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.

                               2020 January 10
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                         Nacreous Clouds over Sweden
      Image Credit & [3]Copyright: P-M Hedén ([4]Clear Skies, [5]TWAN)

   Explanation: Vivid and lustrous, wafting iridescent waves of color
   filled this mountain and skyscape near Tanndalen, Sweden on January 3.
   [6]Known as nacreous clouds or mother-of-pearl clouds, they are rare.
   This northern winter season they have been making [7]unforgettable
   appearances at high latitudes, though. A type of [8]polar stratospheric
   cloud, they form when unusually cold temperatures in the usually
   cloudless [9]lower stratosphere form ice crystals. Still sunlit at
   altitudes of around 15 to 25 kilometers the clouds can diffract
   sunlight after sunset and before the dawn.

                       Tomorrow's picture: and beyond
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    Authors & editors: [21]Robert Nemiroff ([22]MTU) & [23]Jerry Bonnell
                                 ([24]UMCP)
          NASA Official: Phillip Newman [25]Specific rights apply.
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                A service of: [27]ASD at [28]NASA / [29]GSFC
                           & [30]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2001/NacreousPMHeden.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. http://www.clearskies.se/
   5. http://www.twanight.org/
   6. https://www.atoptics.co.uk/highsky/nacr1.htm
   7. https://ui.adsabs.harvard.edu/abs/2018BAMS...99.1377P/abstract
   8. https://www.nasa.gov/multimedia/imagegallery/image_feature_680.html
   9. https://www.atoptics.co.uk/highsky/htrop.htm
  10. https://apod.nasa.gov/apod/ap200109.html
  11. https://apod.nasa.gov/apod/archivepix.html
  12. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  13. https://apod.nasa.gov/apod/lib/aptree.html
  14. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  15. https://apod.nasa.gov/apod/calendar/allyears.html
  16. https://apod.nasa.gov/apod.rss
  17. https://apod.nasa.gov/apod/lib/edlinks.html
  18. https://apod.nasa.gov/apod/lib/about_apod.html
  19. http://asterisk.apod.com/discuss_apod.php?date=200110
  20. https://apod.nasa.gov/apod/ap200111.html
  21. http://www.phy.mtu.edu/faculty/Nemiroff.html
  22. http://www.phy.mtu.edu/
  23. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  24. http://www.astro.umd.edu/
  25. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  26. https://www.nasa.gov/about/highlights/HP_Privacy.html
  27. https://astrophysics.gsfc.nasa.gov/
  28. https://www.nasa.gov/
  29. https://www.nasa.gov/centers/goddard/
  30. http://www.mtu.edu/