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 January 7
   [2]A star field appears above a town at night. The left part of the sky
   shows a pinkish-red glow that is an aurora, while the right part of the
   sky shows a smoother and darker glow that is a SAR arc. Please see the
                 explanation for more detailed information.

                       A New Year's Aurora and SAR Arc
                Image Credit & Copyright: [3]Alessandra Masi

   Explanation: It was a new year, and the sky was doubly red. The new
   year meant that the [4]Earth had returned to its usual place in its
   orbit on January 1, a place a few days before its [5]closest approach
   to the [6]Sun. The first of the two red skyglows, on the left, was a
   [7]red aurora, complete with [8]vertical rays, caused by a [9]blast
   from the Sun pushing charged particles into Earth's atmosphere. The
   second red glow, most prominent on the far right, was possibly a
   [10]SAR arc caused by a river of charged particles flowing across
   [11]Earth's atmosphere. Although both appear red, the [12]slight color
   difference is likely due to the aurora being emitted by both oxygen and
   nitrogen, whereas the higher [13]SAR arc was possibly emitted more
   purely by atmospheric oxygen. The [14]featured image was taken on
   January 1 from near [15]Pieve di Cadore in [16]Italy.

                 Portal Universe: [17]Random APOD Generator
                   Tomorrow's picture: supernovas (plural)
     __________________________________________________________________

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    Authors & editors: [29]Robert Nemiroff ([30]MTU) & [31]Jerry Bonnell
                                 ([32]UMCP)
          NASA Official: Amber Straughn [33]Specific rights apply.
            [34]NASA Web Privacy, [35]Accessibility, [36]Notices;
                A service of: [37]ASD at [38]NASA / [39]GSFC,
                         [40]NASA Science Activation
                           & [41]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2501/AuroraSar_Masi_1280.jpg
   3. https://www.instagram.com/alessandramasi_21/
   4. https://science.nasa.gov/earth/facts/
   5. https://apod.nasa.gov/apod/ap250104.html
   6. https://science.nasa.gov/sun/
   7. https://img.apmcdn.org/7a6d073179a68e50dbf9833adb72225a76554a51/uncropped/0011cd-20241011-nws-aurora-colors-webp1000.webp
   8. https://apod.nasa.gov/apod/ap061218.html
   9. https://apod.nasa.gov/apod/ap240818.html
  10. https://eos.org/research-spotlights/from-sar-arc-to-steve-an-atmospheric-evolution
  11. https://science.nasa.gov/earth/earth-atmosphere/earths-atmosphere-a-multi-layered-cake/
  12. https://www.reddit.com/media?url=https://preview.redd.it/why-do-my-cats-from-the-same-litter-look-so-different-v0-gp1xxwpi7p9c1.jpeg?width=320&crop=smart&auto=webp&s=8de4979921dc03f68f8f5f58e849277569ff450e
  13. https://apod.nasa.gov/apod/ap231111.html
  14. https://www.instagram.com/p/DEVPPQENcXD
  15. https://youtu.be/HktA997YN0Y
  16. https://en.wikipedia.org/wiki/Italy
  17. https://apod.nasa.gov/apod/random_apod.html
  18. https://apod.nasa.gov/apod/ap250106.html
  19. https://apod.nasa.gov/apod/archivepix.html
  20. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  21. https://apod.nasa.gov/apod/lib/aptree.html
  22. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  23. https://apod.nasa.gov/apod/calendar/allyears.html
  24. https://apod.com/feed.rss
  25. https://apod.nasa.gov/apod/lib/edlinks.html
  26. https://apod.nasa.gov/apod/lib/about_apod.html
  27. https://asterisk.apod.com/discuss_apod.php?date=250107
  28. https://apod.nasa.gov/apod/ap250108.html
  29. http://www.phy.mtu.edu/faculty/Nemiroff.html
  30. http://www.phy.mtu.edu/
  31. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  32. http://www.astro.umd.edu/
  33. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  34. https://www.nasa.gov/about/highlights/HP_Privacy.html
  35. https://www.nasa.gov/general/accessibility/
  36. https://www.nasa.gov/privacy/
  37. https://astrophysics.gsfc.nasa.gov/
  38. https://www.nasa.gov/
  39. https://www.nasa.gov/centers/goddard/
  40. https://science.nasa.gov/learners
  41. http://www.mtu.edu/