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 __________________________________________________________________ [23]< | [24]Archive | [25]Submissions | [26]Index | [27]Search | [28]Calendar | [29]RSS | [30]Education | [31]About APOD | [32]Discuss | [33]> __________________________________________________________________ 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/