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.

                                 2020 May 30
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                  Green Flashes: Sun, Moon, Venus, Mercury
            Image Credit & [3]Copyright: [4]Marcella Giulia Pace

   Explanation: [5]Follow a sunset on a clear day against a distant
   horizon and you might glimpse green just as the Sun disappears from
   view. [6]The green flash is caused by refraction of light rays
   traveling to the eye over a long path through the atmosphere. Shorter
   wavelengths refract more strongly than longer redder wavelengths and
   the separation of colors lends a green hue to the last [7]visible
   vestige of the solar disk. It's harder to see a [8]green flash from the
   Moon, not to mention the diminutive disks [9]of Venus and Mercury. But
   a telescope or telephoto lens and camera can help catch this
   tantalizing result of atmospheric refraction when the celestial bodies
   are near the horizon. From Sicily, the top panels were recorded on
   March 18, 2019 for the Sun and May 8, 2020 for the Moon. Also from the
   Mediterranean island, the bottom panels were shot during the twilight
   apparition [10]of Venus and Mercury near the western horizon on May 24.

                      Tomorrow's picture: green arches
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    Authors & editors: [22]Robert Nemiroff ([23]MTU) & [24]Jerry Bonnell
                                 ([25]UMCP)
          NASA Official: Phillip Newman [26]Specific rights apply.
              [27]NASA Web Privacy Policy and Important Notices
                A service of: [28]ASD at [29]NASA / [30]GSFC
                           & [31]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2005/GreenFlashdidacopia2.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://greenflash.photo/about-me/
   5. https://www.nasa.gov/exploration/commercial/crew/index.html
   6. https://www.atoptics.co.uk/atoptics/gf1.htm
   7. https://apod.nasa.gov/apod/ap160409.html
   8. https://apod.nasa.gov/apod/ap150605.html
   9. https://earthsky.org/todays-image/venus-green-flash
  10. https://apod.nasa.gov/apod/ap200529.html
  11. https://apod.nasa.gov/apod/ap200529.html
  12. https://apod.nasa.gov/apod/archivepix.html
  13. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  14. https://apod.nasa.gov/apod/lib/aptree.html
  15. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  16. https://apod.nasa.gov/apod/calendar/allyears.html
  17. https://apod.nasa.gov/apod.rss
  18. https://apod.nasa.gov/apod/lib/edlinks.html
  19. https://apod.nasa.gov/apod/lib/about_apod.html
  20. http://asterisk.apod.com/discuss_apod.php?date=200530
  21. https://apod.nasa.gov/apod/ap200531.html
  22. http://www.phy.mtu.edu/faculty/Nemiroff.html
  23. http://www.phy.mtu.edu/
  24. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  25. http://www.astro.umd.edu/
  26. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  27. https://www.nasa.gov/about/highlights/HP_Privacy.html
  28. https://astrophysics.gsfc.nasa.gov/
  29. https://www.nasa.gov/
  30. https://www.nasa.gov/centers/goddard/
  31. http://www.mtu.edu/