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.

                              2022 December 21
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                    Sun Halo at Sixty-three Degrees North
                Image Credit & [3]Copyright: [4]Goran Strand

   Explanation: Happy Solstice! [5]Today is the December solstice, marking
   an astronomical beginning of summer in the southern hemisphere and
   winter in the north. On its [6]yearly trek through planet Earth's
   skies, at this solstice the Sun reaches its southern most declination,
   [7]23.5 degrees south, at 21:48 [8]UTC. About 4 days ago the Sun was
   near this seasonal southern limit and so only just above the horizon at
   local noon over Ostersund in central Sweden. This view looking over the
   far northern lakeside city finds the midday Sun with a beautiful
   [9]solar ice halo. Naturally occurring [10]atmospheric ice crystals can
   produce the [11]tantalizing halo displays, refracting and reflecting
   the sunlight through their hexagonal geometry. Still, with the Sun low
   and near the horizon in the clear sky, likely sources of the ice
   crystals producing this intense halo are snow cannons. Operating at a
   local ski area, the snowmaking machines create a visible plume at the
   top of the nearby island Froson toward the right side of the panorama.

                     Tomorrow's picture: northern spiral
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    Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell
                                 ([26]UMCP)
          NASA Official: Phillip Newman [27]Specific rights apply.
              [28]NASA Web Privacy Policy and Important Notices
                A service of: [29]ASD at [30]NASA / [31]GSFC,
                         [32]NASA Science Activation
                           & [33]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2212/GS_20221217_Solhalo_Pan_v3.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://astrofotografen.se/
   5. https://earthsky.org/astronomy-essentials/everything-you-need-to-know-december-solstice/
   6. https://apod.nasa.gov/apod/ap190621.html
   7. https://earthobservatory.nasa.gov/images/52248/seeing-equinoxes-and-solstices-from-space
   8. https://earthsky.org/astronomy-essentials/universal-time/
   9. https://apod.nasa.gov/apod/ap210610.html
  10. https://atoptics.co.uk/
  11. https://apod.nasa.gov/apod/ap181221.html
  12. https://apod.nasa.gov/apod/ap221220.html
  13. https://apod.nasa.gov/apod/archivepix.html
  14. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  15. https://apod.nasa.gov/apod/lib/aptree.html
  16. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  17. https://apod.nasa.gov/apod/calendar/allyears.html
  18. https://apod.nasa.gov/apod.rss
  19. https://apod.nasa.gov/apod/lib/edlinks.html
  20. https://apod.nasa.gov/apod/lib/about_apod.html
  21. http://asterisk.apod.com/discuss_apod.php?date=221221
  22. https://apod.nasa.gov/apod/ap221222.html
  23. http://www.phy.mtu.edu/faculty/Nemiroff.html
  24. http://www.phy.mtu.edu/
  25. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  26. http://www.astro.umd.edu/
  27. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  28. https://www.nasa.gov/about/highlights/HP_Privacy.html
  29. https://astrophysics.gsfc.nasa.gov/
  30. https://www.nasa.gov/
  31. https://www.nasa.gov/centers/goddard/
  32. https://science.nasa.gov/learners
  33. http://www.mtu.edu/