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 30
    [2]A star filled sky shows bands of green and purple sky glow. In the
        foreground is a grassy field with clouds on the horizon. Most
     remarkably, a series of short streaks appear like a comet's tail up
   from the horizon toward the upper left. Please see the explanation for
                         more detailed information.

                             An Artificial Comet
                   Image Credit & Copyright: [3]Wang Chao

   Explanation: Yes, but can your comet tail do this? No, and what you are
   seeing is not the [4]tail of a [5]comet. The picture features a
   [6]cleverly overlayed time-lapse [7]sequence of a [8]group of
   satellites orbiting [9]Earth together in June. Specifically, these are
   [10]Starlink communications satellites in [11]low Earth orbit
   reflecting back sunlight before sunrise to [12]Inner Mongolia,
   [13]China. Although the satellites appear to the [14]human eye as
   points, the 20-second-long camera exposures caused them to appear as
   short [15]streaks. Currently there are over 9000 [16]Starlinks in
   orbit, with more being [17]launched nearly every week. Other
   [18]satellite constellations are also being planned.

               Explore the Universe: [19]Random APOD Generator
                   Tomorrow's picture: celestial waterfall
     __________________________________________________________________

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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/2512/ArtificialComet_Chao_3000.jpg
   3. mailto: 17662361764 at 163 dot com
   4. https://apod.nasa.gov/apod/ap250128.html
   5. https://science.nasa.gov/solar-system/comets/
   6. https://i.ytimg.com/vi/npW2t0aDMrY/hq720.jpg
   7. https://apod.nasa.gov/apod/image/2512/ArtificialComet_Chao.mp4
   8. https://apod.nasa.gov/apod/ap250614.html
   9. https://science.nasa.gov/earth/earth-observatory/
  10. https://starlink.com/technology
  11. https://www.nasa.gov/humans-in-space/leo-economy-frequently-asked-questions/
  12. https://youtu.be/KagBk62Digg
  13. https://en.wikipedia.org/wiki/China
  14. https://en.wikipedia.org/wiki/Human_eye
  15. https://apod.nasa.gov/apod/ap230107.html
  16. https://www.nasa.gov/centers-and-facilities/ames/nasa-starling-and-spacex-starlink-improve-space-traffic-coordination/
  17. https://apod.nasa.gov/apod/ap251015.html
  18. https://en.wikipedia.org/wiki/Satellite_internet_constellation
  19. https://apod.nasa.gov/apod/random_apod.html
  20. https://apod.nasa.gov/apod/ap251229.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=251230
  30. https://apod.nasa.gov/apod/ap251231.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/