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 September 29
   [2]A starfield is shown that has two short streaks running diagonally.
    At closer inspection, they are two comets both with white-green heads
        and white tails. Please see the explanation for more detailed
                                information.

                        Two Camera Comets in One Sky
              Image Credit & Copyright: [3]Luc Perrot ([4]TWAN)

   Explanation: It may look like these comets are racing, but they are
   not. Comets [5]C/2025 K1 ATLAS (left) and [6]C/2025 R2 SWAN (right)
   appeared near each other by chance last week in the [7]featured image
   taken from France's [8]Reunion [9]Island in the southern [10]Indian
   Ocean. Fainter [11]Comet ATLAS is approaching our Sun and will reach
   its closest approach in early October when it is also expected to be
   its brightest -- although still only [12]likely visible with long
   exposures on a camera. The brighter comet, nicknamed [13]SWAN25B, is
   now headed away from our [14]Sun, although its closest approach to
   Earth is expected in mid-October, when [15]optimistic estimates have it
   becoming bright enough to see with the unaided eye. Each [16]comet has
   a greenish [17]coma of expelled gas and an [18]ion tail pointing away
   from the Sun.

                     Growing Gallery: [19]Comet SWAN25B
                  Tomorrow's picture: a third camera comet
     __________________________________________________________________

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     __________________________________________________________________

    Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell
                                 ([34]UMCP)
          NASA Official: Amber Straughn [35]Specific rights apply.
            [36]NASA Web Privacy, [37]Accessibility, [38]Notices;
                A service of: [39]ASD at [40]NASA / [41]GSFC,
                         [42]NASA Science Activation
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2509/TwoComets_Perrot_960.jpg
   3. https://www.lucperrot.fr/bio
   4. https://twanight.org/profile/luc-perrot/
   5. https://en.wikipedia.org/wiki/C/2025_K1_(ATLAS)
   6. https://en.wikipedia.org/wiki/C/2025_R2_(SWAN)
   7. https://www.facebook.com/photo?fbid=1310580907110669&set=a.216372196531551
   8. https://en.wikipedia.org/wiki/Réunion
   9. https://youtu.be/MUEVBSiWWR8
  10. https://en.wikipedia.org/wiki/Indian_Ocean
  11. https://www.skyatnightmagazine.com/news/c-2025-k1-atlas
  12. https://theskylive.com/c2025k1-info
  13. https://apod.nasa.gov/apod/ap250916.html
  14. https://science.nasa.gov/sun/
  15. https://images.ctfassets.net/sfnkq8lmu5d7/tnPfU8draFS8Kuasr1CAr/9e6282b240cdf13024cc13fa868d6636/2024-10-22_How_long_can_a_puppy_be_left_alone
  16. https://science.nasa.gov/solar-system/comets/facts/
  17. https://en.wikipedia.org/wiki/Coma_(comet)
  18. https://apod.nasa.gov/apod/ap250918.html
  19. https://www.facebook.com/media/set/?set=a.782042584524321&type=3
  20. https://apod.nasa.gov/apod/ap250928.html
  21. https://apod.nasa.gov/apod/archivepix.html
  22. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  23. https://apod.nasa.gov/apod/lib/aptree.html
  24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  25. https://apod.nasa.gov/apod/calendar/allyears.html
  26. https://apod.com/feed.rss
  27. https://apod.nasa.gov/apod/lib/edlinks.html
  28. https://apod.nasa.gov/apod/lib/about_apod.html
  29. https://asterisk.apod.com/discuss_apod.php?date=250929
  30. https://apod.nasa.gov/apod/ap250930.html
  31. http://www.phy.mtu.edu/faculty/Nemiroff.html
  32. http://www.phy.mtu.edu/
  33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  34. http://www.astro.umd.edu/
  35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  36. https://www.nasa.gov/about/highlights/HP_Privacy.html
  37. https://www.nasa.gov/general/accessibility/
  38. https://www.nasa.gov/privacy/
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. https://science.nasa.gov/learners
  43. http://www.mtu.edu/