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 September 12
     [2]The picture shows a dramatic spiral-shaped aurora over Iceland.
          Please see the explanation for more detailed information.

                        A Spiral Aurora over Iceland
                 Image Credit & Copyright: [3]Davide Necchi

   Explanation: What's happened to the sky? [4]Aurora! Captured in 2015,
   [5]this aurora was noted by [6]Icelanders for its great brightness and
   quick development. The aurora resulted from a solar storm, with high
   energy particles bursting out from the Sun and through a [7]crack in
   Earth's protective [8]magnetosphere a few days later. Although a
   [9]spiral pattern can be discerned, [10]creative [11]humans might
   imagine the complex glow as an atmospheric [12]apparition of any number
   [13]of [14]common [15]icons. In the foreground of the featured image is
   the [16]Ölfusá River while the lights illuminate a bridge in
   [17]Selfoss City. Just beyond the low clouds is a nearly full Moon. The
   [18]liveliness of the Sun -- and likely the [19]resulting auroras on
   Earth -- is slowly increasing as the Sun emerges from a [20]Solar
   minimum, a historically quiet period in its 11-year cycle.

                   Tomorrow's picture: night sky reflected
     __________________________________________________________________

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    Authors & editors: [32]Robert Nemiroff ([33]MTU) & [34]Jerry Bonnell
                                 ([35]UMCP)
          NASA Official: Phillip Newman [36]Specific rights apply.
              [37]NASA Web Privacy Policy and Important Notices
                A service of: [38]ASD at [39]NASA / [40]GSFC
                           & [41]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2109/AuroraIceland_Necchi_1280.jpg
   3. https://www.davnec.eu/a-proposito-del-necchi/
   4. http://www.nasa.gov/mission_pages/sunearth/news/gallery/aurora-index.html
   5. https://www.davnec.eu/a-spiral-aurora-over-iceland/
   6. https://en.wikipedia.org/wiki/Iceland
   7. http://science.nasa.gov/science-news/science-at-nasa/2003/03dec_magneticcracks/
   8. http://science.nasa.gov/heliophysics/focus-areas/magnetosphere-ionosphere/
   9. https://mathshistory.st-andrews.ac.uk/Curves/Hyperbolic/curvesapplet/
  10. https://www.aaha.org/contentassets/f14651384f2f4f2a8def2d3595524fee/imageodxx9.png
  11. https://apod.nasa.gov/apod/ap190818.html
  12. https://en.wikipedia.org/wiki/Pareidolia
  13. https://apod.nasa.gov/apod/ap140429.html
  14. https://apod.nasa.gov/apod/ap120124.html
  15. https://apod.nasa.gov/apod/ap121003.html
  16. https://www.youtube.com/watch?v=Yvz6Tzm9Vds
  17. https://www.youtube.com/watch?v=y00StWk1p2g
  18. https://apod.nasa.gov/apod/ap141022.html
  19. https://apod.nasa.gov/apod/ap201109.html
  20. https://en.wikipedia.org/wiki/Solar_minimum
  21. https://apod.nasa.gov/apod/ap210911.html
  22. https://apod.nasa.gov/apod/archivepix.html
  23. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  24. https://apod.nasa.gov/apod/lib/aptree.html
  25. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  26. https://apod.nasa.gov/apod/calendar/allyears.html
  27. https://apod.nasa.gov/apod.rss
  28. https://apod.nasa.gov/apod/lib/edlinks.html
  29. https://apod.nasa.gov/apod/lib/about_apod.html
  30. http://asterisk.apod.com/discuss_apod.php?date=210912
  31. https://apod.nasa.gov/apod/ap210913.html
  32. http://www.phy.mtu.edu/faculty/Nemiroff.html
  33. http://www.phy.mtu.edu/
  34. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  35. http://www.astro.umd.edu/
  36. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  37. https://www.nasa.gov/about/highlights/HP_Privacy.html
  38. https://astrophysics.gsfc.nasa.gov/
  39. https://www.nasa.gov/
  40. https://www.nasa.gov/centers/goddard/
  41. http://www.mtu.edu/