atmosphere and then interact with the telescope’s mirrors, filter and lenses. Finally, the photons eject electrons in the sensor (bottom middle) that are counted in pixels to make an image (bottom right). John Peterson/Purdue</span></figcaption>
522.          </figure>
523.  
524. <p>PhoSim simulates the atmosphere, including air turbulence, as well as distortions from the shape of the telescope’s mirrors and the electrical properties of the sensors. The photons are propagated using a variety of physics that predict what photons do when they encounter the air and the telescope’s mirrors and lenses. </p>
525.  
526. <p>The simulation ends by collecting electrons that have been <a href="https://en.wikipedia.org/wiki/Charge-coupled_device">ejected by photons</a> into a grid of pixels, to make an image.</p>
527.  
528. <p>Representing the light as trillions of photons is computationally efficient and an application of the <a href="https://en.wikipedia.org/wiki/Monte_Carlo_method">Monte Carlo method</a>, which uses random sampling. Researchers used PhoSim to verify some aspects of the Rubin observatory’s design and estimate how its images would look.</p>
529.  
530. <figure class="align-center ">
531.            <img alt="Rubin simulation with PhoSim, showing black dots representing stars and galaxies against a bright background" src="https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/674261/original/file-20250613-62-4kzf3u.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
532.            <figcaption>
533.              <span class="caption">A simulations of a series of exposures of stars, galaxies and background light through the Rubin observatory using PhoSim. Photons are sampled from the objects and then interact with the Earth’s atmosphere and Rubin’s telescope and camera.</span>
534.              <span class="attribution"><span class="source">John Peterson/Purdue</span></span>
535.            </figcaption>
536.          </figure>
537.  
538. <p>The results are complex, but so far we’ve connected the variation in temperature across telescope mirrors directly to astigmatism – angular blurring – in the images. We’ve also studied how high-altitude turbulence in the atmosphere that can disturb light on its way to the telescope shifts the positions of stars and galaxies in the image and causes blurring patterns that correlate with the wind. We’ve demonstrated how the electric fields in telescope sensors – which are intended to be vertical – can get distorted and warp the images. </p>
539.  
540. <p>Researchers can use these new results to correct their measurements and better take advantage of all the data that telescopes collect. </p>
541.  
542. <p>Traditionally, astronomical analyses haven’t worried about this level of detail, but the meticulous measurements with the current and future surveys will have to. Astronomers can make the most out of this deluge of data by using simulations to achieve a deeper level of understanding.</p><img src="https://counter.theconversation.com/content/258786/count.gif" alt="The Conversation" width="1" height="1" />
543. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;John Peterson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
544.    <summary>To make a truly realistic fake picture of a galaxy, you can model exactly how light particles travel through the atmosphere and telescope to reach its sensor.</summary>
545.    <author>
546.      <name>John Peterson, Assoc. Professor of Physics and Astronomy, Purdue University</name>
547.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/john-peterson-2407885"/>
548.    </author>
549.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
550.  </entry>
551.  <entry>
552.    <id>tag:theconversation.com,2011:article/256398</id>
553.    <published>2025-06-16T12:39:30Z</published>
554.    <updated>2025-06-16T12:39:30Z</updated>
555.    <link rel="alternate" type="text/html" href="https://theconversation.com/is-mars-really-red-a-physicist-explains-the-planets-reddish-hue-and-why-it-looks-different-to-some-telescopes-256398"/>
556.    <title>Is Mars really red? A physicist explains the planet’s reddish hue and why it looks different to some telescopes</title>
557.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/667706/original/file-20250513-56-vwwqg9.jpg?ixlib=rb-4.1.0&amp;amp;rect=71%2C0%2C937%2C527&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Siccar Point, photographed by the Curiosity rover, is near Mars&amp;#39; Gale Crater. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://apod.nasa.gov/apod/ap220831.html"&gt;NASA/JPL-Caltech/MSSS; Processing &amp;amp; License: Kevin M. Gill&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;
558.  
559. <p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>.</em></p>
560.  
561. <hr>
562.  
563. <blockquote>
564. <p><strong>Is Mars really as red as people say it is? – Jasmine, age 14, Everson, Washington</strong></p>
565. </blockquote>
566.  
567. <hr>
568.  
569. <p>People from cultures across the world have been looking at Mars since ancient times. Because it appears reddish, it has often been called the red planet. </p>
570.  
571. <p>The English name for the planet comes from the Romans, who named it after <a href="https://www.britannica.com/topic/Mars-Roman-god">their god of war</a> because its color reminded them of blood. In reality, the reddish color of Mars comes from <a href="https://science.nasa.gov/mars/facts/">iron oxide in the rocks and dust</a> covering its surface. </p>
572.  
573. <p>Your blood is also red <a href="https://theconversation.com/blood-in-your-veins-is-not-blue-heres-why-its-always-red-97064">because of a mixture of iron and oxygen</a> in a molecule called hemoglobin. So in a way, the ancient connection between the planet Mars and blood wasn’t completely wrong. Rust, which is a common form of iron oxide found here on Earth, also often has a reddish color. </p>
574.  
575. <figure class="align-center zoomable">
576.            <a href="https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Rust flakes on metal." src="https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668492/original/file-20250516-56-hk8xlj.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
577.            <figcaption>
578.              <span class="caption">Iron oxide, found in rust on old metal machinery, is the compound that colors rocks and dust on Mars’ surface reddish brown.</span>
579.              <span class="attribution"><a class="source" href="https://www.flickr.com/photos/7603557@N08/7383824180">Lars Hammar/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
580.            </figcaption>
581.          </figure>
582.  
583. <p><a href="https://facultyweb.kennesaw.edu/djoffe/">In my current research</a> on exoplanets, I observe different types of signals from planets beyond Earth. Lots of interesting physics goes into how researchers perceive the colors of planets and stars through different types of telescopes.</p>
584.  
585. <h2>Observing Mars with probes</h2>
586.  
587. <p>If you look closely at pictures of Mars taken by rovers on its surface, you can see that most of the planet isn’t purely red, but more of a rusty brown or tan color. </p>
588.  
589. <figure class="align-center zoomable">
590.            <a href="https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing the front of a lander as well as dusty, rocky terrain." src="https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=595&fit=crop&dpr=1 754w, https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=595&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/667141/original/file-20250511-56-f6zvnn.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=595&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
591.            <figcaption>
592.              <span class="caption">You can see Mars’ rusty color in this photo taken by the Viking lander.</span>
593.              <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA01522">NASA/JPL</a></span>
594.            </figcaption>
595.          </figure>
596.  
597. <p>Probes sent from Earth have taken pictures showing rocks with a rusty color. A 1976 <a href="https://photojournal.jpl.nasa.gov/catalog/PIA01522">picture from the Viking lander</a>, the very first spacecraft to land on Mars, shows the Martian ground covered with a layer of rusty orange dust. </p>
598.  
599. <p>Not all of Mars’ surface has the same color. At the poles, its ice caps appear white. These ice caps contain frozen water, like the ice we usually find on Earth, but these ice caps are also covered by a layer of <a href="https://science.nasa.gov/resource/dry-ice-on-mars/">frozen carbon dioxide</a> – dry ice. </p>
600.  
601. <p>This layer of dry ice can evaporate very quickly when sunlight shines on it and grows back again when it becomes dark. This process causes the white ice caps to grow and shrink in size depending on the Martian seasons.</p>
602.  
603. <figure class="align-center zoomable">
604.            <a href="https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of Mars from space. It looks reddish brown in color, with white clouds at the poles." src="https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/667707/original/file-20250513-56-ox4ihy.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
605.            <figcaption>
606.              <span class="caption">This picture from the Hubble Space Telescope shows the planet with the same rusty color covering large parts of its surface.</span>
607.              <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2018/10/4115-Image">NASA, ESA, Zolt G. Levay (STScI)</a></span>
608.            </figcaption>
609.          </figure>
610.  
611. <h2>Beyond visible light</h2>
612.  
613. <p>Mars also gives off light in colors that you can’t see with your eyes but that scientists can measure with special cameras on telescopes. </p>
614.  
615. <p>Light itself can be thought of not only as a wave but also as a <a href="https://www.symmetrymagazine.org/article/what-is-a-photon?language_content_entity=und">stream of particles called photons</a>. The amount of energy carried by each photon is related to its color. For example, blue and violet photons have more energy than orange and red photons. </p>
616.  
617. <figure class="align-center zoomable">
618.            <a href="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of the electromagnetic spectrum, with radio, micro and infrared waves having a longer wavelength than visible light, while UV, X-ray and gamma rays have shorter wavelengths than visible light." src="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=356&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=356&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=356&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=447&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=447&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668491/original/file-20250516-62-i9y8b9.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=447&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
619.            <figcaption>
620.              <span class="caption">The rainbow of visible light that you can see is only a small slice of all the kinds of light. Some telescopes can detect light with a longer wavelength, such as infrared light, or light with a shorter wavelength, such as ultraviolet light. Others can detect X-rays or radio waves.</span>
621.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Electromagnetic_spectrum#/media/File:EM_Spectrum_Properties_edit.svg">Inductiveload, NASA/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
622.            </figcaption>
623.          </figure>
624.  
625. <p><a href="https://science.nasa.gov/ems/10_ultravioletwaves/">Ultraviolet photons</a> have even more energy than the photons you can see with your eyes. These photons are found in direct sunlight, and because they have so much energy, they can damage the cells in your body. You <a href="https://theconversation.com/how-do-the-chemicals-in-sunscreen-protect-our-skin-from-damage-74355">can use sunscreen</a> to protect yourself from them. </p>
626.  
627. <p><a href="https://science.nasa.gov/ems/07_infraredwaves/">Infrared photons</a> have less energy than the photons you can see with your eyes, and you don’t need any special protection from them. This is how some types of night-vision goggles work: They can see light in the infrared spectrum as well as the visible color spectrum. Scientists can take pictures of Mars in the infrared spectrum using special cameras that work almost like night-vision goggles for telescopes. </p>
628.  
629. <figure class="align-center zoomable">
630.            <a href="https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two photos of Mars from space -- one labeled 'visible true color' that looks reddish brown and one labeled 'infrared false color' that looks green and red." src="https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/667709/original/file-20250513-68-7f07ph.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
631.            <figcaption>
632.              <span class="caption">The Hubble Space Telescope could take pictures in both visible light and infrared light.</span>
633.              <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/4179-Image">NASA, James Bell (Cornell University), Justin Maki (NASA-JPL), Mike J. Wolff (SSI)</a></span>
634.            </figcaption>
635.          </figure>
636.  
637. <p>The colors on the infrared picture aren’t really what the infrared light looks like, because you can’t see those colors with your eyes. They are called “false colors,” and researchers add them to look at the picture more easily. </p>
638.  
639. <p>When you compare the visible color picture and the infrared picture, you can see some of the same features – and the ice caps are visible in both sets of colors. </p>
640.  
641. <figure class="align-right zoomable">
642.            <a href="https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Mars shown from space, colored gray, green and brown." src="https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/667710/original/file-20250513-56-l20b51.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
643.            <figcaption>
644.              <span class="caption">A UV view of Mars with the MAVEN spacecraft.</span>
645.              <span class="attribution"><a class="source" href="https://science.nasa.gov/resource/maven-spacecraft-stuns-with-ultraviolet-views-of-red-planet/">NASA/LASP/CU Boulder</a></span>
646.            </figcaption>
647.          </figure>
648.  
649. <p>NASA’s MAVEN spacecraft, launched in 2013, has even taken <a href="https://science.nasa.gov/resource/maven-spacecraft-stuns-with-ultraviolet-views-of-red-planet/">pictures with ultraviolet light</a>, giving scientists a different view of both the surface of Mars and its atmosphere. </p>
650.  
651. <p>Each new type of picture tells scientists more about the Martian landscape. They hope to use these details to answer questions about how Mars formed, how long it had <a href="https://marsed.asu.edu/mep/volcanoes">active volcanoes</a>, where <a href="https://theconversation.com/ancient-mars-may-have-had-a-carbon-cycle-a-new-study-suggests-the-red-planet-may-have-once-been-warmer-wetter-and-more-favorable-for-life-255207">its atmosphere came from</a> and whether it had <a href="https://theconversation.com/our-mostly-dry-planetary-neighbors-once-had-lots-of-water-what-does-that-imply-for-us-43817">liquid water on its surface</a>. </p>
652.  
653. <p>Astronomers are always looking for new ways to take telescope pictures outside of the <a href="https://theconversation.com/where-does-black-fall-on-the-color-spectrum-a-color-scientist-explains-234540">regular visible spectrum</a>. They can even make images using <a href="https://theconversation.com/less-than-1-of-the-worlds-biggest-radio-telescope-is-complete-but-its-first-image-reveals-a-sky-dotted-with-ancient-galaxies-252382">radio waves</a>, microwaves, <a href="https://theconversation.com/im-an-astrophysicist-mapping-the-universe-with-data-from-the-chandra-x-ray-observatory-clear-sharp-photos-help-me-study-energetic-black-holes-229668">X-rays</a> and gamma rays. Each part of the spectrum they can use to look at an object in space represents new information they can learn from. </p>
654.  
655. <p>Even though people have been looking at Mars since ancient times, we still have much to learn about this fascinating neighbor.</p>
656.  
657. <hr>
658.  
659. <p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
660.  
661. <p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/256398/count.gif" alt="The Conversation" width="1" height="1" />
662. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;David Joffe receives funding from the NASA Office of STEM Engagement through a grant from the Georgia Space Grant Consortium&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
663.    <summary>Mars isn’t a bright, fire-engine red, but the iron oxide in its rocks makes it appear redder than other planets, especially from afar.</summary>
664.    <author>
665.      <name>David Joffe, Associate Professor of Physics, Kennesaw State University</name>
666.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/david-joffe-2390964"/>
667.    </author>
668.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
669.  </entry>
670.  <entry>
671.    <id>tag:theconversation.com,2011:article/252695</id>
672.    <published>2025-06-10T12:21:15Z</published>
673.    <updated>2025-06-10T12:21:15Z</updated>
674.    <link rel="alternate" type="text/html" href="https://theconversation.com/where-is-the-center-of-the-universe-252695"/>
675.    <title>Where is the center of the universe?</title>
676.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/665893/original/file-20250505-56-1mt7ki.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C64%2C1700%2C956&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;In space, there are four dimensions: length, width, height and time.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.gettyimages.com/detail/photo/milky-way-in-universe-abstract-night-sky-and-space-royalty-free-image/1200406584?phrase=the%2Buniverse"&gt;scaliger/iStock/NASA via Getty Images Plus&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;About a century ago, scientists were struggling to reconcile what seemed a contradiction in &lt;a href="https://www.space.com/17661-theory-general-relativity.html"&gt;Albert Einstein’s theory of general relativity&lt;/a&gt;. &lt;/p&gt;
677.  
678. <p><a href="https://asd.gsfc.nasa.gov/blueshift/index.php/2015/11/25/100-years-of-general-relativity/">Published in 1915</a>, and already widely accepted worldwide by physicists and mathematicians, the theory assumed the universe was static – unchanging, unmoving and immutable. In short, Einstein believed the size and shape of the universe today was, more or less, the same size and shape it had always been.</p>
679.  
680. <p>But when astronomers looked into the night sky at faraway galaxies with powerful telescopes, they saw hints the universe was anything but that. These new observations suggested the opposite – that it was, <a href="https://skyserver.sdss.org/dr1/en/astro/universe/universe.asp">instead, expanding</a>. </p>
681.  
682. <p>Scientists soon realized Einstein’s theory didn’t actually say the universe had to be static; the theory could support an expanding universe as well. Indeed, by using the same mathematical tools provided by Einstein’s theory, scientists created new models that showed the universe was, in fact, <a href="https://www.pbs.org/wgbh/aso/databank/entries/dp29hu.html">dynamic and evolving</a>. </p>
683.  
684. <p>I’ve spent decades trying to understand general relativity, including in my current job <a href="https://scholar.google.com/citations?user=GEn0OTgAAAAJ&hl=en">as a physics professor</a> teaching courses <a href="https://web.uri.edu/physics/meet/robert-coyne/">on the subject</a>. I know wrapping your head around the idea of an ever-expanding universe can feel daunting – and part of the challenge is overriding your natural intuition about how things work. For instance, it’s hard to imagine something as big as the universe not having a center at all, but physics says that’s the reality.</p>
685.  
686. <figure>
687.            <iframe width="440" height="260" src="https://www.youtube.com/embed/BBKV2N550XE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
688.            <figcaption><span class="caption">The universe gets bigger every day.</span></figcaption>
689.          </figure>
690.  
691. <h2>The space between galaxies</h2>
692.  
693. <p>First, let’s define what’s meant by “expansion.” On Earth, “expanding” means something is getting bigger. And in regard to the universe, that’s true, sort of. Expansion might also mean “everything is getting farther from us,” which is also true with regard to the universe. Point a telescope at distant galaxies and they all do appear <a href="https://science.nasa.gov/mission/hubble/science/science-highlights/discovering-a-runaway-universe/">to be moving away from us</a>. </p>
694.  
695. <p>What’s more, the farther away they are, the faster they appear to be moving. Those galaxies also seem to be moving away from each other. So it’s more accurate to say that everything in the universe is getting <a href="https://science.nasa.gov/dark-energy/#:%7E">farther away from everything else</a>, all at once.</p>
696.  
697. <p>This idea is subtle but critical. It’s easy to think about the creation of the universe like exploding fireworks: Start with <a href="https://physics.mit.edu/news/it-all-started-with-a-big-bang-the-quest-to-unravel-the-mystery-behind-the-birth-of-the-universe/">a big bang</a>, and then all the galaxies in the universe fly out in all directions from some central point. </p>
698.  
699. <p>But that analogy isn’t correct. Not only does it falsely imply that the expansion of the universe started from a single spot, which it didn’t, but it also suggests that the galaxies are the things that are moving, which isn’t entirely accurate. </p>
700.  
701. <p>It’s not so much the galaxies that are moving away from each other – it’s the space between galaxies, the fabric of the universe itself, that’s <a href="https://www.livescience.com/65978-what-happens-in-intergalactic-space.html">ever-expanding as time goes on</a>. In other words, it’s not really the galaxies themselves that are moving through the universe; it’s more that <a href="https://www.space.com/52-the-expanding-universe-from-the-big-bang-to-today.html">the universe itself</a> is carrying them farther away as it expands. </p>
702.  
703. <p>A common analogy is to imagine sticking some dots on the surface of a balloon. As you blow air into the balloon, it expands. Because the dots are stuck on the surface of the balloon, they get farther apart. Though they may appear to move, the dots actually stay exactly where you put them, and the distance between them gets bigger simply by virtue of the balloon’s expansion. </p>
704.  
705. <figure class="align-center zoomable">
706.            <a href="https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="split screen of a green balloon with red dots and a squiggle on the surface, lightly inflated and then much more blown up" src="https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/672328/original/file-20250604-74-2xt71o.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
707.            <figcaption>
708.              <span class="caption">It’s the space between the dots that’s growing.</span>
709.              <span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/edu/resources/lesson-plan/model-the-expanding-universe/">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
710.            </figcaption>
711.          </figure>
712.  
713. <p>Now think of the dots as galaxies and the balloon as the fabric of the universe, and you begin to get the picture. </p>
714.  
715. <p>Unfortunately, while this analogy is a good start, it doesn’t get the details quite right either.</p>
716.  
717. <h2>The 4th dimension</h2>
718.  
719. <p>Important to any analogy is an understanding of its limitations. Some flaws are obvious: A balloon is small enough to fit in your hand – not so the universe. Another flaw is more subtle. The balloon has two parts: its latex surface and its air-filled interior. </p>
720.  
721. <p>These two parts of the balloon are described differently in the language of mathematics. The balloon’s surface is two-dimensional. If you were walking around on it, you could move forward, backward, left, or right, but you couldn’t move up or down without leaving the surface. </p>
722.  
723. <p>Now it might sound like we’re naming four directions here – forward, backward, left and right – but those are just movements along two basic paths: side to side and front to back. That’s what makes the surface two-dimensional – length and width. </p>
724.  
725. <p>The inside of the balloon, on the other hand, is three-dimensional, so you’d be able to move freely in any direction, including up or down – length, width and height. </p>
726.  
727. <p>This is where the confusion lies. The thing we think of as the “center” of the balloon is a point somewhere in its interior, in the air-filled space beneath the surface. </p>
728.  
729. <p>But in this analogy, the universe is more like the latex surface of the balloon. The balloon’s air-filled interior has no counterpart in our universe, so we can’t use that part of the analogy – only the surface matters.</p>
730.  
731. <figure class="align-right zoomable">
732.            <a href="https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A blown-up purple balloon on a blue background." src="https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/671018/original/file-20250529-62-c5loiz.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
733.            <figcaption>
734.              <span class="caption">Trying to figure out how the universe works? Start by contemplating a balloon.</span>
735.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/single-pink-balloon-on-blue-background-royalty-free-image/671323546">Kristopher_K/iStock via Getty Images Plus</a></span>
736.            </figcaption>
737.          </figure>
738.  
739. <p>So asking, “Where’s the center of the universe?” is somewhat like asking, “Where’s the center of the balloon’s surface?” There simply isn’t one. You could travel along the surface of the balloon in any direction, for as long as you like, and you’d never once reach a place you could call its center because you’d never actually leave the surface.</p>
740.  
741. <p>In the same way, you could travel in any direction in the universe and would never find its center because, much like the surface of the balloon, it <a href="https://www.astronomy.com/science/ask-astro-where-is-the-center-of-the-universe/">simply doesn’t have one</a>.</p>
742.  
743. <p>Part of the reason this can be so challenging to comprehend is because of the way the universe is described in the language of mathematics. The surface of the balloon has two dimensions, and the balloon’s interior has three, but the universe exists in four dimensions. Because it’s not just about how things move in space, but how they move in time.</p>
744.  
745. <p>Our brains are wired to think about space and time separately. But in the universe, they’re interwoven into a single fabric, called “<a href="https://phys.org/news/2023-11-four-dimensional-universe.html">space-time</a>.” That unification changes the way the universe works relative to what our intuition expects.</p>
746.  
747. <p>And this explanation doesn’t even begin to answer the question of how something <a href="https://theconversation.com/what-is-the-universe-expanding-into-if-its-already-infinite-239702">can be expanding indefinitely</a> – scientists are still trying to puzzle out what powers this expansion.</p>
748.  
749. <p>So in asking about the center of the universe, we’re confronting the limits of our intuition. The answer we find – everything, expanding everywhere, all at once – is a glimpse of just how strange and beautiful our universe is.</p><img src="https://counter.theconversation.com/content/252695/count.gif" alt="The Conversation" width="1" height="1" />
750. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Rob Coyne receives funding from the National Aeronautics and Space Administration (NASA) and the US National Science Foundation (NSF).&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
751.    <summary>As the universe expands, it feels like it must be spreading out from some initial point. But a physicist explains why that’s not how it works. Hint: space-time is involved.</summary>
752.    <author>
753.      <name>Rob Coyne, Teaching Professor of Physics, University of Rhode Island</name>
754.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/rob-coyne-2350542"/>
755.    </author>
756.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
757.  </entry>
758.  <entry>
759.    <id>tag:theconversation.com,2011:article/258231</id>
760.    <published>2025-06-05T12:55:07Z</published>
761.    <updated>2025-06-05T12:55:07Z</updated>
762.    <link rel="alternate" type="text/html" href="https://theconversation.com/a-new-observatory-is-assembling-the-most-complete-time-lapse-record-of-the-night-sky-ever-258231"/>
763.    <title>A new observatory is assembling the most complete time-lapse record of the night sky ever</title>
764.    <content type="html">&lt;p&gt;On 23 June 2025, the world will get a look at the &lt;a href="https://rubinobservatory.org/news/rubin-first-look"&gt;first images&lt;/a&gt; from one of the most powerful telescopes ever built: the Vera C. Rubin Observatory. &lt;/p&gt;
765.  
766. <p>Perched high in the Chilean Andes, the observatory will take hundreds of images of the southern hemisphere sky, every night for 10 years. In doing so, it will create the most complete time-lapse record of our Universe ever assembled. This scientific effort is known as the <a href="https://www.lsst.org/about">Legacy Survey of Space and Time (LSST)</a>.</p>
767.  
768. <p>Rather than focusing on small patches of sky, the Rubin Observatory will scan the entire visible southern sky every few nights. Scientists will use this rolling deep-sky snapshot to track supernovae (exploding stars), asteroids, black holes, and galaxies as they evolve and change in real time. This is astronomy not as a static snapshot, but as a cosmic story unfolding night by night.</p>
769.  
770. <p>At the heart of the observatory lies a remarkable piece of engineering: a <a href="https://rubinobservatory.org/explore/how-rubin-works/technology/camera">digital camera</a> the size of a small car and weighing over three tonnes. With a staggering 3,200 megapixels, each image it captures has enough detail to spot a golf ball from 25km away.</p>
771.  
772. <hr>
773.  
774.  
775.  
776. <p><em><strong>Get your news from actual experts, straight to your inbox.</strong> <a href="https://theconversation.com/uk/newsletters?promoted=the-daily-2">Sign up to our daily newsletter</a> to receive all The Conversation UK’s latest coverage of news and research, from politics and business to the arts and sciences.</em></p>
777.  
778. <hr>
779.  
780. <p>Each image is so detailed that it would take hundreds of ultra-high-definition TV screens to display it in full. To capture the universe in colour, the camera uses enormous filters — each about the size of a dustbin lid — that allow through different types of light, from ultraviolet to near-infrared. </p>
781.  
782. <p>The observatory was first proposed in 2001, and construction at the Cerro Pachón ridge site in northern Chile began in April 2015. The first observations with a low-resolution test camera <a href="https://rubinobservatory.org/news/test-camera-sees-sky">were carried out</a> in October 2024, setting up the first images using the main camera, to be unveiled in June.</p>
783.  
784.  
785.  
786. <h2>Big questions</h2>
787.  
788. <p>The observatory is designed to tackle some of astronomy’s biggest questions. For instance, by measuring how galaxies cluster and move, the Rubin Observatory will help scientists investigate the nature of dark energy, the mysterious force driving the accelerating expansion of the Universe. </p>
789.  
790. <p>As a primary goal, it will map the large-scale structure of the Universe and investigate <a href="https://science.nasa.gov/universe/overview/building-blocks/#dark-matter">dark matter</a>, the invisible form of matter that makes up 27% of the cosmos. Dark matter acts as the “scaffolding” of the universe, a web-like structure that provides a framework for the formation of galaxies. </p>
791.  
792. <p>The observatory is named after the US astronomer <a href="https://www.britannica.com/biography/Vera-Rubin">Dr Vera Rubin</a>, whose groundbreaking work uncovered the first strong evidence for dark matter – the very phenomenon this telescope will explore in unprecedented detail. </p>
793.  
794. <p>As a woman in a male-dominated field, Rubin overcame numerous obstacles and remained a tireless advocate for equality in science. She died in 2016 at the age of 88, and her name on this observatory is a tribute not only to her science, but to her perseverance and her legacy of inclusion.</p>
795.  
796. <p>Closer to home, Rubin will help find and track <a href="https://rubinobservatory.org/slideshows/eyes-on-asteroids">millions of asteroids</a> and other objects that come near Earth – helping warn astronomers of any potential collisions. The observatory will also monitor stars that change in brightness, which can reveal planets orbiting them. </p>
797.  
798. <p>And it will capture rare and fleeting cosmic events, such as the collision of very dense objects called neutron stars, which release sudden bursts of light and ripples in space known as gravitational waves.</p>
799.  
800. <p>What makes this observatory particularly exciting is not just what we expect it to find, but what we can’t yet imagine. Many astronomical breakthroughs have come from chance: strange flashes in the night sky and puzzling movements of objects. Rubin’s massive, continuous data stream could reveal entirely new classes of objects or unknown physical processes.</p>
801.  
802. <figure class="align-center ">
803.            <img alt="LSST digital camera" src="https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/672454/original/file-20250605-56-nbjre9.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
804.            <figcaption>
805.              <span class="caption">The observatory is equipped with the world’s largest digital camera.</span>
806.              <span class="attribution"><a class="source" href="https://rubinobservatory.org/gallery/collections/main-gallery/dpkp1ku1qt0it5eu9aeuibf70r">RubinObs/NOIRLab/SLAC/DOE/NSF/AURA</a></span>
807.            </figcaption>
808.          </figure>
809.  
810. <p>But capturing this “movie of the universe” depends on something we often take for granted: dark skies. One of the growing challenges facing astronomers is <a href="https://www.space.com/megaconstellations-disruption-astronomy-like-light-pollution">light pollution</a> from satellite mega-constellations – a group of many satellites working together. </p>
811.  
812. <p>These satellites reflect sunlight and can leave bright streaks across telescope images, potentially interfering with the very discoveries Rubin is designed to make. While software can detect and remove some of these trails, doing so adds complexity, cost and can degrade the data.</p>
813.  
814. <p>Fortunately, solutions are already being explored. Rubin Observatory staff <a href="https://iopscience.iop.org/article/10.3847/1538-3881/abba3e/pdf">are developing simulation tools</a> to predict and reduce satellite interference. They are also working with satellite operators to dim or reposition spacecraft. These efforts are essential – not just for Rubin, but for the future of space science more broadly.</p>
815.  
816. <p>Rubin is a collaboration between the US National Science Foundation and the Department of Energy, with global partners contributing to data processing and scientific analysis. Importantly, much of the data will be publicly available, offering researchers, students and citizen scientists around the world the chance to make discoveries of their own.</p>
817.  
818. <p>The “first-look” event, which will unveil the first images from the observatory, will be livestreamed in English and Spanish, and celebrations are planned at venues around the world.</p>
819.  
820. <p>For astronomers, this is a once-in-a-generation moment – a project that will transform our view of the universe, spark public imagination and generate scientific insights for decades to come.</p><img src="https://counter.theconversation.com/content/258231/count.gif" alt="The Conversation" width="1" height="1" />
821. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Noelia Noël does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
822.    <summary>The Vera C. Rubin Observatory will capture enough detail to see a golf ball from 25km away.</summary>
823.    <author>
824.      <name>Noelia Noël, Senior Lecturer, School of Mathematics and Physics, University of Surrey</name>
825.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/noelia-noel-2408204"/>
826.    </author>
827.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
828.  </entry>
829.  <entry>
830.    <id>tag:theconversation.com,2011:article/257825</id>
831.    <published>2025-06-02T20:26:17Z</published>
832.    <updated>2025-06-02T20:26:17Z</updated>
833.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomers-thought-the-milky-way-was-doomed-to-crash-into-andromeda-now-theyre-not-so-sure-257825"/>
834.    <title>Astronomers thought the Milky Way was doomed to crash into Andromeda. Now they’re not so sure</title>
835.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/671460/original/file-20250602-56-o8xc4n.jpeg?ixlib=rb-4.1.0&amp;amp;rect=0%2C194%2C7510%2C4224&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://commons.wikimedia.org/wiki/File:M31-Andromede-16-09-2023-Hamois.jpg"&gt;Luc Viatour / Wikimedia&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;For years, astronomers have predicted a dramatic fate for our galaxy: a head-on collision with Andromeda, our nearest large galactic neighbour. This merger – expected in about 5 billion years – has become a staple of astronomy documentaries, textbooks and popular science writing.&lt;/p&gt;
836.  
837. <p>But in <a href="https://www.nature.com/articles/s41550-025-02563-1">our new study</a> published in Nature Astronomy, led by Till Sawala from the University of Helsinki, we find the Milky Way’s future might not be as certain previously assumed. </p>
838.  
839. <p>By carefully accounting for uncertainties in existing measurements, and including the gravitational influence of other nearby galaxies, we found there is only about a 50% chance the Milky Way and Andromeda will merge in the next 10 billion years. </p>
840.  
841. <h2>Why did we think a collision was inevitable?</h2>
842.  
843. <p>The idea that the Milky Way and Andromeda are on a collision course <a href="https://ui.adsabs.harvard.edu/abs/1917AJ.....30..175B/abstract">goes back more than a century</a>. Astronomers discovered Andromeda is moving toward us by measuring its radial velocity – its motion along our line of sight – using a slight change in the colour of its light called the Doppler shift. </p>
844.  
845. <p>But galaxies also drift sideways across the sky, a movement known as proper motion or transverse velocity. This sideways motion is incredibly difficult to detect, especially for galaxies millions of light years away. </p>
846.  
847. <p><a href="https://iopscience.iop.org/article/10.1088/0004-637X/753/1/8">Earlier studies</a> often assumed Andromeda’s transverse motion was small, making a future head-on collision seem almost certain.</p>
848.  
849. <h2>What’s different in this study?</h2>
850.  
851. <p>Our study did not have any new data. Instead, we took a fresh look at existing observations from the Hubble Space Telescope and the <a href="https://theconversation.com/the-best-space-telescope-you-never-heard-of-just-shut-down-253343">Gaia mission</a>.</p>
852.  
853. <p>Unlike earlier studies, our work incorporates the uncertainty in these measurements, rather than assuming their most likely values. </p>
854.  
855. <p>We simulated thousands of possible trajectories for the Milky Way and Andromeda trajectories, slightly varying the assumed initial conditions – things such as the speed and position of the two galaxies – each time. </p>
856.  
857. <p>When we started from the same assumptions the earlier studies made, we recovered the same results. However, we were also able to explore a larger range or possibilities. </p>
858.  
859. <p>We also included two additional galaxies that influence the future paths of the Milky Way and Andromeda: the Large Magellanic Cloud, a massive satellite galaxy currently falling into the Milky Way, and M33, also known as the Triangulum Galaxy, which orbits Andromeda. </p>
860.  
861. <figure class="align-center zoomable">
862.            <a href="https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A detailed photo of a white-and-pink pinwheel-shaped galaxy." src="https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=503&fit=crop&dpr=1 600w, https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=503&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=503&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=632&fit=crop&dpr=1 754w, https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=632&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/671449/original/file-20250602-68-b5b72l.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=632&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
863.            <figcaption>
864.              <span class="caption">The new study took into account the gravitational effect of the Triangulum Galaxy, which orbits Andromeda.</span>
865.              <span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1424a/">ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
866.            </figcaption>
867.          </figure>
868.  
869. <p>These companion galaxies exert gravitational tugs that change the motions of their hosts. </p>
870.  
871. <p>M33 nudges Andromeda slightly toward the Milky Way, increasing the chance of a merger. Meanwhile, the Large Magellanic Cloud shifts the Milky Way’s motion away from Andromeda, reducing the likelihood of a collision. </p>
872.  
873. <p>Taking all of this into account, we found that in about half of the simulated scenarios, the Milky Way and Andromeda do not merge at all within the next 10 billion years. </p>
874.  
875. <h2>What happens if they do – or don’t – collide?</h2>
876.  
877. <p>Even if a merger does happen, it’s unlikely to be catastrophic for Earth. Stars in galaxies are separated by enormous distances, so direct collisions are rare.</p>
878.  
879. <p>But over time, the galaxies would coalesce under gravity, forming a single, larger galaxy – probably an elliptical one, rather than the spirals we see today. </p>
880.  
881. <p>If the galaxies don’t merge, they may settle into a long, slow orbit around each other – close companions that never quite collide. It’s a gentler outcome, but it still reshapes our understanding of the Milky Way’s distant future.</p>
882.  
883. <figure class="align-center zoomable">
884.            <a href="https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three images of pairs of galaxies in increasingly close proximity." src="https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=669&fit=crop&dpr=1 600w, https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=669&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=669&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=840&fit=crop&dpr=1 754w, https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=840&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/671462/original/file-20250602-56-5kzg4s.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=840&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
885.            <figcaption>
886.              <span class="caption">Other galaxies show examples of three future scenarios for the Milky Way and Andromeda: galaxies passing in the night, a close encounter, a full collision and merger.</span>
887.              <span class="attribution"><span class="source">NASA / ESA</span></span>
888.            </figcaption>
889.          </figure>
890.  
891. <h2>What comes next?</h2>
892.  
893. <p>The biggest remaining uncertainty is the transverse velocity of Andromeda. Even small changes in this sideways motion can make the difference between a merger and a near miss. Future measurements will help refine this value and bring us closer to a clearer answer. </p>
894.  
895. <p>We don’t yet have a definitive answer about our own galaxy’s future. But exploring these possibilities shows just how much we’re still learning about the universe – even close to home.</p><img src="https://counter.theconversation.com/content/257825/count.gif" alt="The Conversation" width="1" height="1" />
896. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Ruby Wright receives funding from the Forrest Research Foundation. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Alexander Rawlings receives funding from the University of Helsinki Research Foundation and the European Research Council.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
897.    <summary>The odds of a galactic collision in our distant future are much lower than we thought, according to new simulations.</summary>
898.    <author>
899.      <name>Ruby Wright, Forrest Fellow in Astrophysics, The University of Western Australia</name>
900.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/ruby-wright-2224346"/>
901.    </author>
902.    <author>
903.      <name>Alexander Rawlings, Computational Astrophysicist, University of Helsinki</name>
904.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/alexander-rawlings-2404336"/>
905.    </author>
906.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
907.  </entry>
908.  <entry>
909.    <id>tag:theconversation.com,2011:article/256427</id>
910.    <published>2025-06-02T12:45:21Z</published>
911.    <updated>2025-06-02T12:45:21Z</updated>
912.    <link rel="alternate" type="text/html" href="https://theconversation.com/new-model-helps-to-figure-out-which-distant-planets-may-host-life-256427"/>
913.    <title>New model helps to figure out which distant planets may host life</title>
914.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/670826/original/file-20250528-56-4pr82o.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C2300%2C1293&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Some &amp;#39;water worlds&amp;#39; like Jupiter&amp;#39;s moon Europa could potentially be habitable for life.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.jpl.nasa.gov/images/pia19048-europas-stunning-surface/"&gt;NASA/JPL-Caltech/SETI Institute&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The search for life beyond Earth is a key driver of modern astronomy and planetary science. The U.S. is building multiple major telescopes and planetary probes to advance this search. However, the signs of life – called biosignatures – that scientists may find &lt;a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828"&gt;will likely be difficult to interpret&lt;/a&gt;. Figuring out where exactly to look also remains challenging. &lt;/p&gt;
915.  
916. <p><a href="https://apai.space">I am</a> an <a href="https://scholar.google.com/citations?user=2SCIYjIAAAAJ&hl=en&oi=ao">astrophysicist and astrobiologist</a> with over 20 years of experience studying extrasolar planets – which are planets beyond our solar system.</p>
917.  
918. <p>My colleagues and I have developed a <a href="https://arxiv.org/abs/2505.22808">new approach</a> that will identify the most interesting planets or moons to search for life and help interpret potential biosignatures. We do this by modeling how different organisms may fare in different environments, informed by studies of limits of life on Earth. </p>
919.  
920. <h2>New telescopes to search for life</h2>
921.  
922. <p>Astronomers are developing plans and technology for increasingly powerful space telescopes. For instance, NASA is working on its proposed <a href="https://science.nasa.gov/astrophysics/programs/habitable-worlds-observatory/">Habitable Worlds Observatory</a>, which would take ultrasharp images that directly show the planets orbiting nearby stars. </p>
923.  
924. <p>My colleagues and I are developing another concept, the <a href="https://theconversation.com/a-new-thin-lensed-telescope-design-could-far-surpass-james-webb-goodbye-mirrors-hello-diffractive-lenses-206055">Nautilus</a> space telescope constellation, which is designed to study hundreds of potentially Earthlike planets as they pass in front of their host stars. </p>
925.  
926. <figure class="align-center zoomable">
927.            <a href="https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A number of spherical telescopes next to a spaceship." src="https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=366&fit=crop&dpr=1 754w, https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=366&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/671359/original/file-20250530-56-hovmw.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=366&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
928.            <figcaption>
929.              <span class="caption">Future telescopes, like the proposed Nautilus, could help search the skies for habitable planets.</span>
930.              <span class="attribution"><span class="source">Katie Yung, Daniel Apai /University of Arizona and AllThingsSpace /SketchFab</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
931.            </figcaption>
932.          </figure>
933.  
934. <p>These and other future telescopes aim to provide more sensitive studies of more alien worlds. Their development prompts two important questions: “Where to look?” and “Are the environments where we think we see signs of life actually habitable?”</p>
935.  
936. <p>The strongly disputed claims of potential <a href="https://theconversation.com/scientists-found-a-potential-sign-of-life-on-a-distant-planet-an-astronomer-explains-why-many-are-still-skeptical-254900">signs of life in the exoplanet K2-18b</a>, announced in April 2025, and <a href="https://theconversation.com/the-detection-of-phosphine-in-venus-clouds-is-a-big-deal-heres-how-we-can-find-out-if-its-a-sign-of-life-146185">previous similar claims in Venus</a>, show how difficult it is to conclusively identify the <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">presence of life from remote-sensing data</a>. </p>
937.  
938. <h2>When is an alien world habitable?</h2>
939.  
940. <p><a href="https://languages.oup.com/dictionaries/">Oxford Languages</a> defines “habitable” as “suitable or good enough to live in.” But how do scientists know what is “good enough to live in” for extraterrestrial organisms? Could alien microbes frolic in lakes of boiling acid or frigid liquid methane, or float in water droplets in <a href="https://www.britannica.com/place/Venus-planet/The-atmosphere">Venus’ upper atmosphere</a>?</p>
941.  
942. <p>To keep it simple, NASA’s mantra has been “follow the water.” This makes sense – <a href="https://theconversation.com/water-was-both-essential-and-a-barrier-to-early-life-on-earth-microdroplets-are-one-potential-solution-to-this-paradox-192710">water is essential</a> for all Earth life we know of. A planet with liquid water would also have a temperate environment. It wouldn’t be so cold that it slows down chemical reactions, nor would it be so hot that it destroys the complex molecules necessary for life.</p>
943.  
944. <p>However, with astronomers’ rapidly growing capabilities for characterizing alien worlds, astrobiologists need an approach that is more quantitative and nuanced than the water or no-water classification.</p>
945.  
946. <h2>A community effort</h2>
947.  
948. <p>As part of the NASA-funded <a href="https://alienearths.space">Alien Earths</a> project that I lead, <a href="https://depts.washington.edu/astrobio/wordpress/profile/rory-barnes/">astrobiologist Rory Barnes</a> and I worked on this problem with a group of experts – astrobiologists, planetary scientists, exoplanet experts, ecologists, biologists and chemists – drawn from the largest network of exoplanet and astrobiology researchers, NASA’s Nexus for Exoplanet System Science, or <a href="https://nexss.info">NExSS</a>. </p>
949.  
950. <p>Over a hundred colleagues provided us with ideas, and two questions came up often:</p>
951.  
952. <p>First, <a href="https://theconversation.com/why-do-astronomers-look-for-signs-of-life-on-other-planets-based-on-what-life-is-like-on-earth-227658">how do we know what life needs</a>, if we do not understand the full range of extraterrestrial life? Scientists know a lot about life on Earth, but most astrobiologists agree that more exotic types of life – perhaps based on different combinations of chemical elements and solvents – are possible. How do we determine what conditions those other types of life may require?</p>
953.  
954. <p>Second, the approach has to work with incomplete data. Potential sites for life beyond Earth – “extrasolar habitats” – are very difficult to study directly, and often impossible to visit and sample. </p>
955.  
956. <p>For example, the <a href="https://www.nasa.gov/solar-system/planets/mars/could-life-exist-below-mars-ice-nasa-study-proposes-possibilities/">Martian subsurface</a> remains mostly out of our reach. Places like Jupiter’s moon <a href="https://theconversation.com/jupiters-moons-hide-giant-subsurface-oceans-europa-clipper-is-one-of-2-missions-on-their-way-to-see-if-these-moons-could-support-life-203207">Europa’s</a> and Saturn’s Moon <a href="https://theconversation.com/saturns-ocean-moon-enceladus-is-able-to-support-life-my-research-team-is-working-out-how-to-detect-extraterrestrial-cells-there-226286">Enceladus’ subsurface oceans</a> and all extrasolar planets remain practically unreachable. Scientists study them indirectly, often only using remote observations. These measurements can’t tell you as much as actual samples would. </p>
957.  
958. <figure class="align-center zoomable">
959.            <a href="https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view of Mars' dusty, rocky surface." src="https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=250&fit=crop&dpr=1 600w, https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=250&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=250&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=314&fit=crop&dpr=1 754w, https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=314&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/671382/original/file-20250530-74-i13dts.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=314&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
960.            <figcaption>
961.              <span class="caption">Mars’ hot, dusty surface is hostile for life. But scientists haven’t been able to study whether some organisms could lurk beneath.</span>
962.              <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA16453">NASA/JPL-Caltech/Malin Space Science Systems</a></span>
963.            </figcaption>
964.          </figure>
965.  
966. <p>To make matters worse, measurements often have uncertainties. For example, we may be only 88% confident that water vapor is present in an exoplanet’s atmosphere. Our framework has to be able to work with small amounts of data and handle uncertainties. And, we need to accept that the answers will often not be black or white.</p>
967.  
968. <h2>A new approach to habitability</h2>
969.  
970. <p>The new approach, called the <a href="https://arxiv.org/abs/2505.22808">quantitative habitability framework</a>, has two distinguishing features: </p>
971.  
972. <p>First, we moved away from trying to answer the vague “habitable to life” question and narrowed it to a more specific and practically answerable question: Would the conditions in the habitat – as we know them – allow a specific (known or yet unknown) species or ecosystem to survive? </p>
973.  
974. <p>Even on Earth, organisms require different conditions to survive – there are no camels in Antarctica. By talking about specific organisms, we made the question easier to answer.</p>
975.  
976. <p>Second, the quantitative habitability framework does not insist on black-or-white answers. It compares computer models to calculate a probabilistic answer. Instead of assuming that liquid water is a key limiting factor, we compare our understanding of the conditions an organism requires (the “organism model”) with our understanding of the conditions present in the environment (the “habitat model”). </p>
977.  
978. <p>Both have uncertainties. Our understanding of each can be incomplete. Yet, we can handle the uncertainties mathematically. By comparing the two models, we can determine the probability that an organism and a habitat are compatible. </p>
979.  
980. <p>As a simplistic example, our habitat model for Antarctica may state that temperatures are often below freezing. And our organism model for a camel may state that it does not survive long in cold temperatures. Unsurprisingly, we would correctly predict a near-zero probability that Antarctica is a good habitat for camels. </p>
981.  
982. <figure class="align-right zoomable">
983.            <a href="https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of thick plumes of smoke coming from rocks under the sea." src="https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=884&fit=crop&dpr=1 600w, https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=884&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=884&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=1111&fit=crop&dpr=1 754w, https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=1111&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/670827/original/file-20250528-56-oaf50b.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=1111&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
984.            <figcaption>
985.              <span class="caption">A hydrothermal vent deep in the Atlantic Ocean. These vents discharge incredibly hot plumes of water, but some host hearty microorganisms.</span>
986.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Hydrothermal_vent#/media/File:Blacksmoker_in_Atlantic_Ocean.jpg">P. Rona / OAR/National Undersea Research Program (NURP); NOAA</a></span>
987.            </figcaption>
988.          </figure>
989.  
990. <p>We had a blast working on this project. To study the limits of life, we collected literature data on extreme organisms, from insects that live in the Himalayas at high altitudes and low temperatures to microorganisms that flourish in <a href="https://education.nationalgeographic.org/resource/deep-sea-hydrothermal-vents/">hydrothermal vents on the ocean floor</a> and feed on chemical energy. </p>
991.  
992. <p>We explored, via our models, whether they may survive in the Martian subsurface or in Europa’s oceans. We also investigated if marine bacteria that produce oxygen in Earth’s oceans could potentially survive on known extrasolar planets. </p>
993.  
994. <p>Although comprehensive and detailed, this approach makes important simplifications. For example, it does not yet model how life may shape the planet, nor does it account for the full array of nutrients organisms may need. These simplifications are by design. </p>
995.  
996. <p>In most of the environments we currently study, we know too little about the conditions to meaningfully attempt such models – except for some solar system bodies, such as <a href="https://doi.org/10.1038/s41550-021-01372-6">Saturn’s Enceladus</a>. </p>
997.  
998. <p>The quantitative habitability framework allows my team to answer questions like whether astrobiologists might be interested in a subsurface location on Mars, given the available data, or whether astronomers should turn their telescopes to planet A or planet B while searching for life. Our framework is available as an open-source computer model, which astrobiologists can now readily use and further develop to help with current and future projects.</p>
999.  
1000. <p>If scientists do detect a potential signature of life, this approach can help assess if the environment where it is detected can actually support the type of life that leads to the signature detected. </p>
1001.  
1002. <p>Our next steps will be to build a database of terrestrial organisms that live in extreme environments and represent the limits of life. To this data, we can also add models for hypothetical alien life. By integrating those into the quantitative habitability framework, we will be able to work out scenarios, interpret new data coming from other worlds and guide the search for signatures of life beyond Earth – in our solar system and beyond.</p><img src="https://counter.theconversation.com/content/256427/count.gif" alt="The Conversation" width="1" height="1" />
1003. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Daniel Apai receives funding from NASA, Heising-Simons Foundation, Department of Defense, Space Telescope Science Institute, and the University of Arizona, and leads the NASA-funded Alien Earths astrobiology research team that developed the framework described here. He is affiliated with the Steward Observatory and Lunar and Planetary Laboratory of The University of Arizona. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1004.    <summary>As NASA rolls out more powerful telescopes in the future, scientists will need a way to determine where to point them. A new approach could help.</summary>
1005.    <author>
1006.      <name>Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona</name>
1007.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/daniel-apai-555353"/>
1008.    </author>
1009.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1010.  </entry>
1011.  <entry>
1012.    <id>tag:theconversation.com,2011:article/256797</id>
1013.    <published>2025-05-28T20:24:19Z</published>
1014.    <updated>2025-05-28T20:24:19Z</updated>
1015.    <link rel="alternate" type="text/html" href="https://theconversation.com/x-rays-have-revealed-a-mysterious-cosmic-object-never-before-seen-in-our-galaxy-256797"/>
1016.    <title>X-rays have revealed a mysterious cosmic object never before seen in our galaxy</title>
1017.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/668558/original/file-20250518-56-pcosxw.png?ixlib=rb-4.1.0&amp;amp;rect=0%2C577%2C1799%2C1012&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Author provided&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;In a new study published today in &lt;a href="https://www.nature.com/articles/s41586-025-09077-w"&gt;Nature&lt;/a&gt;, we report the discovery of a new long-period transient – and, for the first time, one that also emits regular bursts of X-rays.&lt;/p&gt;
1018.  
1019. <p>Long-period transients are a <a href="https://theconversation.com/this-object-in-space-flashed-brilliantly-for-3-months-then-disappeared-astronomers-are-intrigued-175240">recently identified</a> class of cosmic objects that emit bright flashes of radio waves every few minutes to several hours. This is much longer than the rapid pulses we typically detect from <a href="https://www.space.com/32661-pulsars.html">dead stars</a> such as pulsars.</p>
1020.  
1021. <p>What these objects are, and how they generate their unusual signals, remains a mystery.</p>
1022.  
1023. <p>Our discovery opens up a new window into the study of these puzzling sources. But it also deepens the mystery: the object we found doesn’t resemble any known type of star or system in our galaxy – or beyond.</p>
1024.  
1025. <figure class="align-center zoomable">
1026.            <a href="https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668556/original/file-20250518-56-984k4o.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1027.            <figcaption>
1028.              <span class="caption">An image of the sky showing the region around ASKAP J1832-0911. The yellow circle marks the position of the newly discovered source. This image shows X-rays from NASA’s Chandra X-ray Observatory, radio data from the South African MeerKAT radio telescope, and infrared data from NASA’s Spitzer Space Telescope.</span>
1029.              <span class="attribution"><span class="source">Author provided</span></span>
1030.            </figcaption>
1031.          </figure>
1032.  
1033. <h2>Watching the radio sky for flickers</h2>
1034.  
1035. <p>There’s much in the night sky that we can’t see with human eyes but can detect when we look at other wavelengths, such as radio emissions. </p>
1036.  
1037. <p>Our research team regularly scans the radio sky using the Australian SKA Pathfinder (<a href="https://www.csiro.au/en/about/facilities-collections/atnf/askap-radio-telescope">ASKAP</a>), operated by CSIRO on Wajarri Yamaji Country in Western Australia. Our goal is to find cosmic objects that appear and disappear (known as transients).</p>
1038.  
1039. <p>Transients are often linked to some of the most powerful and dramatic events in the universe, such as the explosive deaths of stars. </p>
1040.  
1041. <p>In late 2023, we spotted an extremely bright source, named ASKAP J1832-0911 (based on its position in the sky), in the direction of the galactic plane. This object is located about 15,000 light years away. This is far, but still within the Milky Way. </p>
1042.  
1043. <figure class="align-center zoomable">
1044.            <a href="https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An overhead view of large white radio dishes under a bright blue sky littered with clouds and a red earth underneath." src="https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/670227/original/file-20250526-62-ryyiof.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1045.            <figcaption>
1046.              <span class="caption">Some of the ASKAP antennas, located at Inyarrimanha Ilgari Bundara, the Murchison Radio-astronomy Observatory in Western Australia.</span>
1047.              <span class="attribution"><span class="source">CSIRO</span></span>
1048.            </figcaption>
1049.          </figure>
1050.  
1051. <h2>A dramatic event</h2>
1052.  
1053. <p>After the initial discovery, we began follow-up observations using telescopes around the world, hoping to catch more pulses. With continued monitoring, we found the radio pulses from ASKAPJ1832 arrive regularly – every 44 minutes. This confirmed it as a new member of the rare long-period transient group.</p>
1054.  
1055. <p>But we did not just look forward in time – we also looked back. We searched through older telescope data from the same part of the sky. We found no trace of the object before the discovery.</p>
1056.  
1057. <p>This suggests something dramatic happened shortly before we first detected it – something powerful enough to suddenly switch the object “on”.</p>
1058.  
1059. <p>Then, in February 2024, ASKAPJ1832 became extremely active. After a quieter period in January, the source brightened dramatically. Fewer than 30 objects in the sky have ever reached such brightness in radio waves.</p>
1060.  
1061. <p>For comparison, most stars we detect in radio are about 10,000 times fainter than ASKAPJ1832 during that flare-up.</p>
1062.  
1063. <h2>A lucky break</h2>
1064.  
1065. <p><a href="https://www.space.com/electromagnetic-spectrum-use-in-astronomy#section-what-do-x-rays-teach-us-about-the-universe">X-rays</a> are a form of light that we can’t see with our eyes. They usually come from extremely hot and energetic environments. Although about ten similar radio-emitting objects have been found so far, none had ever shown X-ray signals.</p>
1066.  
1067. <p>In March, we tried to observe ASKAPJ1832 in X-rays. However, due to <a href="https://phys.org/news/2024-03-nasa-swift-temporarily-science.html">technical issues</a> with the telescope, the observation could not go ahead. </p>
1068.  
1069. <p>Then came a stroke of luck. In June, I reached out to my friend Tong Bao, a postdoctoral researcher at the Italian National Institute for Astrophysics, to check if any previous X-ray observations had captured the source. To our surprise, we found two past observations from <a href="https://www.nasa.gov/mission/chandra-x-ray-observatory/">NASA’s Chandra X-ray Observatory</a>, although the data were still under a proprietary period (not yet public).</p>
1070.  
1071. <p>We contacted Kaya Mori, a research scientist at Columbia University and the principal investigator of those observations. He generously shared the data with us. To our amazement, we discovered clear X-ray signals coming from ASKAPJ1832. Even more remarkable: the X-rays followed the same 44-minute cycle as the radio pulses.</p>
1072.  
1073. <p>It was a truly lucky break. Chandra had been pointed at a different target entirely, but by pure coincidence, it caught ASKAPJ1832 during its unusually bright and active phase.</p>
1074.  
1075. <p>A chance alignment like that is incredibly rare – like finding a needle in a cosmic haystack.</p>
1076.  
1077. <figure class="align-center zoomable">
1078.            <a href="https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Artwork of a tube-shaped telescope in space with large solar panel arrays on one end." src="https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/670228/original/file-20250526-56-iztq8q.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1079.            <figcaption>
1080.              <span class="caption">NASA’s Chandra X-ray Observatory is the world’s most powerful X-ray telescope, in orbit around Earth since 1999.</span>
1081.              <span class="attribution"><a class="source" href="https://www.nasa.gov/chandra-overview/">NASA/CXC & J. Vaughan</a></span>
1082.            </figcaption>
1083.          </figure>
1084.  
1085. <h2>Still a mystery</h2>
1086.  
1087. <p>Having both radio and X-ray bursts is a common trait of dead stars with extremely strong magnetic fields, such as neutron stars (high-mass dead stars) and white dwarf (low-mass dead stars).</p>
1088.  
1089. <p>Our discovery suggests that at least some long-period transients may come from these kinds of stellar remnants.</p>
1090.  
1091. <p>But ASKAPJ1832 does not quite fit into any known category of object in our galaxy. Its behaviour, while similar in some ways, still breaks the mould.</p>
1092.  
1093. <p>We need more observations to truly understand what is going on. It is possible that ASKAPJ1832 is something entirely new, or it could be emitting radio waves in a way we have never seen before.</p><img src="https://counter.theconversation.com/content/256797/count.gif" alt="The Conversation" width="1" height="1" />
1094. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Ziteng Wang does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1095.    <summary>The object doesn’t resemble any known type of star or system in the Milky Way.</summary>
1096.    <author>
1097.      <name>Ziteng Wang, Associate Lecturer, Curtin Institute of Radio Astronomy (CIRA), Curtin University</name>
1098.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/ziteng-wang-1270500"/>
1099.    </author>
1100.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1101.  </entry>
1102.  <entry>
1103.    <id>tag:theconversation.com,2011:article/257011</id>
1104.    <published>2025-05-20T20:20:34Z</published>
1105.    <updated>2025-05-20T20:20:34Z</updated>
1106.    <link rel="alternate" type="text/html" href="https://theconversation.com/for-making-stars-its-not-just-how-much-gas-a-galaxy-has-that-matters-its-where-its-hiding-257011"/>
1107.    <title>For making stars, it’s not just how much gas a galaxy has that matters – it’s where it’s hiding</title>
1108.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/668656/original/file-20250519-56-gl8hfz.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C364%2C1666%2C937&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;One of the galaxies mapped by WALLABY: the red shade shows the atomic hydrogen gas content of the galaxy, overlaid on an optical image showing the stars. Much of it is typically found beyond the stellar disk (thin white line), where star formation takes place.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Legacy Surveys / D. Lang (Perimeter Institute) / T. Westmeier &lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Galaxies are often described as vast star factories, churning out new suns from clouds of gas. For decades, astronomers have assumed that the more raw material a galaxy holds, the more stars it should be able to make.&lt;/p&gt;
1109.  
1110. <p>But <a href="https://doi.org/10.1017/pasa.2025.30">our latest study</a>, published this month in the Publications of the Astronomical Society of Australia (PASA), challenges that assumption. We found that when it comes to forming stars, it’s not just the amount of gas in a galaxy that matters – it’s where that gas is located.</p>
1111.  
1112. <h2>Getting the ingredients in the right place</h2>
1113.  
1114. <p>Our research is part of one of the largest efforts to map atomic hydrogen gas in nearby galaxies. This huge project is called the <a href="https://wallaby-survey.org">WALLABY survey</a> (or the Widefield ASKAP L-band Legacy All-sky Blind Survey). </p>
1115.  
1116. <p>Hydrogen is the most abundant element in the universe and the basic building block of stars. But surprisingly, a large fraction of this gas in galaxies lies far from where stars actually form – out in the faint outer regions, well beyond the bright stellar disk.</p>
1117.  
1118. <p>Think of atomic hydrogen as the flour in a cake recipe. It’s the essential ingredient for making stars. But what really matters for the recipe is not how much flour there is in the bag, but how much ends up in the mixing bowl. </p>
1119.  
1120. <p>In the same way, to understand how stars form, we need to focus on the gas that’s in the right place. In a galaxy, that means within the stellar disk, where it can actually be used.</p>
1121.  
1122. <h2>A closer look</h2>
1123.  
1124. <p>Until now, most measurements of atomic hydrogen in galaxies have <a href="https://ui.adsabs.harvard.edu/abs/2022ARA%26A..60..319S/abstract">focused on their total gas content</a>, without showing where that gas is located. That’s because earlier observations – especially those made with single-dish radio telescopes – couldn’t detect where in a galaxy hydrogen gas was located.</p>
1125.  
1126. <p>However, the <a href="https://www.csiro.au/en/about/facilities-collections/ATNF/ASKAP-radio-telescope">Australian Square Kilometre Array Pathfinder (ASKAP)</a> telescope in Western Australia has a very wide field of view and moderate resolution. This means astronomers can use it to efficiently map the hydrogen gas across large areas of the sky and within individual galaxies. </p>
1127.  
1128. <p>Using the ASKAP telescope, the WALLABY survey should eventually detect more than 200,000 galaxies and provide detailed hydrogen maps for many thousands of them. </p>
1129.  
1130. <h2>A puzzle resolved</h2>
1131.  
1132. <p>Our study, led by PhD student Seona Lee, draws on hydrogen maps for around 1,000 galaxies. This is an unprecedented sample size for this kind of analysis. </p>
1133.  
1134. <p>The results reveal a clear trend. The amount of star formation is much more closely linked to the amount of hydrogen gas within the stellar disk than the gas farther out. That outer gas, even when it is plentiful, appears to play little immediate role in fuelling new stars.</p>
1135.  
1136. <p>This helps explain a long-standing puzzle – why some galaxies with large gas reservoirs form relatively few stars. It turns out much of their gas may be sitting idle in the galactic outskirts, too far from the regions where stars actually form.</p>
1137.  
1138. <p>In short, measuring the total gas content of a galaxy doesn’t give the full picture. To understand star formation, we need to zoom in – not just total up the ingredients, but see  where they’re actually being used.</p><img src="https://counter.theconversation.com/content/257011/count.gif" alt="The Conversation" width="1" height="1" />
1139. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1140.    <summary>A new, more detailed study of 1,000 distant galaxies explains why some gas-rich galaxies don’t produce as many stars as you’d expect.</summary>
1141.    <author>
1142.      <name>Barbara Catinella, Professor and Senior Principal Research Fellow, International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia</name>
1143.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/barbara-catinella-2396729"/>
1144.    </author>
1145.    <author>
1146.      <name>Seona Lee, PhD student, International Centre for Radio Astronomy Research, The University of Western Australia</name>
1147.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/seona-lee-2396777"/>
1148.    </author>
1149.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1150.  </entry>
1151.  <entry>
1152.    <id>tag:theconversation.com,2011:article/252880</id>
1153.    <published>2025-05-20T12:40:39Z</published>
1154.    <updated>2025-05-20T12:40:39Z</updated>
1155.    <link rel="alternate" type="text/html" href="https://theconversation.com/do-photons-wear-out-an-astrophysicist-explains-lights-ability-to-travel-vast-cosmic-distances-without-losing-energy-252880"/>
1156.    <title>Do photons wear out? An astrophysicist explains light’s ability to travel vast cosmic distances without losing energy</title>
1157.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/665882/original/file-20250505-62-3pk41.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C268%2C8451%2C4753&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Light, whether from a star or your flashlight, travels at 186,000 miles per second.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.gettyimages.com/detail/photo/abstract-picture-of-colorful-light-trails-crossing-royalty-free-image/1223224921"&gt;Artur Debat/Moment via Getty Images&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, walked up just as the first space photo streamed to my tablet. It sparkled on the screen in front of us.&lt;/p&gt;
1158.  
1159. <p>“That’s the <a href="https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-101/">Pinwheel galaxy</a>,” I said. The name is derived from its shape – albeit this pinwheel contains about a trillion stars. </p>
1160.  
1161. <p>The light from the Pinwheel traveled for 25 million years across the universe – about 150 quintillion miles – to get to my telescope. </p>
1162.  
1163. <p>My wife wondered: “Doesn’t light get tired during such a long journey?”</p>
1164.  
1165. <p>Her curiosity triggered a thought-provoking conversation about light. Ultimately, why doesn’t light wear out and lose energy over time?</p>
1166.  
1167. <h2>Let’s talk about light</h2>
1168.  
1169. <p>I am an <a href="https://scholar.google.com.hk/citations?user=kR9BWlYAAAAJ">astrophysicist</a>, and one of the first things I learned in my studies is how light often behaves in ways that defy our intuitions. </p>
1170.  
1171. <figure class="align-right zoomable">
1172.            <a href="https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of outer space that shows a galaxy shaped like a pinwheel." src="https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=648&fit=crop&dpr=1 600w, https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=648&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=648&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=814&fit=crop&dpr=1 754w, https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=814&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/667702/original/file-20250513-56-menm5r.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=814&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1173.            <figcaption>
1174.              <span class="caption">The author’s photo of the Pinwheel galaxy.</span>
1175.              <span class="attribution"><a class="source" href="https://Author%20provided">Jarred Roberts</a></span>
1176.            </figcaption>
1177.          </figure>
1178.  
1179. <p>Light is <a href="https://science.nasa.gov/ems/02_anatomy/">electromagnetic radiation</a>: basically, an electric wave and a magnetic wave coupled together and traveling through <a href="https://www.symmetrymagazine.org/article/spacetime-all-the-universes-a-stage?language_content_entity=und">space-time</a>. It <a href="https://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html">has no mass</a>. That point is critical because the mass of an object, whether a speck of dust or a spaceship, limits the top speed it can travel through space. </p>
1180.  
1181. <p>But because light is massless, it’s able to reach the maximum speed limit in a vacuum – about 186,000 miles (300,000 kilometers) per second, or <a href="https://blair.pha.jhu.edu/spectroscopy/basics.html">almost 6 trillion miles per year</a> (9.6 trillion kilometers). Nothing traveling through space is faster. To put that into perspective: In the time it takes you to blink your eyes, a particle of light travels around the circumference of the Earth more than twice.</p>
1182.  
1183. <p>As incredibly fast as that is, space is incredibly spread out. Light from the Sun, which is 93 million miles (about 150 million kilometers) from Earth, takes just over <a href="https://phys.org/news/2013-04-sunlight-earth.html#:%7E">eight minutes to reach us</a>. In other words, the sunlight you see is eight minutes old.</p>
1184.  
1185. <p><a href="https://svs.gsfc.nasa.gov/20377">Alpha Centauri</a>, the nearest star to us after the Sun, is 26 trillion miles away (about 41 trillion kilometers). So by the time you see it in the night sky, its light is just over four years old. Or, as astronomers say, it’s <a href="https://spaceplace.nasa.gov/light-year/en/">four light years away</a>.</p>
1186.  
1187. <figure>
1188.            <iframe width="440" height="260" src="https://www.youtube.com/embed/1BTxxJr8awQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1189.            <figcaption><span class="caption">Imagine – a trip around the world at the speed of light.</span></figcaption>
1190.          </figure>
1191.  
1192. <p>With those enormous distances in mind, consider Cristina’s question: How can light travel across the universe and not slowly lose energy? </p>
1193.  
1194. <p>Actually, some light does lose energy. This happens when <a href="https://science.nasa.gov/ems/03_behaviors/">it bounces off something</a>, such as interstellar dust, and is scattered about. </p>
1195.  
1196. <p>But most light just goes and goes, without colliding with anything. This is almost always the case because <a href="https://science.howstuffworks.com/dictionary/astronomy-terms/question221.htm#:%7E">space is mostly empty</a> – nothingness. So there’s nothing in the way. </p>
1197.  
1198. <p>When light travels unimpeded, it loses no energy. It can maintain that 186,000-mile-per-second speed forever. </p>
1199.  
1200. <h2>It’s about time</h2>
1201.  
1202. <p>Here’s another concept: Picture yourself as an astronaut <a href="https://www.nasa.gov/international-space-station/space-station-facts-and-figures/">on board the International Space Station</a>. You’re orbiting at 17,000 miles (about 27,000 kilometers) per hour. Compared with someone on Earth, your wristwatch will tick 0.01 seconds slower over one year. </p>
1203.  
1204. <p>That’s an example of <a href="https://www.livescience.com/what-is-time-dilation">time dilation</a> – time moving at <a href="https://www.nasa.gov/image-article/einsteins-theory-of-relativity-critical-gps-seen-distant-stars/">different speeds under different conditions</a>. If you’re moving really fast, or close to a large gravitational field, your clock will tick more slowly than someone moving slower than you, or who is further from a large gravitational field. To say it succinctly, <a href="https://www.space.com/36273-theory-special-relativity.html">time is relative</a>. </p>
1205.  
1206. <figure class="align-center zoomable">
1207.            <a href="https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An astronaut floats weightless aboard the International Space Station." src="https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/668490/original/file-20250516-62-xhfcdu.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1208.            <figcaption>
1209.              <span class="caption">Even astronauts aboard the International Space Station experience time dilation, although the effect is extremely small.</span>
1210.              <span class="attribution"><a class="source" href="https://images-assets.nasa.gov/image/iss072e861730/iss072e861730~large.jpg?w=1920&h=1280&fit=clip&crop=faces%2Cfocalpoint">NASA</a></span>
1211.            </figcaption>
1212.          </figure>
1213.  
1214. <p>Now consider that light is <a href="https://pcos.gsfc.nasa.gov/science/relativity.php">inextricably connected to time</a>.
1215. Picture sitting on a <a href="https://www.symmetrymagazine.org/article/what-is-a-photon?language_content_entity=und">photon</a>, a fundamental particle of light; here, you’d experience maximum time dilation. Everyone on Earth would clock you at the speed of light, but from your reference frame, time would completely stop. </p>
1216.  
1217. <p>That’s because the “clocks” measuring time are in two different places going vastly different speeds: the photon moving at the speed of light, and the comparatively slowpoke speed of Earth going around the Sun. </p>
1218.  
1219. <p>What’s more, when you’re traveling at or close to the speed of light, the distance between where you are and where you’re going gets shorter. That is, space itself becomes more compact in the direction of motion – so the faster you can go, the shorter your journey has to be. In other words, for the photon, <a href="https://ocw.mit.edu/courses/8-022-physics-ii-electricity-and-magnetism-fall-2004/f8cd941a21a671e60cc66ba76c395896_relativity.pdf">space gets squished</a>. </p>
1220.  
1221. <p>Which brings us back to my picture of the Pinwheel galaxy. From the photon’s perspective, a star within the galaxy emitted it, and then a single pixel in my backyard camera absorbed it, at exactly the same time. Because space is squished, to the photon the journey was infinitely fast and infinitely short, a tiny fraction of a second. </p>
1222.  
1223. <p>But from our perspective on Earth, the photon left the galaxy 25 million years ago and traveled 25 million light years across space until it landed on my tablet in my backyard. </p>
1224.  
1225. <p>And there, on a cool spring night, its stunning image inspired a delightful conversation between a nerdy scientist and his curious wife.</p><img src="https://counter.theconversation.com/content/252880/count.gif" alt="The Conversation" width="1" height="1" />
1226. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Jarred Roberts receives funding from NASA. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1227.    <summary>The speed of light is the fastest anything can travel. What happens to a photon from a galaxy 25 million light years away on its journey toward Earth?</summary>
1228.    <author>
1229.      <name>Jarred Roberts, Project Scientist, University of California, San Diego</name>
1230.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/jarred-roberts-2352553"/>
1231.    </author>
1232.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1233.  </entry>
1234.  <entry>
1235.    <id>tag:theconversation.com,2011:article/254257</id>
1236.    <published>2025-05-05T12:33:17Z</published>
1237.    <updated>2025-05-05T12:33:17Z</updated>
1238.    <link rel="alternate" type="text/html" href="https://theconversation.com/how-was-the-earth-built-254257"/>
1239.    <title>How was the Earth built?</title>
1240.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/661438/original/file-20250412-56-2n0jkr.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C4268%2C2395&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The Earth formed in a ring of debris around the Sun, like the one around Vega, a bright star, in this artist&amp;#39;s conception.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://d2pn8kiwq2w21t.cloudfront.net/original_images/jpegPIA16610.jpg"&gt;NASA/JPL-Caltech&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;
1241.  
1242. <p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>.</em></p>
1243.  
1244. <hr>
1245.  
1246. <blockquote>
1247. <p><strong>How was the Earth built? – Noah, age 5, Florida</strong></p>
1248. </blockquote>
1249.  
1250. <hr>
1251.  
1252. <p>It isn’t easy to figure out how the Earth was built, because it happened 4½ billion years ago, and no one was there to watch. So scientists have had to look at what the Earth looks like now and at all of the other planets, moons and debris in the solar system. </p>
1253.  
1254. <p>They’ve concluded that the Earth was built in the same way that you would build a big snowball to make a snowman. The mass that would become our home rolled through planetary debris – rocks floating in space – for more than 100 million years, adding more and more material, until it <a href="https://www.earthfacts.com/space/protoplanettheoryearthformation/">grew into a full-size planet</a>.</p>
1255.  
1256. <p>How do <a href="https://www.researchgate.net/profile/Alexander-Gates">scientists like me</a> know this is what happened? First, studies of the <a href="https://www.sciencefocus.com/planet-earth/rewriting-origin-story-of-earth">size, composition and location of asteroids and comets</a>, many of which are as old as the Earth, indicate that 4½ billion years ago the solar system looked <a href="https://science.nasa.gov/saturn/facts/">the way Saturn looks today</a>, with rings of space rocks orbiting around the Sun. There’s still one such ring around the Sun – it’s called the <a href="https://science.nasa.gov/solar-system/asteroids/facts/">asteroid belt</a> and lies between Mars and Jupiter, with the Sun’s gravity holding the rocks in orbit. </p>
1257.  
1258. <figure>
1259.            <iframe width="440" height="260" src="https://www.youtube.com/embed/WBci287icYM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1260.            <figcaption><span class="caption">The solar system that includes Earth formed from a spinning disk of dust and gases.</span></figcaption>
1261.          </figure>
1262.  
1263. <p>All of the other bodies that we know as planets today began as similar rings of space debris. An <a href="https://www.merriam-webster.com/dictionary/eddy">eddy, or area of rolling</a>, developed in each of these rings and caused the debris to clump up in a snowball effect. But these pieces of debris were asteroids that smashed violently into the growing planets. </p>
1264.  
1265. <p>We can <a href="https://www.lpi.usra.edu/education/explore/shaping_the_planets/impact-cratering/">see those impacts</a> on planets and moons whose surfaces haven’t weathered or reformed. If you look at <a href="https://science.nasa.gov/moon/">the Moon</a> or <a href="https://science.nasa.gov/mercury/facts/">the planet Mercury</a>, you can see that they are covered with craters from asteroid impacts. </p>
1266.  
1267. <p>When asteroids or comets struck these building planets, they crashed into their surfaces at speeds as high as <a href="https://www.lpi.usra.edu/exploration/training/illustrations/craterMechanics/">40,000 to 50,000 miles per hour</a> (65,000 to 80,000 kilometers per hour). The impacts caused huge explosions that emitted massive amounts of dust and broken or melted rock. </p>
1268.  
1269. <p>In fact, scientists believe that the Moon was once part of the Earth, until a large asteroid crashed into the Earth so hard that the Moon broke away and shot into space. There, it began <a href="https://www.history.com/articles/7-major-asteroids-strikes-in-earths-history">orbiting the Earth</a> as it does now. </p>
1270.  
1271. <h2>Still under construction</h2>
1272.  
1273. <p>Most big asteroids and comets collided with the Earth when it was young, about 4½ billion years ago. The number of such collisions has steadily decreased ever since. However, <a href="https://www.astronomy.com/science/how-much-dust-falls-on-earth-each-year-does-it-affect-our-planets-gravity/">at least 100 tons</a> of dust-size space rock rains down on the Earth every day, increasing the size of our planet bit by bit. </p>
1274.  
1275. <p>The Earth also collides with space rocks, called meteors, that show up as shooting stars in the night sky. Some of these meteors come from <a href="https://www.amnh.org/exhibitions/permanent/meteorites/building-planets/mars">an impact that struck Mars</a> at some point, breaking away rock from the planet surface and shooting it into outer space. These rocks have been <a href="https://naturalhistory.si.edu/education/teaching-resources/earth-science/meteorites-messengers-outer-space">falling to Earth</a> ever since.</p>
1276.  
1277. <p>What’s the difference between an asteroid and a comet? Asteroids are large space rocks, while comets are large, dirty ice balls. Meteors are smaller − typically the size of pebbles or even dust. </p>
1278.  
1279. <p>About 65 million years ago, a huge asteroid struck the Earth in the Gulf of Mexico. The enormous <a href="https://www.history.com/articles/7-major-asteroids-strikes-in-earths-history">Chicxulub explosion</a> drove large tsunamis throughout the ocean and raised so much dust into the air that it made the dinosaurs go extinct. </p>
1280.  
1281. <p>Another large asteroid impact, about 35 million years ago, made a huge crater in the area that is now the <a href="https://www.history.com/articles/7-major-asteroids-strikes-in-earths-history">Chesapeake Bay</a>, near Washington, D.C. More recently, in 1908, an asteroid likely exploded over <a href="https://www.history.com/articles/7-major-asteroids-strikes-in-earths-history">Tunguska, Russia</a>, flattening 830 square miles (2,150 square kilometers) of trees. Fortunately, no one lived in the area, so there were no known casualties. </p>
1282.  
1283. <figure class="align-center zoomable">
1284.            <a href="https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large crater with a raised rim in the middle of desert terrain." src="https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/661436/original/file-20250412-62-c5cik1.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1285.            <figcaption>
1286.              <span class="caption">Barringer Crater in Arizona was caused by a meteor strike about 50,000 years ago. It measures about 0.75 miles (1.2 kilometers) across.</span>
1287.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System#/media/File:Barringer_Crater_aerial_photo_by_USGS.jpg">D. Roddy, USGS/Wikipedia</a></span>
1288.            </figcaption>
1289.          </figure>
1290.  
1291. <p>Once a mass of space debris was assembled into the Earth, many processes continued to shape the planet’s surface. Wind, water, heat and cold cause rocks to <a href="https://ugc.berkeley.edu/background-content/weathering/">weather and break down</a> and <a href="https://ugc.berkeley.edu/background-content/erosion/">soil to erode</a>. <a href="https://ugc.berkeley.edu/background-content/erosion/">Mountains are created</a> as pieces of Earth’s crust collide and crack. Rivers and glaciers wear down the planet’s surface to make it smoother. </p>
1292.  
1293. <p>The Earth is a dynamic planet that is constantly being built, and these processes will continue for billions of years into the future. </p>
1294.  
1295. <hr>
1296.  
1297. <p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
1298.  
1299. <p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/254257/count.gif" alt="The Conversation" width="1" height="1" />
1300. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Alexander E. Gates does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1301.    <summary>The Earth started as a mixture of gas and dust around the Sun and grew as it collided with asteroids and dust particles.</summary>
1302.    <author>
1303.      <name>Alexander E. Gates, Professor of Earth and Environmental Science, Rutgers University - Newark</name>
1304.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/alexander-e-gates-1628865"/>
1305.    </author>
1306.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1307.  </entry>
1308.  <entry>
1309.    <id>tag:theconversation.com,2011:article/243022</id>
1310.    <published>2025-04-21T09:09:14Z</published>
1311.    <updated>2025-04-21T09:09:14Z</updated>
1312.    <link rel="alternate" type="text/html" href="https://theconversation.com/twinkling-star-reveals-the-shocking-secrets-of-turbulent-plasma-in-our-cosmic-neighbourhood-243022"/>
1313.    <title>Twinkling star reveals the shocking secrets of turbulent plasma in our cosmic neighbourhood</title>
1314.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/661914/original/file-20250415-56-2gaikj.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C7680%2C4311&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Artist&amp;#39;s impression of a pulsar bow shock scattering a radio beam.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Carl Knox/Swinburne/OzGrav&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;With the most powerful radio telescope in the southern hemisphere, we have observed a twinkling star and discovered an abundance of mysterious plasma structures in our cosmic neighbourhood.&lt;/p&gt;
1315.  
1316. <p>The plasma structures we see are variations in density or turbulence, akin to interstellar cyclones stirred up by energetic events in the galaxy.</p>
1317.  
1318. <p>The study, <a href="https://www.nature.com/articles/s41550-025-02534-6">published today</a> in Nature Astronomy, also describes the first measurements of plasma layers within an interstellar shock wave that surrounds a pulsar. </p>
1319.  
1320. <p>We now realise our local interstellar medium is filled with these structures and our findings also include a rare phenomenon that will challenge theories of pulsar shock waves.</p>
1321.  
1322. <h2>What’s a pulsar and why does it have a shock wave?</h2>
1323.  
1324. <p>Our observations honed in on the nearby fast-spinning pulsar, J0437-4715, which is 512 light-years away from Earth. A pulsar is a <a href="https://theconversation.com/explainer-what-is-a-neutron-star-29341">neutron star</a>, a super-dense stellar remnant that produces beams of radio waves and an energetic “wind” of particles.</p>
1325.  
1326. <p>The pulsar and its wind move with supersonic speed through the interstellar medium – the stuff (gas, dust and plasma) between the stars. This creates a bow shock: a shock wave of heated gas that glows red. </p>
1327.  
1328. <figure>
1329.            <iframe width="440" height="260" src="https://www.youtube.com/embed/gjLk_72V9Bw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1330.            
1331.          </figure>
1332.  
1333. <p>The interstellar plasma is turbulent and scatters pulsar radio waves slightly away from a direct, straight line path. The scattered waves create a pattern of bright and dim patches that drifts over our radio telescopes as Earth, the pulsar and plasma all move through space.</p>
1334.  
1335. <p>From our vantage point, this causes the pulsar to twinkle, or “scintillate”. The effect is similar to how turbulence in Earth’s atmosphere <a href="https://theconversation.com/curious-kids-why-do-stars-twinkle-81188">makes stars twinkle</a> in the night sky. </p>
1336.  
1337. <p>Pulsar scintillation gives us unique information about plasma structures that are too small and faint to be detected in any other way.</p>
1338.  
1339. <h2>Twinkling little radio star</h2>
1340.  
1341. <p>To the naked eye, the twinkling of a star might appear random. But for pulsars at least, there are hidden patterns.</p>
1342.  
1343. <p>With the right techniques, we can uncover ordered shapes from the interference pattern, called scintillation arcs. They detail the locations and velocities of compact structures in the interstellar plasma. Studying scintillation arcs is like performing a CT scan of the interstellar medium – each arc reveals a thin layer of plasma.</p>
1344.  
1345. <p>Usually, scintillation arc studies uncover just one, or at most a handful of these arcs, giving a view of only the most extreme (densest or most turbulent) plasma structures in our galaxy. </p>
1346.  
1347. <p>Our scintillation arc study broke new ground by unveiling an unprecedented 25 scintillation arcs, the most plasma structures observed for any pulsar to date.</p>
1348.  
1349. <p>The sensitivity of our study was only possible because of the close proximity of the pulsar (it’s our <a href="https://theconversation.com/what-happens-when-matter-is-squashed-to-the-brink-of-collapse-we-weighed-a-neutron-star-to-help-nasa-find-out-229813">nearest millisecond pulsar neighbour</a>) and the large collecting area of the <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">MeerKAT radio telescope in South Africa</a>.</p>
1350.  
1351. <figure class="align-center ">
1352.            <img alt="" src="https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=700&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=700&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=700&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=879&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=879&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662138/original/file-20250416-56-tnbkoc.gif?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=879&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
1353.            <figcaption>
1354.              <span class="caption">Animation of 25 scintillation arcs changing in curvature with time according to the changing velocity of the pulsar. Each frame of the animation shows the scintillation arcs measured on one day, for six consecutive days. The inset scintillation arcs originate from the pulsar bow shock.</span>
1355.              <span class="attribution"><a class="source" href="https://www.nature.com/articles/s41550-025-02534-6">Reardon et al., Nature Astronomy</a></span>
1356.            </figcaption>
1357.          </figure>
1358.  
1359. <h2>A Local Bubble surprise</h2>
1360.  
1361. <p>Of the 25 scintillation arcs we found, 21 revealed structures in the interstellar medium. This was surprising because the pulsar – like our own Solar System – is located in a relatively quiet region of our galaxy called the Local Bubble.</p>
1362.  
1363. <p>About <a href="https://www.nature.com/articles/s41586-021-04286-5">14 million years ago</a>, this part of our galaxy was lit up by stellar explosions that swept up material in the interstellar medium and inflated a hot void. Today, this bubble is still expanding and now extends up to 1,000 light-years from us. </p>
1364.  
1365. <p>Our new scintillation arc discoveries reveal that the Local Bubble is not as empty as previously thought. It is filled with compact plasma structures that could only be sustained if the bubble has cooled, at least in some areas, from millions of degrees down to a mild 10,000 degrees Celsius.</p>
1366.  
1367. <h2>Shock discoveries</h2>
1368.  
1369. <p>As the animation below shows, the pulsar is surrounded by its bow shock, which glows red with <a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">light from energised hydrogen atoms</a>.</p>
1370.  
1371. <figure>
1372.            <iframe width="440" height="260" src="https://www.youtube.com/embed/G6UAvud6qVE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1373.            <figcaption><span class="caption">Artist’s animation of the bow shock scattering the pulsar beam. Carl Knox/Swinburne/OzGrav.</span></figcaption>
1374.          </figure>
1375.  
1376. <p>While most pulsars are thought to produce bow shocks, only a handful have ever been observed because they are faint objects. Until now, none had been studied using scintillation.</p>
1377.  
1378. <p>We traced the remaining four scintillation arcs to plasma structures <em>inside</em> the pulsar bow shock, marking the first time astronomers have peered inside one of these shock waves.</p>
1379.  
1380. <p>This gave us a CT-like view of the different layers of plasma. Using these arcs together with an optical image we constructed a new three-dimensional model of the shock, which appears to be tilted slightly away from us because of the motion of the pulsar through space.  </p>
1381.  
1382. <p>The scintillation arcs also gave us the velocities of the plasma layers. Far from being as expected, we discovered that one inner plasma structure is moving towards the shock front against the flow of the shocked material in the opposite direction. </p>
1383.  
1384. <p>While such back flows can appear in simulations, they are rare. This finding will drive new models for this bow shock.</p>
1385.  
1386.  
1387.  
1388. <h2>Scintillating science</h2>
1389.  
1390. <p>With new and more sensitive radio telescopes being built around the world, we can expect to see scintillation from more pulsar bow shocks and other events in the interstellar medium.</p>
1391.  
1392. <p>This will uncover more about the energetic processes in our galaxy that create these otherwise invisible plasma structures.</p>
1393.  
1394. <p>The scintillation of this pulsar neighbour revealed unexpected plasma structures inside our Local Bubble and allowed us to map and measure the speed of plasma within a bow shock. It’s amazing what a twinkling little star can do.</p><img src="https://counter.theconversation.com/content/243022/count.gif" alt="The Conversation" width="1" height="1" />
1395. <p class="fine-print"><em><span>Daniel Reardon receives funding from the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav).
1396.  
1397. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1398.    <summary>For the first time, astronomers have measured the plasma layers of a shock wave surrounding a pulsar.</summary>
1399.    <author>
1400.      <name>Daniel Reardon, Postdoctoral Researcher, Pulsar Timing and Gravitational Waves, Swinburne University of Technology</name>
1401.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/daniel-reardon-1418102"/>
1402.    </author>
1403.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1404.  </entry>
1405.  <entry>
1406.    <id>tag:theconversation.com,2011:article/254900</id>
1407.    <published>2025-04-18T22:44:39Z</published>
1408.    <updated>2025-04-18T22:44:39Z</updated>
1409.    <link rel="alternate" type="text/html" href="https://theconversation.com/scientists-found-a-potential-sign-of-life-on-a-distant-planet-an-astronomer-explains-why-many-are-still-skeptical-254900"/>
1410.    <title>Scientists found a potential sign of life on a distant planet – an astronomer explains why many are still skeptical</title>
1411.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/662692/original/file-20250418-56-at0887.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C1280%2C718&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;An illustration of the exoplanet K2-18b, which some research suggests may be covered by deep oceans. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://webbtelescope.org/contents/media/images/2023/139/01H9R88HG8YXRMARWZ5B1YDT27"&gt;NASA, ESA, CSA, Joseph Olmsted (STScI)&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, &lt;a href="https://doi.org/10.3847/2041-8213/adc1c8"&gt;they had found evidence&lt;/a&gt; for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms. &lt;/p&gt;
1412.  
1413. <p>In April 2024, the <a href="https://science.nasa.gov/mission/webb/">James Webb Space Telescope</a> stared at the host star of the <a href="https://science.nasa.gov/exoplanet-catalog/k2-18-b/">planet K2-18b</a> for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">to the telescope</a>. </p>
1414.  
1415. <figure class="align-center zoomable">
1416.            <a href="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing planets and stars emitting light, which goes through JWST detectors, where it's split into different wavelengths to make a spectrum. Each spectrum suggests the presence of a different element." src="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662693/original/file-20250418-56-afn8ji.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1417.            <figcaption>
1418.              <span class="caption">JWST’s cameras can detect molecules in the atmosphere of a planet by looking at light that passed through that atmosphere.</span>
1419.              <span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2021/06/Spectroscopy_with_Webb">European Space Agency</a></span>
1420.            </figcaption>
1421.          </figure>
1422.  
1423. <p>By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life. </p>
1424.  
1425. <p><a href="https://scholar.google.com/citations?user=2SCIYjIAAAAJ&hl=en">I am an astronomer and astrobiologist</a> who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life. </p>
1426.  
1427. <h2>K2-18b, a mysterious world</h2>
1428.  
1429. <p>To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended <a href="https://science.nasa.gov/mission/kepler/">NASA Kepler mission</a>, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star. </p>
1430.  
1431. <p>K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard.</p>
1432.  
1433. <p>Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about <a href="https://exoplanetarchive.ipac.caltech.edu/overview/K2-18b">eight times more massive than Earth</a>, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense. </p>
1434.  
1435. <p>Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called <a href="https://www.planetary.org/articles/the-skies-of-mini-neptunes">a mini-Neptune</a>, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called <a href="https://www.space.com/26087-gas-dwarf-alien-planets-aas224.html">a gas dwarf</a>. </p>
1436.  
1437. <p>Another option, as <a href="https://scholar.google.co.uk/citations?user=UVxRllsAAAAJ&hl=en">University of Cambridge astronomer Nikku Madhusudhan</a> recently proposed, is that the planet is a “<a href="https://doi.org/10.3847/1538-4357/abfd9c">hycean world</a>.”</p>
1438.  
1439. <p>That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high. </p>
1440.  
1441. <p>Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b.  </p>
1442.  
1443. <p>This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2019.0474">enormous pressures</a>. But a hycean planet would have a large and likely temperate ocean. So could the oceans of <a href="https://earthsky.org/space/hycean-planets-exoplanets-habitability/">hycean worlds be habitable</a> – or even inhabited? </p>
1444.  
1445. <h2>Detecting DMS</h2>
1446.  
1447. <p>In 2023, Madhusudhan and his colleagues used the <a href="https://science.nasa.gov/mission/webb/nircam/">James Webb Space Telescope’s short-wavelength infrared camera</a> to inspect starlight that filtered through K2-18b’s atmosphere for the first time. </p>
1448.  
1449. <p>They found evidence for the <a href="https://doi.org/10.3847/2041-8213/acf577">presence of two simple carbon-bearing molecules</a> – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be <a href="https://doi.org/10.3847/1538-4357/abfd9c">trapped in the deeper and warmer atmosphere</a>, closer to the oceans than the upper atmosphere probed by JWST observations.</p>
1450.  
1451. <p>Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called <a href="https://www.astronomy.com/science/k2-18-b-could-have-dimethyl-sulfide-in-its-air-but-is-it-a-sign-of-life/">dimethyl sulfide</a>, or DMS. On Earth, DMS is produced in <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dimethyl-sulfide">large quantities by marine algae</a>. It has very few, if any, nonbiological sources. </p>
1452.  
1453. <p>This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms. </p>
1454.  
1455. <figure class="align-center zoomable">
1456.            <a href="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of what scientists imagine K2-18b to look like, which looks a little like Earth, with clouds and a translucent surface." src="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/662696/original/file-20250418-56-fwtd80.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1457.            <figcaption>
1458.              <span class="caption">K2-18b could have a deep ocean spanning the planet, and a hydrogen atmosphere.</span>
1459.              <span class="attribution"><a class="source" href="https://www.cam.ac.uk/stories/carbon-found-in-habitable-zone-exoplanet">Amanda Smith, Nikku Madhusudhan (University of Cambridge)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
1460.            </figcaption>
1461.          </figure>
1462.  
1463. <p>Scientists had a <a href="https://bigthink.com/starts-with-a-bang/k2-18b-inhabited/">mixed response</a> to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain. </p>
1464.  
1465. <p>To address these concerns, Mashusudhan’s team turned JWST <a href="https://www.npr.org/2025/04/16/nx-s1-5364805/signs-life-alien-planet-biosignatures-exoplanet">back to K2-18b</a> a year later. This time, they <a href="https://science.nasa.gov/mission/webb/mid-infrared-instrument-miri/">used another camera</a> on JWST that looks for another range of wavelengths of light. <a href="https://doi.org/10.3847/2041-8213/adc1c8">The new results</a> – announced on April 16, 2025 – supported their initial findings. </p>
1466.  
1467. <p>These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger. </p>
1468.  
1469. <p>Madhusudhan’s <a href="https://doi.org/10.3847/2041-8213/adc1c8">team also presented</a> a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting. </p>
1470.  
1471. <h2>Is life out there?</h2>
1472.  
1473. <p>Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure. </p>
1474.  
1475. <p>First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this. </p>
1476.  
1477. <p>Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure. </p>
1478.  
1479. <p>Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility. </p>
1480.  
1481. <p>The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life. </p>
1482.  
1483. <p>Scientists around the world are <a href="https://www.npr.org/2025/04/16/nx-s1-5364805/signs-life-alien-planet-biosignatures-exoplanet">already scrutinizing the published study</a> and will work on new tests of the findings, since independent verification is at the heart of science. </p>
1484.  
1485. <p>Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too. </p>
1486.  
1487. <p>With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility. </p>
1488.  
1489. <p>Regardless of the true nature of K2-18b, the new results show how <a href="https://blogs.nasa.gov/webb/2024/06/05/reconnaissance-of-potentially-habitable-worlds-with-nasas-webb/">using the JWST</a> to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists.</p><img src="https://counter.theconversation.com/content/254900/count.gif" alt="The Conversation" width="1" height="1" />
1490. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Daniel Apai receives funding for astrobiology research from NASA, the Heising-Simons Foundation, and the Gordon and Betty Moore Foundation. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1491.    <summary>The exoplanet K2-18b could harbor a massive ocean, but scientists will need to study the planet more to see if it’s really likely to host life.</summary>
1492.    <author>
1493.      <name>Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona</name>
1494.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/daniel-apai-555353"/>
1495.    </author>
1496.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1497.  </entry>
1498.  <entry>
1499.    <id>tag:theconversation.com,2011:article/254404</id>
1500.    <published>2025-04-15T12:41:08Z</published>
1501.    <updated>2025-04-15T12:41:08Z</updated>
1502.    <link rel="alternate" type="text/html" href="https://theconversation.com/mysterious-objects-from-other-stars-are-passing-through-our-solar-system-scientists-are-planning-missions-to-study-them-up-close-254404"/>
1503.    <title>Mysterious objects from other stars are passing through our solar system. Scientists are planning missions to study them up close</title>
1504.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/661267/original/file-20250411-62-d11epe.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C110%2C1768%2C1009&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.nasa.gov/news-release/our-solar-systems-first-known-interstellar-object-gets-unexpected-speed-boost/"&gt;NASA/ESA/STScI&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;In late 2017, a mysterious object &lt;a href="https://science.nasa.gov/solar-system/comets/oumuamua/"&gt;tore through&lt;/a&gt; our solar system at breakneck speed. Astronomers scrambled to observe the fast moving body using the world’s most powerful telescopes. It was found to be one quarter mile (400m) long and very elongated – perhaps 10 times as long as it was wide. Researchers named it ‘Oumuamua, Hawaiian for “scout”. &lt;/p&gt;
1505.  
1506. <p>'Oumuamua was later confirmed to be the first object from another star known to have visited our solar system. While these interstellar objects (ISO) originate around a star, they end up as cosmic nomads, wandering through space. They are essentially <a href="https://www.aanda.org/articles/aa/full_html/2021/07/aa40587-21/aa40587-21.html">planetary shrapnel</a>, having been blasted out of their parent star systems by catastrophic events, such as giant collisions between planetary objects. </p>
1507.  
1508. <p>Astronomers say that 'Oumuamua could have been <a href="https://science.nasa.gov/solar-system/comets/oumuamua/">travelling through the Milky Way</a> for hundreds of millions of years before its encounter with our solar system. Just two years after this unexpected visit, a second ISO – <a href="https://science.nasa.gov/solar-system/comets/2i-borisov/">the Borisov Comet</a> – was spotted, this time by an amateur astronomer in Crimea. These celestial interlopers have given us tantalising glimpses of material from far beyond our solar system. </p>
1509.  
1510. <p>But what if we could do more than just watch them fly by?</p>
1511.  
1512. <p>Studying ISOs up close would offer scientists the rare opportunity to learn more about far off star systems, which are too distant to send missions to. </p>
1513.  
1514. <p>There may be <a href="https://www.annualreviews.org/content/journals/10.1146/annurev-astro-071221-054221">over 10 septillion</a> (or ten with 24 zeros) ISOs in the Milky Way
1515. alone.  But if there are so many of them, why have we only seen two? Put simply, we cannot accurately predict when they will arrive. Large ISOs like 'Oumuamua, that are more easily detected, <a href="https://arxiv.org/abs/2502.03224">do not seem to visit</a> the solar system that often and they travel incredibly fast. </p>
1516.  
1517. <p>Ground- and space-based telescopes struggle to respond quickly to incoming ISOs, meaning that we are mostly looking at them <a href="https://www.astronomy.com/science/can-we-catch-oumuamua-interstellar-interloper/">after they pass through our cosmic neighbourhood</a>. However, innovative space missions could get us closer to objects like 'Oumuamua, by using breakthroughs in artificial intelligence (AI) to guide spacecraft safely to future visitors. Getting closer means we can get <a href="https://www.sciencedirect.com/science/article/pii/S003206332400014X">a better understanding</a> of their composition, geology, and activity – gaining insights into the conditions around other stars.</p>
1518.  
1519.  
1520.  
1521. <p>Emerging technologies being used to approach space debris could help to approach
1522. other unpredictable objects, transforming these fleeting encounters into profound
1523. scientific opportunities. So how do we get close? Speeding past Earth at an average of 32.14 km/s, ISOs give us less than a year for our spacecraft to try and intercept them <a href="https://www.astronomy.com/science/can-we-catch-oumuamua-interstellar-interloper/">after detection</a>. Catching up is not impossible – for example, it could be done via gravitational slingshot manoeuvres. However, it is difficult, costly and would take years to execute.</p>
1524.  
1525. <p>The good news is that the first wave of ISO-hunting missions is already in motion:
1526. Nasa’s mission concept <a href="https://www.sciencedirect.com/science/article/abs/pii/S0032063320303500">is called Bridge</a> and the European Space Agency (Esa) has a mission called <a href="https://link.springer.com/article/10.1007/s11214-023-01035-0">Comet Interceptor</a>. Once an incoming ISO is identified, Bridge would
1527. depart Earth to intercept it. However, launching from Earth currently requires a 30-day launch window after detection, which would cost valuable time.</p>
1528.  
1529. <figure class="align-center ">
1530.            <img alt="Comet interceptor mission" src="https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/661268/original/file-20250411-56-3s9g0l.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
1531.            <figcaption>
1532.              <span class="caption">The Comet Interceptor mission is scheduled to launch in 2029.</span>
1533.              <span class="attribution"><a class="source" href="https://www.esa.int/Science_Exploration/Space_Science/Comet_Interceptor/Top_five_questions_Comet_Interceptor_will_help_answer">ESA / Work performed by ATG under contract to ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
1534.            </figcaption>
1535.          </figure>
1536.  
1537. <p>Comet Interceptor is scheduled for launch in 2029 and comprises a larger spacecraft and two smaller robotic probes. Once launched, it will lie in wait a million miles from Earth, waiting to ambush a long period comet (slower comets that come from further away) – or potentially an ISO. Placing spacecraft in a “storage orbit” allows for rapid deployment when a suitable ISO is detected.</p>
1538.  
1539. <p>Another proposal from the Institute for Interstellar Studies, Project Lyra, <a href="https://i4is.org/what-we-do/technical/project-lyra/">assessed the feasibility</a> of chasing down 'Oumuamua, which has already sped far beyond Neptune’s orbit. They found that it would be <a href="https://www.sciencedirect.com/science/article/abs/pii/S0094576518317004">possible in theory</a> to catch up with the object, but that this would also be very technically challenging.</p>
1540.  
1541. <h2>The fast and the curious</h2>
1542.  
1543. <p>These missions are a start, but, as described, <a href="https://www.universetoday.com/articles/vera-rubin-observatory-should-find-5-interstellar-objects-a-year-many-of-which-we-could-chase-down-with-spacecraft">their biggest limitation</a> is speed. To chase down ISOs like 'Oumuamua, we’ll need to move a lot faster – and think smarter. </p>
1544.  
1545. <p>Future missions <a href="https://www.space.com/space-exploration/tech/this-spacecraft-swarm-could-spot-interstellar-visitors-zipping-through-our-solar-system">may rely</a> on cutting-edge AI and related fields such as <a href="https://www.ibm.com/think/topics/deep-learning">deep learning</a> – which seeks to emulate the decision making power of the human brain – to identify and respond to incoming objects in real time. Researchers are already testing small spacecraft that operate in coordinated “swarms”, allowing them to image targets from multiple angles and adapt mid-flight. </p>
1546.  
1547. <p>At the <a href="https://rubinobservatory.org/">Vera C Rubin Observatory</a> in Chile, a 10-year survey of the night sky is due to begin soon. This astronomical survey is expected to find dozens of ISOs each year. Simulations suggest we may be on the cusp of a detection boom. </p>
1548.  
1549. <p>Any spacecraft would need to reach high speeds once an object is spotted and
1550. ensure that its energy source doesn’t degrade, potentially after years waiting in
1551. “storage orbit”. A number of missions have already utilised a form of propulsion called a solar sail. </p>
1552.  
1553. <p>These use sunlight on the lightweight, reflective sail to push the spacecraft through space. This <a href="https://www.space.com/25800-ikaros-solar-sail.html">would dispense</a> with the need for heavy fuel tanks. The next generation of solar sail spacecraft <a href="https://www.universetoday.com/articles/laser-powered-sails-would-be-great-for-exploring-the-solar-system-too">could use lasers</a> on the sails to reach even higher speeds, which would offer a nimble and low cost solution compared to other futuristic fuels, such as nuclear propulsion. </p>
1554.  
1555. <figure class="align-center ">
1556.            <img alt="The Vera C. Rubin Observatory at dawn on Cerro Pachón in Chile." src="https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=290&fit=crop&dpr=1 600w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=290&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=290&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=365&fit=crop&dpr=1 754w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=365&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/661269/original/file-20250411-62-n2lfx3.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=365&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
1557.            <figcaption>
1558.              <span class="caption">The Vera Rubin Observatory in Chile should discover more interstellar objects.</span>
1559.              <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/rubin-Summit-Facility-at-Dawn/">RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/Y. AlSayyad</a></span>
1560.            </figcaption>
1561.          </figure>
1562.  
1563. <p>A spacecraft approaching an ISO will also need to withstand high temperatures and possibly erosion from dust being ejected from the object as it moves. While traditional shielding materials can protect spacecraft, they add weight and may slow them down. </p>
1564.  
1565. <p>To address this, researchers are exploring novel technologies for lightweight, more durable and resistant materials, such as advanced carbon fibres. Some could even be 3D printed. They are also looking at innovative uses of traditional materials such as cork and ceramics.</p>
1566.  
1567. <p>A suite of different approaches is needed that involve ground-based telescopes and space based missions, working together to anticipate, chase down and observe ISOs. </p>
1568.  
1569. <p><a href="https://www.rand.org/pubs/research_reports/RRA3121-1.html">New technology</a> could allow the spacecraft itself to identify and predict the trajectories of incoming objects. However, <a href="https://arstechnica.com/space/2025/04/trump-white-house-budget-proposal-eviscerates-science-funding-at-nasa/">potential cuts</a> to space science in the US, including to observatories like the <a href="https://www.space.com/space-exploration/james-webb-space-telescope/nasa-james-webb-space-telescope-faces-20-percent-budget-cuts">James Webb Space Telescope</a>, threaten such progress. </p>
1570.  
1571. <p>Emerging technologies must be embraced to make an approach and rendezvous with an ISO a real possibility. Otherwise, we will be left scrabbling, taking pictures from afar as yet another cosmic wanderer speeds away.</p><img src="https://counter.theconversation.com/content/254404/count.gif" alt="The Conversation" width="1" height="1" />
1572. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Billy Bryan works on projects at RAND Europe that are funded by the UK Space Agency and DG DEFIS. He is affiliated with RAND Europe&amp;#39;s Space Hub and is lead of the civil space theme, the University of Sussex Students&amp;#39; Union as a Trustee, and Rocket Science Ltd. as an advisor. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Chris Carter works on projects at RAND Europe that are funded by the UK Space Agency and DG DEFIS. He is affiliated with RAND Europe’s Space Hub and is a researcher in the civil space theme.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Theodora (Teddy) Ogden is a Senior Analyst at RAND Europe, where she works on defence and security issues in space. She was previously a fellow at Arizona State University, and before that was briefly at Nato.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1573.    <summary>Learning about these interstellar objects could give us insights into other star systems.</summary>
1574.    <author>
1575.      <name>Billy Bryan, Research Leader, RAND Europe</name>
1576.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/billy-bryan-300235"/>
1577.    </author>
1578.    <author>
1579.      <name>Chris Carter, Analyst, Science and Emerging Technology Team, RAND Europe</name>
1580.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/chris-carter-2371623"/>
1581.    </author>
1582.    <author>
1583.      <name>Theodora Ogden, Senior Analyst, Defence and Security Team, RAND Europe</name>
1584.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/theodora-ogden-1339970"/>
1585.    </author>
1586.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1587.  </entry>
1588.  <entry>
1589.    <id>tag:theconversation.com,2011:article/253546</id>
1590.    <published>2025-04-02T19:03:51Z</published>
1591.    <updated>2025-04-02T19:03:51Z</updated>
1592.    <link rel="alternate" type="text/html" href="https://theconversation.com/astronomers-listened-to-the-music-of-flickering-stars-and-discovered-an-unexpected-feature-253546"/>
1593.    <title>Astronomers listened to the ‘music’ of flickering stars – and discovered an unexpected feature</title>
1594.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/659189/original/file-20250402-56-zupvbf.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C338%2C5651%2C3172&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.shutterstock.com/image-illustration/3d-illustration-active-big-sun-1632652363"&gt;Pavel Gabzdyl / Shutterstock&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The “music” of starquakes – enormous vibrations caused by bursting bubbles of gas that ripple throughout the bodies of many stars – can reveal far more information about the stars’ histories and inner workings than scientists thought.&lt;/p&gt;
1595.  
1596. <p>In <a href="https://www.nature.com/articles/s41586-025-08760-2">new research published in Nature</a>, we analysed the frequency signatures of starquakes across a broad range of giant stars in the M67 star cluster, almost 3,000 light years from Earth. </p>
1597.  
1598. <p>Using observations from the Kepler space telescope’s K2 mission, we had a rare opportunity to track the evolution of stars during most of their journey through the giant phase of the stellar life cycle.</p>
1599.  
1600. <p>In doing so, we discovered that these stars get stuck “playing the same part of their tune” once their turbulent outer layer reaches a sensitive region deep inside.</p>
1601.  
1602. <p>This discovery reveals a new way to understand the history of stars – and of the entire galaxy.</p>
1603.  
1604. <h2>The sound of starquakes</h2>
1605.  
1606. <p>Starquakes happen in most stars (like our Sun) that have a bubbling outer layer, like a pot of boiling water. Bubbles of hot gas rise and burst at the surface, sending ripples through the entire star that cause it to vibrate in particular ways.</p>
1607.  
1608. <p>We can detect these vibrations, which occur at specific “resonant frequencies”, by looking for subtle variations in the brightness of the star. By studying the frequencies of each star in a group called a cluster, we can tune into the cluster’s unique “song”. </p>
1609.  
1610. <p>Our study challenges previous assumptions about resonant frequencies in giant stars, revealing they offer deeper insights into stellar interiors than previously thought. Moreover, our study has opened new ways to decipher the history of our Galaxy.</p>
1611.  
1612. <h2>The melody of a stellar cluster</h2>
1613.  
1614. <p>Astronomers have long sought to understand how stars like our Sun evolve over time. </p>
1615.  
1616. <p>One of the best ways to do this is by studying clusters – groups of stars that formed together and share the same age and composition. A cluster called M67 has attracted a lot of attention because it contains many stars with a similar chemical makeup to the Sun.</p>
1617.  
1618. <p>Just as earthquakes help us study Earth’s interior, starquakes reveal what lies beneath a star’s surface. Each star “sings” a melody, with frequencies determined by its internal structure and physical properties.</p>
1619.  
1620. <p>Larger stars produce deeper, slower vibrations, while smaller stars vibrate at higher pitches. And no star plays just one note – each one resonates with a full spectrum of sound from its interior.</p>
1621.  
1622. <h2>A surprising signature</h2>
1623.  
1624. <p>Among the key frequency signatures is the so-called small spacing – a group of resonant frequencies quite close together. In younger stars, such as the Sun, this signature can provide clues about how much hydrogen the star still has left to burn in its core.</p>
1625.  
1626. <p>In red giants the situation is different. These older stars have used up all the hydrogen in their cores, which are now inert. </p>
1627.  
1628. <p>However, hydrogen fusion continues in a shell surrounding the core. It was long assumed that the small spacings in such stars offered little new information.</p>
1629.  
1630. <h2>A stalled note</h2>
1631.  
1632. <p>When we measured the small spacings of stars in M67, we were surprised to see they revealed changes in the star’s internal fusion regions. </p>
1633.  
1634. <p>As the hydrogen-burning shell thickened, the spacings increased. When the shell moved inward, they shrank.</p>
1635.  
1636. <p>Then we found something else unexpected: at a certain stage, the small spacings stalled. It was like a record skipping on a note.</p>
1637.  
1638. <figure>
1639.            <iframe width="440" height="260" src="https://www.youtube.com/embed/loxmLI0iAgg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1640.            
1641.          </figure>
1642.  
1643. <p>We discovered that this stalling appears during a specific stage in the life of a giant star — when its outer envelope, the “boiling” layer that transports heat, grows so deep that it makes up about 80% of the star’s mass. At this point the inner boundary of the envelope reaches into a highly sensitive region of the star. </p>
1644.  
1645. <p>This boundary is extremely turbulent, and the speed of sound shifts steeply across it — and that steep change affects how sound waves travel through the star. We also found that the stalling frequency is distinctively determined by the star’s mass and chemical composition.</p>
1646.  
1647. <p>This gives us a new way to identify stars in this phase and estimate their ages with improved precision.</p>
1648.  
1649. <h2>The history of the galaxy</h2>
1650.  
1651. <p>Stars are like fossil records. They carry the imprint of the environments in which they formed, and studying them lets us piece together the story of our galaxy.</p>
1652.  
1653. <p>The Milky Way has grown by merging with smaller galaxies, forming stars at different times in different regions. Better age estimates across the galaxy help us reconstruct this history in greater detail.</p>
1654.  
1655. <p>Clusters like M67 also provide a glimpse into the future of our own Sun, offering insight into the changes it will experience over billions of years.</p>
1656.  
1657. <p>This discovery gives us a new tool – and a new reason to revisit data we already have. With years of seismic observations from across the Milky Way, we can now return to those stars and “listen” again, this time knowing what to listen for.</p><img src="https://counter.theconversation.com/content/253546/count.gif" alt="The Conversation" width="1" height="1" />
1658. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Claudia Reyes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1659.    <summary>Stars are constantly vibrating because of ‘starquakes’. Listening to their sound can reveal a surprising amount of information.</summary>
1660.    <author>
1661.      <name>Claudia Reyes, Postdoctoral Fellow, Research School of Astronomy &amp; Astrophysics, Australian National University</name>
1662.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/claudia-reyes-2359825"/>
1663.    </author>
1664.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1665.  </entry>
1666.  <entry>
1667.    <id>tag:theconversation.com,2011:article/251560</id>
1668.    <published>2025-03-31T12:15:10Z</published>
1669.    <updated>2025-03-31T12:15:10Z</updated>
1670.    <link rel="alternate" type="text/html" href="https://theconversation.com/jets-from-powerful-black-holes-can-point-astronomers-toward-where-and-where-not-to-look-for-life-in-the-universe-251560"/>
1671.    <title>Jets from powerful black holes can point astronomers toward where − and where not − to look for life in the universe</title>
1672.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/656716/original/file-20250320-56-5esaam.jpg?ixlib=rb-4.1.0&amp;amp;rect=0%2C0%2C1596%2C1062&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Black holes, like the one in this illustration, can spray powerful jets.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_the_black_hole_in_the_M87_galaxy_and_its_powerful_jet_%28eso2305b%29.jpg"&gt;S. Dagnello (NRAO/AUI/NSF)&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;One of the most powerful objects in the universe is a &lt;a href="https://public.nrao.edu/radio-astronomy/quasars/"&gt;radio quasar&lt;/a&gt; – a spinning black hole spraying out highly energetic particles. Come too close to one, and you’d get sucked in by its gravitational pull, or burn up from the intense heat surrounding it. But ironically, studying black holes and their jets can give researchers insight into where potentially habitable worlds might be in the universe.&lt;/p&gt;
1673.  
1674. <p><a href="https://scholar.google.com/citations?user=4YxMlZUAAAAJ&hl=en">As an astrophysicist</a>, I’ve spent two decades modeling how black holes spin, how that creates jets, and how they affect the environment of space around them.</p>
1675.  
1676. <h2>What are black holes?</h2>
1677.  
1678. <p><a href="https://theconversation.com/the-scariest-things-in-the-universe-are-black-holes-and-here-are-3-reasons-148615">Black holes</a> are massive, astrophysical objects that use gravity to pull surrounding objects into them. Active black holes have a pancake-shaped structure around them called an <a href="https://science.nasa.gov/universe/black-holes/anatomy/">accretion disk</a>, which contains hot, electrically charged gas.</p>
1679.  
1680. <p>The plasma that makes up the accretion disk comes from farther out in the galaxy. When <a href="https://www.reuters.com/science/nasa-releases-webb-telescope-images-galactic-merger-2024-07-12/">two galaxies collide and merge</a>, gas is funneled into the central region of that merger. Some of that gas ends up getting close to the newly merged black hole and forms the accretion disk.</p>
1681.  
1682. <p>There is one <a href="https://theconversation.com/supermassive-black-holes-have-masses-of-more-than-a-million-suns-but-their-growth-has-slowed-as-the-universe-has-aged-233396">supermassive black hole</a> <a href="https://theconversation.com/powerful-black-holes-might-grow-up-in-bustling-galactic-neighborhoods-211326">at the heart</a> of every massive galaxy. </p>
1683.  
1684. <p>Black holes and their disks <a href="https://www.astronomy.com/science/what-is-black-hole-spin/">can rotate</a>, and when they do, they drag space and time with them – a concept that’s mind-boggling and very hard to grasp conceptually. But black holes are important to study because they produce enormous amounts of energy that can influence galaxies.</p>
1685.  
1686. <p>How energetic a black hole is depends on different factors, such as the mass of the black hole, whether it rotates rapidly, and whether lots of material falls onto it. Mergers fuel the most energetic black holes, but not all black holes are fed by gas from a merger. In <a href="https://esahubble.org/wordbank/spiral-galaxy/">spiral galaxies</a>, for example, less gas tends to fall into the center, and the central black hole tends to have less energy. </p>
1687.  
1688. <p>One of the ways they generate energy is through what scientists call “<a href="https://theconversation.com/astronomers-have-detected-one-of-the-biggest-black-hole-jets-in-the-sky-188357">jets” of highly energetic particles</a>. A black hole can pull in magnetic fields and energetic particles surrounding it, and then as the black hole rotates, the magnetic fields twist into a jet that sprays out highly energetic particles. </p>
1689.  
1690. <p>Magnetic fields twist around the black hole as it rotates to store energy – kind of like when you pull and twist a rubber band.  When you release the rubber band, it snaps forward. Similarly, the magnetic fields release their energy by producing these jets.</p>
1691.  
1692. <figure class="align-center zoomable">
1693.            <a href="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing an accretion disk and black hole spraying out a jet of particles, surrounded by magnetic field lines." src="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656718/original/file-20250320-74-qcfffi.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1694.            <figcaption>
1695.              <span class="caption">The accretion disk around a black hole can form a jet of hot, energetic particles surrounded by magnetic field lines.</span>
1696.              <span class="attribution"><a class="source" href="https://esahubble.org/images/opo1332b/">NASA, ESA, and A. Feild (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
1697.            </figcaption>
1698.          </figure>
1699.  
1700. <p>These jets can speed up or suppress the formation of stars in a galaxy, depending on how the energy is released into the black hole’s host galaxy.</p>
1701.  
1702. <h2>Rotating black holes</h2>
1703.  
1704. <p>Some black holes, however, rotate in a different direction than the accretion disk around them. This phenomenon is called counterrotation, and some <a href="https://doi.org/10.3390/galaxies11030066">studies my colleagues and I have conducted</a> suggest that it’s a key feature governing the behavior of one of the most powerful kinds of objects in the universe: the radio quasar. </p>
1705.  
1706. <p>Radio quasars are the subclass of black holes that produce the <a href="https://esahubble.org/wordbank/quasar/">most powerful energy and jets</a>. </p>
1707.  
1708. <p>You can imagine the black hole as a rotating sphere, and the accretion disk as a disk with a hole in the center. The black hole sits in that center hole and rotates one way, while the accretion disk rotates the other way. </p>
1709.  
1710. <p>This counterrotation forces the black hole to spin down and eventually up again in the other direction, called corotation. Imagine a basketball that spins one way, but you keep tapping it to rotate in the other. The tapping will spin the basketball down. If you continue to tap in the opposite direction, it will eventually spin up and rotate in the other direction. The accretion disk does the same thing.</p>
1711.  
1712. <p>Since the jets tap into the black hole’s rotational energy, they are powerful only when the black hole is spinning rapidly. The change from counterrotation to corotation takes at least 100 million years. Many initially counterrotating black holes take billions of years to become rapidly spinning corotating black holes.</p>
1713.  
1714. <p>So, these black holes would produce powerful jets both early and later in their lifetimes, with an interlude in the middle where the jets are either weak or nonexistent. </p>
1715.  
1716. <p>When the black hole spins in counterrotation with respect to its accretion disk, that motion produces strong jets that push molecules in the surrounding gas close together, <a href="https://doi.org/10.1088/1538-3873/ac8f70">which leads to</a> the <a href="https://www.cfa.harvard.edu/research/topic/star-formation">formation of stars</a>.</p>
1717.  
1718. <p>But later, in corotation, the jet tilts. This tilt makes it so that the jet impinges directly on the gas, heating it up and inhibiting star formation. In addition to that, the jet also <a href="https://theconversation.com/im-an-astrophysicist-mapping-the-universe-with-data-from-the-chandra-x-ray-observatory-clear-sharp-photos-help-me-study-energetic-black-holes-229668">sprays X-rays</a> across the galaxy. <a href="https://imagine.gsfc.nasa.gov/science/toolbox/xray_astronomy1.html">Cosmic X-rays</a> are bad for life because they can harm organic tissue. </p>
1719.  
1720. <p>For life to thrive, it most likely needs a planet with <a href="https://science.nasa.gov/exoplanets/habitable-zone/">a habitable ecosystem</a>, and clouds of hot gas saturated with X-rays don’t contain such planets. So, astronomers can instead look for galaxies without a tilted jet coming from its black hole. This idea is key to understanding where intelligence could potentially have emerged and matured in the universe. </p>
1721.  
1722. <h2>Black holes as a guide</h2>
1723.  
1724. <p>By early 2022, I had built <a href="https://doi.org/10.3390/galaxies11030066">a black hole model</a> to use as a guide. It could point out environments with the right kind of black holes to produce the greatest number of planets without spraying them with X-rays. Life in such environments could emerge to its full potential. </p>
1725.  
1726. <figure>
1727.            <iframe width="440" height="260" src="https://www.youtube.com/embed/b7mTVX9IE0s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1728.            <figcaption><span class="caption">Looking at black holes and their role in star formation could help scientists predict when and where life was most likely to form.</span></figcaption>
1729.          </figure>
1730.  
1731. <p>Where are such conditions present? The answer is low-density environments where galaxies had merged about 11 billion years ago.</p>
1732.  
1733. <p>These environments had black holes whose powerful jets enhanced the rate of star formation, but they never experienced a bout of tilted jets in corotation. In short, <a href="https://doi.org/10.3390/galaxies11030066">my model suggested</a> that theoretically, the most advanced extraterrestrial civilization would have likely emerged on the cosmic scene <a href="https://phys.org/news/2023-05-advanced-life-peaked-billions-years.html">far away and billions of years ago</a>.</p><img src="https://counter.theconversation.com/content/251560/count.gif" alt="The Conversation" width="1" height="1" />
1734. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;David Garofalo does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1735.    <summary>Whether a galactic environment has the right conditions for habitable planets to form could depend on how the black hole in that galaxy is rotating.</summary>
1736.    <author>
1737.      <name>David Garofalo, Professor of Physics, Kennesaw State University</name>
1738.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/david-garofalo-2324507"/>
1739.    </author>
1740.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1741.  </entry>
1742.  <entry>
1743.    <id>tag:theconversation.com,2011:article/253343</id>
1744.    <published>2025-03-31T03:19:40Z</published>
1745.    <updated>2025-03-31T03:19:40Z</updated>
1746.    <link rel="alternate" type="text/html" href="https://theconversation.com/the-best-space-telescope-you-never-heard-of-just-shut-down-253343"/>
1747.    <title>The best space telescope you never heard of just shut down</title>
1748.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/658592/original/file-20250331-56-6zm1s8.jpg?ixlib=rb-4.1.0&amp;amp;rect=904%2C0%2C4337%2C2436&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_creates_richest_star_map_of_our_Galaxy_and_beyond"&gt;ESA / Gaia / DPAC&lt;/a&gt;, &lt;a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/"&gt;CC BY-SA&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;On Thursday 27 March, the European Space Agency &lt;a href="https://www.esa.int/"&gt;(ESA)&lt;/a&gt; sent its last messages to the &lt;a href="https://www.esa.int/Science_Exploration/Space_Science/Gaia"&gt;Gaia Spacecraft&lt;/a&gt;. They told Gaia to &lt;a href="https://www.esa.int/Enabling_Support/Operations/Farewell_Gaia!_Spacecraft_operations_come_to_an_end"&gt;shut down its communication systems and central computer&lt;/a&gt; and said goodbye to this amazing space telescope. &lt;/p&gt;
1749.  
1750. <p>Gaia has been the most successful ESA space mission ever, so why did they turn Gaia off? What did Gaia achieve? And perhaps most importantly, why was it my favourite space telescope?</p>
1751.  
1752.  
1753.  
1754. <h2>Running on empty</h2>
1755.  
1756. <p>Gaia was retired for a simple reason: after more than 11 years in space, it <a href="https://www.cosmos.esa.int/web/gaia/end-of-observations">ran out of the cold gas propellant</a> it needed to keep scanning the sky. </p>
1757.  
1758. <p>The telescope did its last observation on 15 January 2025. The ESA team then performed testing for a few weeks, before telling Gaia to leave its home at <a href="https://www.esa.int/Science_Exploration/Space_Science/Gaia_overview#:%7E:text=Gaia%20is%20mapping%20the%20stars,as%20we%20orbit%20the%20Sun">a point in space called L2</a> and start orbiting the Sun away from Earth.</p>
1759.  
1760. <p>L2 is one of five “Lagrangian points” around Earth and the Sun where gravitational conditions make for a nice, stable orbit. L2 is located 1.5 million kilometres from Earth on the “dark side”, opposite the Sun. </p>
1761.  
1762.  
1763.  
1764. <p>L2 is <a href="https://science.nasa.gov/solar-system/resources/faq/what-are-lagrange-points/">a highly prized location</a> because it’s a stable spot to orbit, it’s close enough to Earth for easy communication, and spacecraft can use the Sun behind them for solar power while looking away from the Sun out into space. </p>
1765.  
1766. <p>It’s also too far away from Earth to send anyone on a repair mission, so once your spacecraft gets there it’s on its own.</p>
1767.  
1768. <h2>Keeping L2 clear</h2>
1769.  
1770. <p>L2 currently hosts the <a href="https://science.nasa.gov/mission/webb/">James Webb Space Telescope</a> (operated by the USA, Europe and Canada), the European <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid">Euclid mission</a>, the Chinese <a href="https://spacenews.com/change-6-orbiter-turns-up-at-sun-earth-lagrange-point-after-moon-sampling-mission/">Chang’e 6 orbiter</a> and the <a href="https://www.eoportal.org/satellite-missions/spektrg-srg#background">joint Russian-German Spektr-RG</a> observatory. Since L2 is such a key location for space missions, it’s essential to keep it clear of debris and retired spacecraft.</p>
1771.  
1772. <figure class="align-center zoomable">
1773.            <a href="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="'Bye' appears in the status of Gaia's subsystems as the spacecraft is powered down and switched off for the final time" src="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/658600/original/file-20250331-56-9rh9cc.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1774.            <figcaption>
1775.              <span class="caption">A final status update from Gaia.</span>
1776.              <span class="attribution"><a class="source" href="https://bsky.app/profile/operations.esa.int/post/3lldwldhjsk2n">ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
1777.            </figcaption>
1778.          </figure>
1779.  
1780. <p>Gaia used its thrusters for the last time to push itself away from L2, and is now drifting around the Sun in a “retirement orbit” where it won’t get in anybody’s way. </p>
1781.  
1782. <p>As part of the retirement process, the Gaia team <a href="https://bsky.app/profile/operations.esa.int/post/3lldvduwgts2i">wrote farewell messages into the craft’s software</a> and sent it the names of around 1,500 people who worked on Gaia over the years.</p>
1783.  
1784. <h2>What is Gaia?</h2>
1785.  
1786. <p>Gaia looks a bit like a spinning top hat in space. Its main mission was to produce a detailed, <a href="https://astrobiology.nasa.gov/missions/gaia-space-observatory/#:%7E:text=Mission%20Overview,and%20evolution%20of%20the%20Galaxy.">three-dimensional map of our galaxy, the Milky Way</a>. </p>
1787.  
1788. <p>To do this, it measured the precise positions and motions of <a href="https://www.cosmos.esa.int/web/gaia/dr3">1.46 billion objects in space</a>. Gaia also measured brightnesses and variability and those data were used to provide temperatures, gravitational parameters, stellar types and more for millions of stars. One of the key pieces of information Gaia provided was the distance to millions of stars.</p>
1789.  
1790.  
1791.  
1792. <h2>A cosmic measuring tape</h2>
1793.  
1794. <p>I’m a radio astronomer, which means I use radio telescopes here on Earth to explore the Universe. Radio light is the longest wavelength of light, invisible to human eyes, and I use it to investigate magnetic stars. </p>
1795.  
1796. <p>But even though I’m a radio astronomer and Gaia was an optical telescope, looking at the same wavelengths of light our eyes can see, I use Gaia data almost every single day. </p>
1797.  
1798. <p>I used it today to find out how far away, how bright, and how fast a star was. Before Gaia, I would probably never have known how far away that star was. </p>
1799.  
1800. <p>This is essential for figuring out how bright <a href="https://ui.adsabs.harvard.edu/abs/2024PASA...41...84D/abstract">the stars I study</a> really are, which helps me understand the physics of what’s happening in and around them.</p>
1801.  
1802.  
1803.  
1804. <h2>A huge success</h2>
1805.  
1806. <p>Gaia has contributed to thousands of articles in astronomy journals. Papers released by the Gaia collaboration have been cited <a href="https://ui.adsabs.harvard.edu/search/q=docs(library%2Fgwvt3P9gSCSLw7rMseAE2w)&sort=citation_count%20desc%2C%20bibcode%20desc&p_=0">well over 20,000 times in total</a>.</p>
1807.  
1808. <p>Gaia has produced too many science results to share here. To take just one example, Gaia <a href="https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_Milky_Way_map_by_Gaia">improved our understanding of the structure of our own galaxy</a> by showing that it has multiple spiral arms that are less sharply defined than we previously thought.</p>
1809.  
1810.  
1811.  
1812. <h2>Not really the end for Gaia</h2>
1813.  
1814. <p>It’s difficult to express how revolutionary Gaia has been for astronomy, but we can let the numbers speak for themselves. Around five astronomy journal articles are published every day that use Gaia data, making Gaia <a href="https://phys.org/news/2025-02-mission-space-telescope-gaia.html">the most successful ESA mission ever</a>. And that won’t come to a complete stop when Gaia retires.</p>
1815.  
1816. <p>The Gaia collaboration has published three data releases so far. This is where the collaboration performs the processing and checks on the data, adds some important analysis and releases all of that in one big hit. </p>
1817.  
1818. <p>And luckily, there are <a href="https://www.cosmos.esa.int/web/gaia/release">two more big data releases</a> with even more information to come. The fourth data release is expected in mid to late 2026. The fifth and final data release, containing all of the Gaia data from the whole mission, will come out sometime in the 2030s.</p>
1819.  
1820. <p>This article is my own small tribute to a telescope that changed astronomy as we know it. So I will end by saying a huge thank you to everyone who has ever worked on this amazing space mission, whether it was engineering and operations, turning the data into the amazing resource it is, or any of the other many jobs that make a mission successful. And thank you to those who continue to work on the data as we speak. </p>
1821.  
1822. <p>Finally, thank you to my favourite space telescope. Goodbye, Gaia, I’ll miss you.</p><img src="https://counter.theconversation.com/content/253343/count.gif" alt="The Conversation" width="1" height="1" />
1823. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Laura Nicole Driessen is an ambassador for the Orbit Centre of Imagination at the Rise and Shine Kindergarten, in Sydney&amp;#39;s Inner West.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1824.    <summary>An astronomer says goodbye to Gaia, the satellite that mapped the galaxy.</summary>
1825.    <author>
1826.      <name>Laura Nicole Driessen, Postdoctoral Researcher in Radio Astronomy, University of Sydney</name>
1827.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/laura-nicole-driessen-892965"/>
1828.    </author>
1829.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1830.  </entry>
1831.  <entry>
1832.    <id>tag:theconversation.com,2011:article/252627</id>
1833.    <published>2025-03-20T03:46:50Z</published>
1834.    <updated>2025-03-20T03:46:50Z</updated>
1835.    <link rel="alternate" type="text/html" href="https://theconversation.com/cosmic-dark-energy-may-be-weakening-astronomers-say-raising-questions-about-the-fate-of-the-universe-252627"/>
1836.    <title>Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe</title>
1837.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/656444/original/file-20250319-56-8gcr0a.jpeg?ixlib=rb-4.1.0&amp;amp;rect=0%2C5%2C3600%2C2387&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;KPNO / NOIRLab / NSF / AURAB / Tafreshi&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;The universe has been expanding ever since the Big Bang almost 14 billion years ago, and astronomers believe a kind of invisible force called dark energy is making it accelerate faster.&lt;/p&gt;
1838.  
1839. <p>However, <a href="https://data.desi.lbl.gov/doc/papers">new results</a> from the <a href="https://www.desi.lbl.gov/">Dark Energy Spectroscopic Instrument</a> (DESI), released today, suggest dark energy may be changing over time. </p>
1840.  
1841. <p>If the result is confirmed, it may overturn our current theories of cosmology – and have significant consequences for the eventual fate of the universe. In extreme scenarios, evolving dark energy could either accelerate the universe’s expansion to the point of tearing it apart in a “Big Rip” or cause it to collapse inward in a “Big Crunch”. </p>
1842.  
1843. <p>As a member of the DESI collaboration, which includes more than 900 researchers from 70 institutions worldwide, I have been involved in the analysis and interpretation of the dark energy results.</p>
1844.  
1845. <h2>A new picture of dark energy</h2>
1846.  
1847. <p><a href="https://iopscience.iop.org/article/10.1086/300499">First discovered in 1998</a>, dark energy is a kind of essence that seems to permeate space and make the universe expand at an ever-increasing rate. Cosmologists have generally assumed it is constant: it was the same in the past as it will be in the future.</p>
1848.  
1849. <p>The assumption of constant dark energy is baked into the widely accepted Lambda-CDM model of the universe. In this model, only 5% of the universe is made up of the ordinary matter we can see. Another 25% is invisible dark matter than can only be detected indirectly. And by far the bulk of the universe – a whopping 70% – is dark energy.</p>
1850.  
1851. <p>DESI’s results are not the only thing that gives us clues about dark energy. We can also look at evidence from a kind of exploding stars called Type Ia supernovae, and the way the path of light is warped as it travels through the universe (so-called weak gravitational lensing). </p>
1852.  
1853. <p>Measurements of the faint afterglow of the Big Bang (known as the cosmic microwave background) are also important. They do not directly measure dark energy or how it evolves, but they provide clues about the universe’s structure and energy content — helping to test dark energy models when combined with other data. </p>
1854.  
1855. <figure class="align-center zoomable">
1856.            <a href="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Oval image in splotches of blue, yellow and green." src="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656511/original/file-20250320-56-di81x6.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1857.            <figcaption>
1858.              <span class="caption">The cosmic microwave background – the afterglow of the Big Bang – contains clues about the nature of dark energy.</span>
1859.              <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cosmic_microwave_background#/media/File:WMAP_2012.png">WMAP / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
1860.            </figcaption>
1861.          </figure>
1862.  
1863. <p>When the new DESI results are combined with all this cosmological data, we see hints that dark energy is more complicated than we thought. </p>
1864.  
1865. <p>It seems dark energy may have been stronger in the past and is now weakening. This result challenges the foundation of the Lambda-CDM model, and would have profound implications for the future of the universe. </p>
1866.  
1867. <h2>How DESI maps the universe</h2>
1868.  
1869. <p>The DESI project is based at the Kitt Peak National Observatory in Arizona. Its goal is to create the most extensive 3D map of the universe ever made. </p>
1870.  
1871. <p>To do this, it uses a powerful spectroscope to precisely measure the frequency of light coming from up to 5,000 distant galaxies at once. This lets astronomers determine how far away the galaxies are, and how fast they are moving.</p>
1872.  
1873. <p>By mapping galaxies, we can detect subtle patterns in their large-scale distribution called baryon acoustic oscillations. These patterns can be used as cosmic rulers to measure the history of the universe’s expansion. </p>
1874.  
1875. <figure class="align-center zoomable">
1876.            <a href="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large telescope with some kind of large black instrument attached to it." src="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/656507/original/file-20250320-62-de756b.jpeg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1877.            <figcaption>
1878.              <span class="caption">The Dark Energy Spectroscopic Instrument can analysed the frequency of light from up to 5,000 distant galaxies at a time.</span>
1879.              <span class="attribution"><span class="source">Marilyn Sargent / Berkeley Lab</span></span>
1880.            </figcaption>
1881.          </figure>
1882.  
1883. <p>By tracking these patterns over time, DESI can map how the universe’s expansion rate has changed.</p>
1884.  
1885. <p>DESI is only halfway through a planned five-year survey of the universe, releasing data in batches as it goes. </p>
1886.  
1887. <p>The new results are based on the second batch of data, which includes measurements from more than 14 million galaxies and brightly glowing galactic cores called quasars. This dataset spans a cosmic time window of 11 billion years — from when the universe was just 2.8 billion years old to the present day.</p>
1888.  
1889. <h2>New data, new challenges</h2>
1890.  
1891. <p>The new DESI results represent a major step forward compared with what we saw in the first batch of data. The amount of data collected has more than doubled, which has improved the accuracy of the measurements and made the findings more reliable.</p>
1892.  
1893. <p>Results from the first batch of data gave a hint that dark energy might not behave like a simple cosmological constant — but it wasn’t strong enough to draw firm conclusions. Now, the second batch of data has made this evidence stronger.</p>
1894.  
1895. <p>The strength of the results depends on which other datasets it is combined with, particularly the type of supernova data included. However, no combination of data so far meets the typical “five sigma” statistical threshold physicists use as the marker of a confirmed new discovery.</p>
1896.  
1897. <h2>The fate of the universe</h2>
1898.  
1899. <p>Still, the fact this pattern is becoming clearer with more data suggests that something deeper might be going on. If there is no error in the data or the analysis, this could mean our understanding of dark energy – and perhaps the entire standard model of cosmology – needs to be revised.</p>
1900.  
1901. <p>If dark energy is changing over time, it could have profound implications for the ultimate fate of the universe. </p>
1902.  
1903. <p>If dark energy grows stronger over time, the universe could face a “Big Rip” scenario, where galaxies, stars, and even atoms are torn apart by the increasing expansion rate. If dark energy weakens or reverses, the expansion could eventually slow down or even reverse, leading to a “Big Crunch”.</p>
1904.  
1905. <h2>What’s next?</h2>
1906.  
1907. <p>DESI aims to collect data from a total of 40 million galaxies and quasars. The additional data will improve statistical precision and help refine the dark energy model even further.</p>
1908.  
1909. <p>Future DESI releases and independent cosmological experiments will be crucial in determining whether this represents a fundamental shift in our understanding of the universe.</p>
1910.  
1911. <p>Future data could confirm whether dark energy is indeed evolving – or whether the current hints are just a statistical anomaly. If dark energy is found to be dynamic, it could require new physics beyond Einstein’s theory of general relativity and open the door to new models of particle physics and quantum gravity.</p>
1912.  
1913. <figure>
1914.            <iframe width="440" height="260" src="https://www.youtube.com/embed/fQkFS5yot5I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
1915.            
1916.          </figure><img src="https://counter.theconversation.com/content/252627/count.gif" alt="The Conversation" width="1" height="1" />
1917. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Rossana Ruggeri is part of the DESI Collaboration.  She receives funding from her ARC DECRA grant. She is affiliated with QUT and UQ. &lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
1918.    <summary>A project to map galaxies across the universe may have spied cracks in the foundation of our understanding of the cosmos.</summary>
1919.    <author>
1920.      <name>Rossana Ruggeri, Lecturer and ARC DECRA Fellow, Queensland University of Technology</name>
1921.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/rossana-ruggeri-1432957"/>
1922.    </author>
1923.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
1924.  </entry>
1925.  <entry>
1926.    <id>tag:theconversation.com,2011:article/252382</id>
1927.    <published>2025-03-17T19:10:48Z</published>
1928.    <updated>2025-03-17T19:10:48Z</updated>
1929.    <link rel="alternate" type="text/html" href="https://theconversation.com/less-than-1-of-the-worlds-biggest-radio-telescope-is-complete-but-its-first-image-reveals-a-sky-dotted-with-ancient-galaxies-252382"/>
1930.    <title>Less than 1% of the world’s biggest radio telescope is complete – but its first image reveals a sky dotted with ancient galaxies</title>
1931.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&amp;amp;rect=42%2C649%2C2284%2C1390&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The first image from an early working version of the SKA-Low telescope, showing around 85 galaxies.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;SKAO&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Part of the world’s biggest mega-science facility – the &lt;a href="https://www.skao.int/en"&gt;SKA Observatory&lt;/a&gt; – is being built in outback Western Australia. &lt;/p&gt;
1932.  
1933. <p>After decades of planning, countless hours of work, and more than a few setbacks, an early working version of the telescope has captured its first glimpse of the sky.</p>
1934.  
1935. <p>Using 1,024 of what will eventually be 131,072 radio antennas, the first <a href="https://www.skao.int/en/explore/telescopes/ska-low">SKA-Low</a> image shows a tiny sliver of sky dotted with ancient galaxies billions of light-years from Earth.</p>
1936.  
1937. <p>This first snapshot shows the system works, and will improve dramatically in the coming months and years – and starts a new chapter in our exploration of the universe. </p>
1938.  
1939. <h2>A glimpse of the universe</h2>
1940.  
1941. <p>The SKA-Low telescope is currently under construction on Wajarri Yamaji Country in Western Australia, around 600 kilometres north of Perth. Together with the SKA-Mid telescope (under construction in South Africa), the two telescopes will make up the world’s largest and most sensitive radio observatory.</p>
1942.  
1943. <p>SKA-Low will consist of thousands of antennas spread across a vast area. It is designed to detect low-frequency radio signals from some of the most distant and ancient objects in the universe.</p>
1944.  
1945. <p>The first image, made using just 1,024 of the planned 131,000 antennas, is remarkably clear, confirming that the complex systems for transmitting and processing data from the antennas are working properly. Now we can move on to more detailed observations to analyse and verify the telescope’s scientific output.</p>
1946.  
1947. <h2>Bright galaxies, billions of years old</h2>
1948.  
1949. <p>The image shows a patch of the sky, approximately 25 square degrees in area, as seen in radio waves.</p>
1950.  
1951. <p>Twenty-five square degrees is an area of sky that would fit 100 full Moons. For comparison, it would be about the area of sky that a small apple would cover if you held it at arm’s length.</p>
1952.  
1953. <figure class="align-center zoomable">
1954.            <a href="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&rect=42%2C649%2C2284%2C1390&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing dots of white on a black background." src="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&rect=42%2C649%2C2284%2C1390&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655550/original/file-20250317-68-uad278.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1955.            <figcaption>
1956.              <span class="caption">The first image from an early working version of the SKA-Low telescope, showing around 85 galaxies.</span>
1957.              <span class="attribution"><span class="source">SKAO</span></span>
1958.            </figcaption>
1959.          </figure>
1960.  
1961. <p>The dots in the image look like stars, but are actually some of the brightest galaxies in the universe. These galaxies are billions of light-years away, so the galaxies we are seeing now were emitting this light when the universe was half its current age.</p>
1962.  
1963. <p>They are so bright because each of these distant galaxies contains a supermassive black hole. Gas orbiting around black holes is very hot and moves very quickly, emitting energy in X-rays and radio waves. SKA-Low can detect these radio waves that have travelled billions of light years across the universe to reach Earth.</p>
1964.  
1965. <h2>The world’s largest radio telescope</h2>
1966.  
1967. <p>SKA-Low and SKA-Mid are both being built by the SKAO, a global project to build cutting-edge telescopes that will revolutionise our understanding of the universe and deliver benefits to society. (SKA stands for “square kilometre array”, describing the initial estimated collecting area of all the antennas and radio dishes put together.)</p>
1968.  
1969. <p>My own involvement in the project began in 2014. Since then I, along with many local and international colleagues, have deployed and verified several prototype systems on the path to SKA-Low. To now be part of the team that is making the first images with the rapidly growing telescope is extremely satisfying.</p>
1970.  
1971. <h2>A complex system with no moving parts</h2>
1972.  
1973. <p>SKA-Low will be made up of 512 aperture arrays (or stations), each comprised of 256 antennas. </p>
1974.  
1975. <p>Unlike traditional telescopes, aperture arrays have no moving parts, which makes them easier to maintain. The individual antennas receive signals from all directions at once and – to produce images – we use complex mathematics to combine the signals from each individual antenna and “steer” the telescope. </p>
1976.  
1977. <figure class="align-center zoomable">
1978.            <a href="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of many Christmas-tree like antennas in an open field." src="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655560/original/file-20250317-56-fw31ny.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1979.            <figcaption>
1980.              <span class="caption">The SKA-Low telescope uses arrays of radio antennas (called stations) to create images of the universe.</span>
1981.              <span class="attribution"><span class="source">SKAO / Max Alexander</span></span>
1982.            </figcaption>
1983.          </figure>
1984.  
1985. <p>The advantages and flexibility of aperture arrays come at the cost of complex signal processing and software systems. Any errors in signal timing, calibration or processing can distort the final image or introduce noise.</p>
1986.  
1987. <p>For this reason, the successful production of the first image is a key validation – it can only happen if the entire system is working.</p>
1988.  
1989. <h2>The shape of the universe and beyond</h2>
1990.  
1991. <figure class="align-right zoomable">
1992.            <a href="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Images showing a patch of sky with increasingly more dots in it." src="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=1800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=1800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=1800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=2262&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=2262&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655564/original/file-20250317-62-hp8r6r.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=2262&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
1993.            <figcaption>
1994.              <span class="caption">As SKA-Low grows, it will see more detail. Simulations show the full telescope may detect up to 600,000 galaxies in the same patch of sky shown in the first test image.</span>
1995.              <span class="attribution"><span class="source">SKAO</span></span>
1996.            </figcaption>
1997.          </figure>
1998.  
1999. <p>Once completed, SKA-Low promises to transform our understanding of the early universe. </p>
2000.  
2001. <p>The antennas of the full telescope will be spread across an area approximately 70 kilometres in diameter, making it the most sensitive low-frequency radio array ever built. </p>
2002.  
2003. <p>This unprecedented sensitivity to low-frequency radio signals will allow scientists to detect the faint signals from the first stars and galaxies that formed after the Big Bang – the so-called “cosmic dawn”. SKA-Low will be the first radio telescope capable of imaging this very early period of our universe.</p>
2004.  
2005. <p>It will also help map the large-scale structure of the universe. We expect the telescope will also provide new insights into cosmic magnetism, the behaviour of interstellar gas, and the mysterious nature of dark matter and dark energy.</p>
2006.  
2007. <p>The sensitivity and resolution of SKA-Low gives it a huge discovery potential. Seven out of the top 10 discoveries from the Hubble Space Telescope were not part of the original science motivation. Like the HST, SKA-Low promises to be a transformative telescope. Who knows what new discoveries await?</p>
2008.  
2009. <h2>What’s next</h2>
2010.  
2011. <p>SKA-Low’s commissioning process will ramp up over the course of the year, as more antenna arrays are installed and brought online. With each additional station, the sensitivity and resolution of the telescope will increase. This growth will also bring greater technical challenges in handling the growing complexity and data rates.</p>
2012.  
2013. <p>By the end of 2025, SKA-Low is expected to have 16 working stations. The increased volume of output data at this stage will be the next major test for the telescope’s software systems.</p>
2014.  
2015. <p>By the end of 2026, the array is planned to expand to 68 working stations at which point it will be the the most sensitive low-frequency radio telescope on Earth.</p>
2016.  
2017. <p>This phase will be the next big test of the end-to-end telescope system. When we get to this stage, the same field you see in the image above will be able to comprehensively map and detect up to 600,000 galaxies. I’m personally looking forward to helping bring it together.</p><img src="https://counter.theconversation.com/content/252382/count.gif" alt="The Conversation" width="1" height="1" />
2018. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Randall Wayth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2019.    <summary>The SKA-Low radio telescope in Western Australia is slowly coming online. It will probe the shape of the universe and study cosmic mysteries.</summary>
2020.    <author>
2021.      <name>Randall Wayth, SKA-Low Senior Commissioning Scientist and Adjunct Associate Professor, Curtin Institute of Radio Astronomy, Curtin University</name>
2022.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/randall-wayth-213195"/>
2023.    </author>
2024.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2025.  </entry>
2026.  <entry>
2027.    <id>tag:theconversation.com,2011:article/244463</id>
2028.    <published>2025-03-17T12:59:40Z</published>
2029.    <updated>2025-03-17T12:59:40Z</updated>
2030.    <link rel="alternate" type="text/html" href="https://theconversation.com/what-was-the-first-thing-scientists-discovered-a-historian-makes-the-case-for-babylonian-astronomy-244463"/>
2031.    <title>What was the first thing scientists discovered? A historian makes the case for Babylonian astronomy</title>
2032.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/651466/original/file-20250225-32-imdki5.jpg?ixlib=rb-4.1.0&amp;amp;rect=474%2C388%2C8702%2C4372&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;Ancient Babylonians looked to the skies to predict what would happen.&lt;/span&gt; &lt;span class="attribution"&gt;&lt;a class="source" href="https://www.gettyimages.com/detail/photo/old-engraved-illustration-of-ancient-babylonia-royalty-free-image/1470481552?adppopup=true"&gt;mikroman6/Moment via Getty Images&lt;/a&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;
2033.  
2034. <p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
2035.  
2036. <hr>
2037.  
2038. <blockquote>
2039. <p><strong>What was the first thing scientists discovered? – Jacob, age 9, Santiago, Panama</strong></p>
2040. </blockquote>
2041.  
2042. <hr>
2043.  
2044. <p>All societies have had ways of understanding nature based on their experiences of it. For example, farmers need to understand the seasons and weather to know when to plant and harvest their crops. Hunters need to understand the lives of animals to know how to hunt them.</p>
2045.  
2046. <p>This kind of understanding of the natural world isn’t quite the same as science though. <a href="https://spaceplace.nasa.gov/science/en/">Science</a> typically refers to knowledge that’s more organized and formal than that. It’s not just an explanation, but a system that uses observations and experiments to build theories that are recorded, passed on to others and built on.</p>
2047.  
2048. <p>With that idea in mind, as a historian of science, my best answer to the question of what the first scientists discovered is Babylonian astronomy.</p>
2049.  
2050. <p><a href="https://www.britannica.com/place/Babylonia">The Babylonians</a> lived from about 2,500 to 4,000 years ago in the area that’s now Iraq. What makes <a href="https://astrobites.org/2023/09/18/the-earliest-astronomers-a-brief-overview-of-babylonian-astronomy/">Babylonian astronomy</a> stand out as being especially scientific is the careful, organized way in which Babylonian scribes – their keepers of knowledge – observed, recorded and eventually mathematically predicted the ways that the Sun, Moon, stars and planets move in the skies.</p>
2051.  
2052. <h2>Babylonian astronomy was uniquely scientific</h2>
2053.  
2054. <p>Before clocks, observing the sky was how people knew the time. During the day you can see the Sun, and at night you can see the stars. Many calendars are based on the skies too. A month is about how long it takes the Moon to go through its phases. A year is one full revolution of the Earth around the Sun.</p>
2055.  
2056. <p>But keeping track of time wasn’t the only way the Babylonians used astronomy. Like today’s world, Babylonia could be both predictable and chaotic. The weather changed with the seasons; crops were planted and harvested; festivals were celebrated; people were born, aged and died, all predictably. But a bad harvest might cause high prices for grains and starvation; a king might die young, causing political upheaval; a disease might kill thousands, all unpredictably. </p>
2057.  
2058. <p>The stars and planets can seem like that, too. The stars are always in the same places in relation to one another, so you can identify constellations, and those constellations rise and set at regular times over the course of a year. But the planets move around – they’re not always in the same places, and <a href="https://www.sciencefocus.com/space/retrograde">sometimes they even seem to stop</a> and move backward in their paths. Sometimes even more spectacular events occur, such as <a href="https://theconversation.com/what-would-a-solar-eclipse-look-like-from-the-moon-an-astronomer-answers-that-and-other-total-eclipse-questions-81308">eclipses</a>.</p>
2059.  
2060. <figure class="align-center zoomable">
2061.            <a href="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="timelapse composite photo of the Moon passing over the Sun during an eclipse" src="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652387/original/file-20250228-32-sxgqjw.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2062.            <figcaption>
2063.              <span class="caption">An eclipse might have seemed like a powerful omen of something that would happen next.</span>
2064.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-this-composite-of-7-photographs-the-moon-passes-by-the-news-photo/2141956427">Josh Edelson/AFP via Getty Images</a></span>
2065.            </figcaption>
2066.          </figure>
2067.  
2068. <p>For the Babylonians, those ideas were linked. They saw changes in the motions of the planets or rare events such as eclipses as signs – omens – about what was going to happen on Earth. For example, they might think the shadow of the Earth moving over the Moon in a certain way during a lunar eclipse meant that a flood would also happen.</p>
2069.  
2070. <p>The scribes kept a book called <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/OmensBasedOnEclipses.html">Enūma Anu Enlil</a> listing omens and their meanings. So if the seemingly changing motions of the heavens could be predicted, maybe earthly events could be, too. This led the scribes to study astronomy.</p>
2071.  
2072. <h2>How Babylonian astronomy worked</h2>
2073.  
2074. <p>The foundation of Babylonian astronomy was kept in a book called <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/ThePloughStar.html">MUL.APIN</a>, meaning “The Plough Star,” the name of a constellation. It recorded the positions of the stars, when in the year they would first be visible, the paths of the Sun and Moon, the periods when the planets would be visible in the night sky, and other fundamental astronomical knowledge.</p>
2075.  
2076. <p>Later, Babylonian scribes began to keep their <a href="https://brunelleschi.imss.fi.it/galileopalazzostrozzi/object/AstronomicalDiary.html">Astronomical Diaries</a>, which contained detailed records of the positions of the Moon and planets along with events on Earth such as the weather and the price of grain. In other words, they recorded their observations of both astronomical omens and the events they might have predicted.</p>
2077.  
2078. <figure class="align-center zoomable">
2079.            <a href="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="columns of white notations on a black background" src="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652389/original/file-20250228-32-1zdnvh.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2080.            <figcaption>
2081.              <span class="caption">Babylonian scribes used cuneiform to write down records of all kinds.</span>
2082.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/old-engraved-illustration-of-ancient-babylonia-royalty-free-image/1470481641">mikroman6/Moment via Getty Images</a></span>
2083.            </figcaption>
2084.          </figure>
2085.  
2086. <p>This kind of careful observation and record-keeping is a major part of science. The Astronomical Diaries were kept for over 700 years, making them maybe the longest-running scientific project ever. </p>
2087.  
2088. <p>The records in the Astronomical Diaries helped Babylonian scribes take another scientific step: predicting astronomical events. One part of this was computing what the Babylonians called goal-years: the number of years it took for a planet to return to the same place on the same day. For example, they computed that the period for Venus was eight Babylonian years. So if Venus was somewhere on a particular day, it would be in the same place on the same day eight years later.</p>
2089.  
2090. <p>By around the fourth century B.C.E., the scribes developed this knowledge into a system of mathematically predicting astronomical events. They made tables called <a href="https://www.metmuseum.org/art/collection/search/321969">ephemerides</a> that showed when these events would happen in the future. So Babylonian scribes succeeded in their project: They made the motions of the Sun, Moon and planets predictable.</p>
2091.  
2092. <h2>Babylonian astronomy and you</h2>
2093.  
2094. <p>MUL.APIN, the Astronomical Diaries, the ephemerides and all of Babylonian astronomy had a major impact on later astronomers, one that continues to today. Greek astronomers used Babylonian observations to make geometric models of planetary motions, part of the long path toward modern astronomy. The ephemerides were the ancestors of astronomical tables, which still exist. For example, <a href="https://eclipse.gsfc.nasa.gov/SEcat5/catalog.html">NASA has a table of eclipses</a> online that goes to the year 3000.</p>
2095.  
2096. <figure class="align-right zoomable">
2097.            <a href="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="analog clock mounted perpendicular to a wall" src="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=995&fit=crop&dpr=1 754w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=995&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/652390/original/file-20250228-32-uvrlas.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=995&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2098.            <figcaption>
2099.              <span class="caption">We tell time using the Babylonian system.</span>
2100.              <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/old-fashioned-clock-in-urban-public-school-hallway-royalty-free-image/1205592295">Catherine McQueen/Moment via Getty Images</a></span>
2101.            </figcaption>
2102.          </figure>
2103.  
2104. <p>But the most familiar thing that comes from Babylonian astronomy is how we tell time. The Babylonians didn’t use a decimal system with units of 10 like we do. Instead, they <a href="https://www.nytimes.com/2013/07/09/science/60-behind-every-second-millenniums-of-history.html">used a sexagesimal system</a>, with units of 60. Babylonian observations were so important that later people kept Babylonian units for astronomy, even though they used a base 10 system for other things.</p>
2105.  
2106. <p>So if you’ve ever wondered why an hour has 60 minutes, and a minute has 60 seconds, it’s because we’ve kept that way of measuring from Babylonian astronomy. Whenever you tell the time, you’re using some of the very oldest science.</p>
2107.  
2108. <hr>
2109.  
2110. <p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
2111.  
2112. <p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/244463/count.gif" alt="The Conversation" width="1" height="1" />
2113. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;James Byrne does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2114.    <summary>Science uses careful, organized observations and tests to construct theories that are recorded, passed on to others and built on.</summary>
2115.    <author>
2116.      <name>James Byrne, Assistant Teaching Professor in the Herbst Program for Engineering, Ethics &amp; Society, University of Colorado Boulder</name>
2117.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/james-byrne-2267808"/>
2118.    </author>
2119.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2120.  </entry>
2121.  <entry>
2122.    <id>tag:theconversation.com,2011:article/252170</id>
2123.    <published>2025-03-17T10:03:59Z</published>
2124.    <updated>2025-03-17T10:03:59Z</updated>
2125.    <link rel="alternate" type="text/html" href="https://theconversation.com/youve-heard-of-the-big-bang-now-astronomers-have-discovered-the-big-wheel-heres-why-its-significant-252170"/>
2126.    <title>You’ve heard of the Big Bang. Now astronomers have discovered the Big Wheel – here’s why it’s significant</title>
2127.    <content type="html">&lt;figure&gt;&lt;img src="https://images.theconversation.com/files/655018/original/file-20250313-56-cwv5zj.png?ixlib=rb-4.1.0&amp;amp;rect=147%2C188%2C1155%2C801&amp;amp;q=45&amp;amp;auto=format&amp;amp;w=496&amp;amp;fit=clip" /&gt;&lt;figcaption&gt;&lt;span class="caption"&gt;The Big Wheel alongside some of its neighbours. &lt;/span&gt; &lt;span class="attribution"&gt;&lt;span class="source"&gt;Weichen Wang et al. (2025)&lt;/span&gt;&lt;/span&gt;&lt;/figcaption&gt;&lt;/figure&gt;&lt;p&gt;Deep observations from the James Webb Space Telescope (JWST) have revealed an exceptionally large galaxy in the early universe. It’s a cosmic giant whose light has travelled over 12 billion years to reach us. We’ve dubbed it the Big Wheel, with our findings &lt;a href="https://www.nature.com/articles/s41550-025-02500-2"&gt;published today in Nature Astronomy&lt;/a&gt;. &lt;/p&gt;
2128.  
2129. <p>This giant disk galaxy existed within the first two billion years after the Big Bang, meaning it formed when the universe was just 15% of its current age. It challenges what we know about how galaxies form.</p>
2130.  
2131. <h2>What is a disk galaxy?</h2>
2132.  
2133. <p>Picture a galaxy like our own <a href="https://science.nasa.gov/resource/the-milky-way-galaxy">Milky Way</a>: a flat, rotating structure made up of stars, gas and dust, often surrounded by an extensive halo of unseen <a href="https://en.wikipedia.org/wiki/Dark_matter">dark matter</a>.</p>
2134.  
2135. <p>Disk galaxies typically have clear spiral arms extending outward from a dense central region. Our Milky Way itself is a disk galaxy, characterised by beautiful spiral arms that wrap around its centre. </p>
2136.  
2137. <figure>
2138.            <iframe width="440" height="260" src="https://www.youtube.com/embed/cuKXQJgkeYg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
2139.            <figcaption><span class="caption">An artist impression of the Milky Way showcasing the dusty spiral structures similar to The Big Wheel.</span></figcaption>
2140.          </figure>
2141.  
2142. <p>Studying disk galaxies, like the Milky Way and the newly discovered Big Wheel, helps us uncover <a href="https://science.nasa.gov/universe/galaxies/evolution/">how galaxies form</a>, grow and evolve across billions of years.</p>
2143.  
2144. <p>These studies are especially significant, as understanding galaxies similar to our own can provide deeper insights into the cosmic history of our galactic home.</p>
2145.  
2146. <h2>A giant surprise</h2>
2147.  
2148. <p>We previously thought galaxy disks form gradually over a long period: either through gas smoothly flowing into galaxies from surrounding space, or by merging with smaller galaxies.</p>
2149.  
2150. <p>Usually, rapid mergers between galaxies would disrupt the delicate spiral structures, turning them into more chaotic shapes. However, the Big Wheel managed to quickly grow to a surprisingly large size without losing its distinctive spiral form. This challenges long-held ideas about the growth of giant galaxies.</p>
2151.  
2152. <p>Our detailed JWST observations show that the Big Wheel is comparable in size and rotational speed to the largest <a href="https://www.jpl.nasa.gov/news/astronomers-discover-colossal-super-spiral-galaxies/">“super-spiral” galaxies</a> in today’s universe. It is three times as big in size as comparable galaxies at that epoch and is one of the most massive galaxies observed in the early cosmos.</p>
2153.  
2154. <p>In fact, its rotation speed places it among galaxies at the high end of what’s called the <a href="https://en.wikipedia.org/wiki/Tully%E2%80%93Fisher_relation">Tully-Fisher relation</a>, a well-known link between a galaxy’s stellar mass and how fast it spins. </p>
2155.  
2156. <p>Remarkably, even though it’s unusually large, the Big Wheel is actively growing at a rate similar to other galaxies at the same cosmic age.</p>
2157.  
2158. <figure class="align-center zoomable">
2159.            <a href="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/655021/original/file-20250313-56-10dn99.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
2160.            <figcaption>
2161.              <span class="caption">The Big Wheel galaxy is seen at the centre. In striking contrast, the bright blue galaxy (upper right) is only about 1.5 billion light years away, making the Big Wheel roughly 50 times farther away. Although both appear a similar size, the enormous distance of the Big Wheel reveals its truly colossal physical scale.</span>
2162.              <span class="attribution"><span class="source">JWST</span></span>
2163.            </figcaption>
2164.          </figure>
2165.  
2166. <h2>Unusually crowded part of space</h2>
2167.  
2168. <p>What makes this even more fascinating is the environment in which the Big Wheel formed.</p>
2169.  
2170. <p>It’s located in an unusually crowded region of space, where galaxies are packed closely together, ten times denser than typical areas of the universe. This dense environment likely provided ideal conditions for the galaxy to grow quickly. It probably experienced mergers that were gentle enough to let the galaxy maintain its spiral disk shape.</p>
2171.  
2172. <p>Additionally, the gas flowing into the galaxy must have aligned well with its rotation, allowing the disk to grow quickly without being disrupted. So, a perfect combination. </p>
2173.  
2174. <figure>
2175.            <iframe width="440" height="260" src="https://www.youtube.com/embed/O674AZ_UKZk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
2176.            <figcaption><span class="caption">An illustration of how a massive spiral galaxy forms and evolves over billions of years. This evolutionary path is similar to real-world galaxies like Andromeda, our closest spiral galaxy neighbour, which also developed distinct spiral arms similar to the Big Wheel.</span></figcaption>
2177.          </figure>
2178.  
2179. <h2>A fortunate finding</h2>
2180.  
2181. <p>Discovering a galaxy like the Big Wheel was incredibly unlikely. We had less than a 2% chance to find this in our survey, according to current galaxy formation models. </p>
2182.  
2183. <p>So, our finding was fortunate, probably because we observed it within an exceptionally dense region, quite different from typical cosmic environments.</p>
2184.  
2185. <p>Besides its mysterious formation, the ultimate fate of the Big Wheel is another intriguing question. Given the dense environment, future mergers might significantly alter its structure, potentially transforming it into a galaxy comparable in mass to the largest ones observed in nearby clusters, such as Virgo.</p>
2186.  
2187. <p>The Big Wheel’s discovery has revealed yet another mystery of the early universe, showing that our current models of galaxy evolution still need refinement.</p>
2188.  
2189. <p>With more observations and discoveries of massive, early galaxies like the Big Wheel, astronomers will be able to unlock more secrets about how the universe built the structures we see today.</p>
2190.  
2191. <hr>
2192. <p>
2193.  <em>
2194.    <strong>
2195.      Read more:
2196.      <a href="https://theconversation.com/from-dead-galaxies-to-mysterious-red-dots-heres-what-the-james-webb-telescope-has-found-in-just-3-years-243592">From dead galaxies to mysterious red dots, here’s what the James Webb telescope has found in just 3 years</a>
2197.    </strong>
2198.  </em>
2199. </p>
2200. <hr>
2201. <img src="https://counter.theconversation.com/content/252170/count.gif" alt="The Conversation" width="1" height="1" />
2202. &lt;p class="fine-print"&gt;&lt;em&gt;&lt;span&gt;Themiya Nanayakkara receives funding from Australian Research Council.&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;</content>
2203.    <summary>This enormous disk object formed soon after the Big Bang, challenging what we know about how galaxies grow.</summary>
2204.    <author>
2205.      <name>Themiya Nanayakkara, Lead Astronomer at the James Webb Australian Data Centre, Swinburne University of Technology</name>
2206.      <foaf:homepage rdf:resource="https://theconversation.com/profiles/themiya-nanayakkara-1324058"/>
2207.    </author>
2208.    <rights>Licensed as Creative Commons – attribution, no derivatives.</rights>
2209.  </entry>
2210. </feed>
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