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 July 18
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                             Shadow and Rainbow
                  Image Credit & [3]License: Dave Loschiavo

   Explanation: At sunset, an alignment of rainbow and mountain shadow was
   captured in this remarkable snapshot. The stunning view was recorded
   from a fire lookout on Smith Peak in the Plumas National Forest near
   Portola, California on July 13. Still, near sunset it's no accident
   that the majestic mountain shadow seems to point to the center of the
   graceful [4]rainbow arc. Due to perspective and the long line of sight
   the [5]mountain shadow naturally forms a [6]tapering triangular shape,
   its apex positioned at the point opposite the Sun on the horizon.
   Following thunderstorms across the region, the [7]rainbow arcs across
   the early evening sky, with its colorful and characteristic 42 degree
   arc formed as sunlight is refracted and reflected by the atmospheric
   water droplets. The geometric center of a rainbow arc lies at the
   antisolar point. And in this scene from the golden hour on [8]planet
   Earth, that's also oposite the setting Sun along the distant horizon.

                   Tomorrow's picture: it came from space
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      Authors & editors: [20]Robert Nemiroff ([21]MTU) & Jerry Bonnell
                                 ([22]UMCP)
          NASA Official: Amber Straughn [23]Specific rights apply.
            [24]NASA Web Privacy, [25]Accessibility, [26]Notices;
                A service of: [27]ASD at [28]NASA / [29]GSFC,
                         [30]NASA Science Activation
                           & [31]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2607/ShadowandRainbow_Loschiavo.jpg
   3. https://creativecommons.org/licenses/by-sa/4.0/deed.en
   4. https://apod.nasa.gov/apod/ap230313.html
   5. https://apod.nasa.gov/apod/ap200314.html
   6. https://apod.nasa.gov/apod/ap161021.html
   7. https://www.nesdis.noaa.gov/about/k-12-education/optical-phenomena/what-causes-rainbow
   8. https://apod.nasa.gov/apod/ap191011.html
   9. https://apod.nasa.gov/apod/ap260717.html
  10. https://apod.nasa.gov/apod/archivepix.html
  11. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  12. https://apod.nasa.gov/apod/lib/aptree.html
  13. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  14. https://apod.nasa.gov/apod/calendar/allyears.html
  15. https://apod.com/feed.rss
  16. https://apod.nasa.gov/apod/lib/edlinks.html
  17. https://apod.nasa.gov/apod/lib/about_apod.html
  18. https://asterisk.apod.com/discuss_apod.php?date=260718
  19. https://apod.nasa.gov/apod/ap260719.html
  20. https://www.mtu.edu/physics/department/faculty/nemiroff/
  21. https://www.mtu.edu/physics
  22. https://www.astro.umd.edu/
  23. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  24. https://www.nasa.gov/about/highlights/HP_Privacy.html
  25. https://www.nasa.gov/general/accessibility/
  26. https://www.nasa.gov/privacy/
  27. https://astrophysics.gsfc.nasa.gov/
  28. https://www.nasa.gov/
  29. https://www.nasa.gov/centers/goddard/
  30. https://science.nasa.gov/learners
  31. http://www.mtu.edu/