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.

                               2024 January 13
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                              Circling the Sun
               Image Credit & [3]Copyright: [4]Radoslav Zboran

   Explanation: [5]Earth's orbit around the Sun is not a circle, it's an
   ellipse. The point along its elliptical orbit where our fair planet is
   [6]closest to the Sun is called perihelion. This year, perihelion was
   on January 2 at 01:00 UTC, with the Earth about 3 million [7]miles
   closer to the Sun than it was at aphelion (last July 6), the farthest
   point in its elliptical orbit. Of course, distance from the Sun
   [8]doesn't determine the seasons, and it doesn't the determine size of
   Sun halos. [9]Easier to see with the Sun hidden behind a tall tree
   trunk, this beautiful ice halo forms a 22 degree-wide circle around the
   Sun, recorded while strolling through the countryside near Heroldstatt,
   Germany. The Sun halo's 22 degree angular diameter is [10]determined by
   the six-sided geometry of water ice crystals drifting high in planet
   Earth's atmosphere.

                    Tomorrow's picture: there be dragons
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    Authors & editors: [22]Robert Nemiroff ([23]MTU) & [24]Jerry Bonnell
                                 ([25]UMCP)
          NASA Official: Ryan Smallcomb [26]Specific rights apply.
              [27]NASA Web Privacy Policy and Important Notices
                A service of: [28]ASD at [29]NASA / [30]GSFC,
                         [31]NASA Science Activation
                           & [32]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2401/22halo_Zboran.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.instagram.com/zboran.r/?igsh=YTQwZjQ0NmI0OA==
   5. https://earthsky.org/tonight/earth-comes-closest-to-sun-every-year-in-early-january/
   6. https://blogs.nasa.gov/parkersolarprobe/2024/01/08/nasas-parker-solar-probe-completes-18th-close-approach-to-the-sun/
   7. https://apod.nasa.gov/apod/ap201003.html
   8. https://earthsky.org/astronomy-essentials/december-solstice-january-perihelion-related/
   9. https://apod.nasa.gov/apod/ap231014.html
  10. https://atoptics.co.uk/blog/22-halo-formation/
  11. https://apod.nasa.gov/apod/ap240112.html
  12. https://apod.nasa.gov/apod/archivepix.html
  13. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  14. https://apod.nasa.gov/apod/lib/aptree.html
  15. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  16. https://apod.nasa.gov/apod/calendar/allyears.html
  17. https://apod.nasa.gov/apod.rss
  18. https://apod.nasa.gov/apod/lib/edlinks.html
  19. https://apod.nasa.gov/apod/lib/about_apod.html
  20. http://asterisk.apod.com/discuss_apod.php?date=240113
  21. https://apod.nasa.gov/apod/ap240114.html
  22. http://www.phy.mtu.edu/faculty/Nemiroff.html
  23. http://www.phy.mtu.edu/
  24. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  25. http://www.astro.umd.edu/
  26. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  27. https://www.nasa.gov/about/highlights/HP_Privacy.html
  28. https://astrophysics.gsfc.nasa.gov/
  29. https://www.nasa.gov/
  30. https://www.nasa.gov/centers/goddard/
  31. https://science.nasa.gov/learners
  32. http://www.mtu.edu/