Astronomy Picture of the Day [1]Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2025 December 1 [2]A starfield is shown around a comet. The green coma of the comet is on the lower left. A meandering blue-tinted tail goes off to the upper right. A slight anti-tail is seen from the coma toward the lower left. Please see the explanation for more detailed information. 3I ATLAS: Tails of an Interstellar Comet Image Credit & Copyright: Victor Sabet & [3]Julien De Winter Explanation: How typical is our Solar System? Studying [4]3I/ATLAS, a comet just passing through, is providing clues. Confirmed previous interstellar visitors include an [5]asteroid, a [6]comet, a [7]meteor, and a [8]gas wind dominated by hydrogen and helium. [9]Comet 3I/ATLAS appears [10]relatively normal when compared to [11]Solar [12]System [13]comets, therefore providing more evidence that [14]our Solar System is a somewhat typical star system. For example, Comet 3I/ATLAS has a broadly similar [15]chemical composition and [16]ejected dust. The [17]featured image was captured last week from [18]Texas and shows a [19]green coma, a wandering [20]blue-tinted ion tail likely deflected by our [21]Sun's wind, and a slight [22]anti-tail, all typical cometary attributes. The comet, visible with [23]a telescope, passed its closest to the Sun in late October and will pass its closest to the Earth in mid-December, after which it will return to [24]interstellar space and never return. Explore the Universe: [25]Random APOD Generator Tomorrow's picture: active galaxy __________________________________________________________________ [26]< | [27]Archive | [28]Submissions | [29]Index | [30]Search | [31]Calendar | [32]RSS | [33]Education | [34]About APOD | [35]Discuss | [36]> __________________________________________________________________ Authors & editors: [37]Robert Nemiroff ([38]MTU) & [39]Jerry Bonnell ([40]UMCP) NASA Official: Amber Straughn [41]Specific rights apply. [42]NASA Web Privacy, [43]Accessibility, [44]Notices; A service of: [45]ASD at [46]NASA / [47]GSFC, [48]NASA Science Activation & [49]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2512/Comet3I_SabetWinter_4243.jpg 3. https://www.instagram.com/dwj85 4. https://science.nasa.gov/blogs/planetary-defense/2025/07/02/nasa-discovers-interstellar-comet-moving-through-solar-system/ 5. https://en.wikipedia.org/wiki/1I/ʻOumuamua 6. https://apod.nasa.gov/apod/ap220305.html 7. https://www.npr.org/2022/04/14/1092869771/interstellar-meteor-hit-earth-in-2014 8. https://sci.esa.int/web/ulysses/-/35853-the-flow-of-interstellar-helium-in-the-solar-system 9. https://en.wikipedia.org/wiki/3I/ATLAS 10. https://www.skyatnightmagazine.com/news/3i-atlas-not-aliens 11. https://apod.nasa.gov/apod/ap090207.html 12. https://apod.nasa.gov/apod/ap200606.html 13. https://apod.nasa.gov/apod/ap231020.html 14. https://science.nasa.gov/solar-system/solar-system-facts/ 15. https://astrobiology.nasa.gov/nai/annual-reports/2012/uh/the-chemical-composition-of-comets/index.html 16. https://apod.nasa.gov/apod/ap231126.html 17. https://app.astrobin.com/i/jtmq82 18. https://en.wikipedia.org/wiki/Texas 19. https://www.science.org/content/article/why-do-some-comets-glow-green 20. https://astronomy.swin.edu.au/cosmos/c/Cometary+Gas+Tail 21. https://science.nasa.gov/sun/what-is-the-solar-wind/ 22. https://en.wikipedia.org/wiki/Comet_tail#Anti-tail 23. https://1funny.com/wp-content/uploads/2010/12/dog-telescope.jpg 24. https://apod.nasa.gov/apod/ap241222.html 25. https://apod.nasa.gov/apod/random_apod.html 26. https://apod.nasa.gov/apod/ap251130.html 27. https://apod.nasa.gov/apod/archivepix.html 28. https://apod.nasa.gov/apod/lib/apsubmit2015.html 29. https://apod.nasa.gov/apod/lib/aptree.html 30. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 31. https://apod.nasa.gov/apod/calendar/allyears.html 32. https://apod.com/feed.rss 33. https://apod.nasa.gov/apod/lib/edlinks.html 34. https://apod.nasa.gov/apod/lib/about_apod.html 35. https://asterisk.apod.com/discuss_apod.php?date=251201 36. https://apod.nasa.gov/apod/ap251202.html 37. http://www.phy.mtu.edu/faculty/Nemiroff.html 38. http://www.phy.mtu.edu/ 39. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 40. http://www.astro.umd.edu/ 41. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 42. https://www.nasa.gov/about/highlights/HP_Privacy.html 43. https://www.nasa.gov/general/accessibility/ 44. https://www.nasa.gov/privacy/ 45. https://astrophysics.gsfc.nasa.gov/ 46. https://www.nasa.gov/ 47. https://www.nasa.gov/centers/goddard/ 48. https://science.nasa.gov/learners 49. http://www.mtu.edu/