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.

                                 2021 May 30
   [2]The picture shows green aurora through odd lenticular clouds. Please
             see the explanation for more detailed information.

                             Aurora over Clouds
                Image Credit & Copyright: [3]Daniele Boffelli

   Explanation: Auroras usually occur high above the clouds. The
   [4]auroral glow is created when fast-moving particles ejected from the
   Sun impact the [5]Earth's magnetosphere, from which charged particles
   spiral along the [6]Earth's magnetic field to strike atoms and
   molecules high in the [7]Earth's atmosphere. An [8]oxygen atom, for
   example, will glow in the green light commonly emitted by an [9]aurora
   after being energized by such a collision. The lowest part of an
   [10]aurora will typically occur about 100 kilometers up, while most
   clouds exist only below about 10 kilometers. The relative heights of
   clouds and [11]auroras are shown clearly in the [12]featured picture in
   2015 from [13]Dyrholaey, [14]Iceland. There, a determined
   astrophotographer withstood [15]high winds and initially overcast skies
   in an attempt to capture aurora over a [16]picturesque lighthouse, only
   to take, by chance, the featured picture including elongated
   [17]lenticular clouds, [18]along the way.

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                     Tomorrow's picture: that’s a moon
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    Authors & editors: [35]Robert Nemiroff ([36]MTU) & [37]Jerry Bonnell
                                 ([38]UMCP)
          NASA Official: Phillip Newman [39]Specific rights apply.
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                A service of: [41]ASD at [42]NASA / [43]GSFC
                           & [44]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2105/AuroraClouds_Boffelli_2048.jpg
   3. https://www.facebook.com/danieleboffellifotografia/
   4. http://www.atoptics.co.uk/highsky/auror3.htm
   5. http://science.nasa.gov/heliophysics/focus-areas/magnetosphere-ionosphere/
   6. http://www.nasa.gov/mission_pages/sunearth/news/gallery/Earths-magneticfieldlines-dipole.html
   7. http://www.nasa.gov/mission_pages/sunearth/science/atmosphere-layers2.html
   8. http://periodic.lanl.gov/8.shtml
   9. https://apod.nasa.gov/apod/ap141103.html
  10. https://apod.nasa.gov/apod/ap130609.html
  11. http://www.gi.alaska.edu/AuroraForecast
  12. https://www.facebook.com/NikonItalia/photos/a.380376239661.158168.147466084661/10153716437154662/
  13. https://youtu.be/_Om267wp-h4
  14. https://en.wikipedia.org/wiki/Iceland
  15. https://i2.wp.com/puppytoob.com/wp-content/uploads/2013/04/Dogs_In_Wind_9.jpg?resize=619,411&ssl=1
  16. https://apod.nasa.gov/apod/image/1511/DSC_6447.jpg
  17. https://apod.nasa.gov/apod/ap090203.html
  18. https://quoteinvestigator.com/2012/05/06/other-plans/
  19. https://www.instagram.com/astronomypicturesdaily/
  20. https://www.instagram.com/skypixapod/
  21. https://www.instagram.com/apod.id/
  22. https://www.instagram.com/avastarapod/
  23. https://www.instagram.com/apodbrasil/
  24. https://apod.nasa.gov/apod/ap210529.html
  25. https://apod.nasa.gov/apod/archivepix.html
  26. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  27. https://apod.nasa.gov/apod/lib/aptree.html
  28. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  29. https://apod.nasa.gov/apod/calendar/allyears.html
  30. https://apod.nasa.gov/apod.rss
  31. https://apod.nasa.gov/apod/lib/edlinks.html
  32. https://apod.nasa.gov/apod/lib/about_apod.html
  33. http://asterisk.apod.com/discuss_apod.php?date=210530
  34. https://apod.nasa.gov/apod/ap210531.html
  35. http://www.phy.mtu.edu/faculty/Nemiroff.html
  36. http://www.phy.mtu.edu/
  37. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  38. http://www.astro.umd.edu/
  39. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  40. https://www.nasa.gov/about/highlights/HP_Privacy.html
  41. https://astrophysics.gsfc.nasa.gov/
  42. https://www.nasa.gov/
  43. https://www.nasa.gov/centers/goddard/
  44. http://www.mtu.edu/