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.

                                2026 June 25
    [2]A landscape with an open horizon shows sunset color and coverging
                               rays of light.

                      Anticrepuscular Rays over Sicily
              Image Credit & Copyright: [3]Marcella Giulia Pace
     Text: [4]Cecilia Chirenti ([5]NASA [6]GSFC, [7]UMCP, [8]CRESST II)

   Explanation: The [9]Sun has just set... in the opposite side of the
   sky. Pictured [10]here are [11]anticrepuscular rays apparently
   converging in the east in this image of the [12]limestone plateau in
   the heart of the [13]Hyblaean Mountains of southeastern [14]Sicily, in
   Italy. How were these anticrepuscular rays formed, if the Sun
   [15]wasn't there? After the Sun set (in the west, as usual) its light
   still illuminated a [16]cloud higher up in the sky. Partially blocked
   by the cloud, the sunlight produced [17]patterns of light and shadow,
   crossing the sky in parallel lines. Perspective makes it look like they
   converge in the east, in the same way that [18]train tracks appear to
   meet in the distance. This effect can also happen at [19]sunrise, only
   the directions are exchanged. In [20]rare cases, both [21]crepuscular
   and anticrepuscular rays can be seen [22]at the same time.

                      Tomorrow's picture: What's next?
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    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Amber Straughn [38]Specific rights apply.
            [39]NASA Web Privacy, [40]Accessibility, [41]Notices;
                A service of: [42]ASD at [43]NASA / [44]GSFC,
                         [45]NASA Science Activation
                           & [46]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2606/crepuscular2.jpg
   3. https://www.instagram.com/marcella_giulia_pace/
   4. https://science.gsfc.nasa.gov/sci/bio/cecilia.chirenti
   5. https://www.nasa.gov/
   6. https://www.nasa.gov/goddard/
   7. https://www.astro.umd.edu/people/cecilia-chirenti
   8. https://cresst2.umd.edu/
   9. https://science.nasa.gov/sun/
  10. https://www.instagram.com/p/DZxl4R-gi73/?img_index=1
  11. https://en.wikipedia.org/wiki/Anticrepuscular_rays
  12. https://en.wikipedia.org/wiki/Geology_of_Sicily
  13. https://www.italia.it/en/sicily/hyblaean-mountains
  14. https://en.wikipedia.org/wiki/Sicily
  15. https://images.unsplash.com/photo-1598398386929-4d5370672e9f
  16. https://www.instagram.com/p/DZxl4R-gi73/?img_index=2
  17. https://apod.nasa.gov/apod/ap200318.html
  18. https://images.unsplash.com/photo-1588127727253-e5f2faf4f541
  19. https://apod.nasa.gov/apod/ap240921.html
  20. https://cloudappreciationsociety.org/cloud-library/anti-crepuscular-rays/
  21. https://apod.nasa.gov/apod/ap100811.html
  22. https://earthsky.org/earth/how-to-see-anticrepuscular-rays/
  23. https://apod.nasa.gov/apod/ap260624.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.com/feed.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. https://asterisk.apod.com/discuss_apod.php?date=260625
  33. https://apod.nasa.gov/apod/ap260626.html
  34. https://www.mtu.edu/physics/department/faculty/nemiroff/
  35. https://www.mtu.edu/physics/
  36. https://inspirehep.net/authors/1073087
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://www.nasa.gov/general/accessibility/
  41. https://www.nasa.gov/privacy/
  42. https://science.gsfc.nasa.gov/astrophysics/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. https://science.nasa.gov/learn/about-science-activation/
  46. http://www.mtu.edu/