¿

                        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 February 1
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                         Lunar Halo over Snowy Trees
                  Image Credit & Copyright: [3]Göran Strand

   Explanation: Have you ever seen a halo around the [4]Moon? This fairly
   common sight occurs when [5]high thin clouds containing millions of
   tiny [6]ice crystals cover much of the sky. Each [7]ice crystal acts
   like a miniature lens. Because [8]most of the crystals have a similar
   elongated hexagonal shape, light entering one crystal face and exiting
   through the opposing face refracts 22 degrees, which corresponds to the
   radius of the [9]Moon Halo. A similar [10]Sun Halo may be visible
   during the day. Exactly [11]how ice-crystals form in clouds remains a
   topic of research. In the [12]featured image taken last week from
   [13]Östersund, [14]Sweden, a complete [15]lunar halo was captured over
   [16]snowy trees and [17]rabbit tracks.

      APOD is available via Instagram: in [18]English, [19]Indonesian,
                       [20]Persian, and [21]Portuguese
                 Tomorrow's picture: meteor streak and drift
     __________________________________________________________________

      [22]< | [23]Archive | [24]Submissions | [25]Index | [26]Search |
   [27]Calendar | [28]RSS | [29]Education | [30]About APOD | [31]Discuss |
                                    [32]>
     __________________________________________________________________

    Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell
                                 ([36]UMCP)
          NASA Official: Phillip Newman [37]Specific rights apply.
              [38]NASA Web Privacy Policy and Important Notices
                A service of: [39]ASD at [40]NASA / [41]GSFC
                           & [42]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2102/LunarHalo_Strand_1500.jpg
   3. http://www.astrofotografen.se/
   4. https://solarsystem.nasa.gov/moons/earths-moon/in-depth/
   5. https://en.wikipedia.org/wiki/Cirrus_cloud
   6. http://en.wikipedia.org/wiki/Ice_crystals
   7. https://www.atoptics.co.uk/halo/circ1.htm
   8. http://www.everythingweather.com/lightning/ice.shtml
   9. https://www.atoptics.co.uk/halo/circmoon.htm
  10. https://apod.nasa.gov/apod/ap150403.html
  11. http://www.cas.manchester.ac.uk/resactivities/cloudphysics/topics/formation/
  12. https://www.instagram.com/p/CKgTQ8BhJ1y/
  13. https://youtu.be/E0z1BqhtyLA
  14. https://en.wikipedia.org/wiki/Sweden
  15. https://apod.nasa.gov/apod/ap200224.html
  16. https://apod.nasa.gov/apod/ap170110.html
  17. https://www.rd.com/wp-content/uploads/2020/04/GettyImages-694542042-e1586274805503.jpg
  18. https://www.instagram.com/astronomypicturesdaily/
  19. https://www.instagram.com/apod.id/
  20. https://www.instagram.com/avastarapod/
  21. https://www.instagram.com/apodbrasil/
  22. https://apod.nasa.gov/apod/ap210131.html
  23. https://apod.nasa.gov/apod/archivepix.html
  24. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  25. https://apod.nasa.gov/apod/lib/aptree.html
  26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  27. https://apod.nasa.gov/apod/calendar/allyears.html
  28. https://apod.nasa.gov/apod.rss
  29. https://apod.nasa.gov/apod/lib/edlinks.html
  30. https://apod.nasa.gov/apod/lib/about_apod.html
  31. http://asterisk.apod.com/discuss_apod.php?date=210201
  32. https://apod.nasa.gov/apod/ap210202.html
  33. http://www.phy.mtu.edu/faculty/Nemiroff.html
  34. http://www.phy.mtu.edu/
  35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  36. http://www.astro.umd.edu/
  37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  38. https://www.nasa.gov/about/highlights/HP_Privacy.html
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. http://www.mtu.edu/