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 w
                    ritten by a professional astronomer.

                              2021 November 15
   [2]The illustration shows a red light-pillar at night over Mt.Etna, an
   erupting volcano in Italy. Please see the explanation for more detailed
                                information.

                       Light Pillar over Volcanic Etna
                 Image Credit & Copyright: [3]Giancarlo Tinč

   Explanation: What happening above that volcano? Something very unusual
   -- a volcanic [4]light pillar. More typically, light pillars are caused
   by sunlight and so appear as a bright column that extends upward above
   a rising or setting [5]Sun. Alternatively, other light pillars --
   [6]some [7]quite [8]colorful -- have been recorded above street and
   house lights. This light [9]pillar, though, was illuminated by the red
   light emitted by the glowing magma of an [10]erupting volcano. The
   volcano is [11]Italy's [12]Mount Etna, and the [13]featured image was
   [14]captured with a single shot a few hours after sunset in mid-June.
   Freezing temperatures above the volcano's [15]ash cloud created
   [16]ice-crystals either in [17]cirrus clouds high above the volcano --
   or in condensed water vapor expelled by [18]Mount Etna. These [19]ice
   crystals -- mostly [20]flat toward the ground but fluttering -- then
   reflected away light from the [21]volcano's caldera.

              Explore Your Universe: [22]Random APOD Generator
                       Tomorrow's picture: meteor flow
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    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Phillip Newman [38]Specific rights apply.
              [39]NASA Web Privacy Policy and Important Notices
                A service of: [40]ASD at [41]NASA / [42]GSFC
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2111/EtnaLightPillar_Tine_5100.jpg
   3. https://www.giancarlotine.it/biografia-ed-esperienze-fotografiche-giancarlo-tine/
   4. https://en.wikipedia.org/wiki/Light_pillar
   5. https://solarsystem.nasa.gov/solar-system/sun/by-the-numbers/
   6. https://apod.nasa.gov/apod/ap181024.html
   7. https://apod.nasa.gov/apod/ap160208.html
   8. https://apod.nasa.gov/apod/ap131218.html
   9. https://www.atoptics.co.uk/halo/pillar.htm
  10. https://youtu.be/z01KTFhA34o
  11. https://en.wikipedia.org/wiki/Italy
  12. https://en.wikipedia.org/wiki/Mount_Etna
  13. https://www.giancarlotine.it/fotografia-di-paesaggio/foto-gallery-etna/
  14. https://www.atoptics.co.uk/fza263.htm
  15. https://apod.nasa.gov/apod/ap190512.html
  16. https://www.atoptics.co.uk/halo/platcol.htm
  17. https://scool.larc.nasa.gov/GLOBE/cirrus.html
  18. https://apod.nasa.gov/apod/ap030416.html
  19. https://www.atoptics.co.uk/halo/lpil.htm
  20. https://mrbosscat.com/wp-content/uploads/2021/03/Cat-lying-flat-on-stomach-1536x864.jpg
  21. https://youtu.be/gbRdvpTdQdI
  22. http://apod.nasa.gov/apod/random_apod.html
  23. https://apod.nasa.gov/apod/ap211114.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.nasa.gov/apod.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. http://asterisk.apod.com/discuss_apod.php?date=211115
  33. https://apod.nasa.gov/apod/ap211116.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  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://astrophysics.gsfc.nasa.gov/
  41. https://www.nasa.gov/
  42. https://www.nasa.gov/centers/goddard/
  43. http://www.mtu.edu/