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.

                                2025 June 21
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                          Two Worlds, Two Analemmas
    Image Credit: (left) [3]Copyright: [4]Tunc Tezel ([5]TWAN) - (right):
                        [6]NASA/JPL/Cornell/ASU/TAMU

   Explanation: [7]Sure, that figure-8 shaped curve you get when you
   [8]mark the position of the Sun in Earth's sky at the same time each
   day over one year is called an analemma. [9]On the left, Earth's
   figure-8 analemma was traced by combining wide-angle digital images
   recorded during the year from December 2011 through December 2012.
   [10]But the shape of an analemma depends on the eccentricity of a
   planet's orbit and the tilt of its axis of rotation, so analemma curves
   [11]can look different for different worlds. [12]Take Mars for example.
   The Red Planet's axial tilt is similar to Earth's, but its orbit around
   [13]the same sun is more eccentric (less circular) than Earth's orbit.
   As seen from the Martian surface, the analemma traced in the right hand
   panel is shaped more like a tear drop. The Mars rover Opportunity
   captured the images used over the Martian year corresponding to Earth
   dates July 2006 to June 2008. Of course, each world's solstice dates
   still lie at the top and bottom of their different analemma curves.
   [14]The last Mars northern summer solstice was May 29, 2025. Our fair
   planet's 2025 northern summer solstice is at [15]June 21, 2:42 UTC.

                Tomorrow's picture: just a bowl of spherules
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    Authors & editors: [27]Robert Nemiroff ([28]MTU) & [29]Jerry Bonnell
                                 ([30]UMCP)
          NASA Official: Amber Straughn [31]Specific rights apply.
            [32]NASA Web Privacy, [33]Accessibility, [34]Notices;
                A service of: [35]ASD at [36]NASA / [37]GSFC,
                         [38]NASA Science Activation
                           & [39]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2506/AnalemmaEarthMars.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://twanight.org/profile/tunc-tezel/
   5. https://twanight.org/
   6. https://www.nasa.gov/
   7. https://apod.nasa.gov/apod/ap250320.html
   8. https://apod.nasa.gov/apod/ap241204.html
   9. https://apod.nasa.gov/apod/ap131014.html
  10. https://analemma.com/other-analemmas.html
  11. https://en.wikipedia.org/wiki/Analemma#Seen_from_other_planets
  12. https://www.planetary.org/articles/a-martian-analemma
  13. https://apod.nasa.gov/apod/ap250615.html
  14. https://www.planetary.org/articles/mars-calendar
  15. https://earthsky.org/astronomy-essentials/everything-you-need-to-know-june-solstice/
  16. https://apod.nasa.gov/apod/ap250620.html
  17. https://apod.nasa.gov/apod/archivepix.html
  18. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  19. https://apod.nasa.gov/apod/lib/aptree.html
  20. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  21. https://apod.nasa.gov/apod/calendar/allyears.html
  22. https://apod.com/feed.rss
  23. https://apod.nasa.gov/apod/lib/edlinks.html
  24. https://apod.nasa.gov/apod/lib/about_apod.html
  25. https://asterisk.apod.com/discuss_apod.php?date=250621
  26. https://apod.nasa.gov/apod/ap250622.html
  27. http://www.phy.mtu.edu/faculty/Nemiroff.html
  28. http://www.phy.mtu.edu/
  29. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  30. http://www.astro.umd.edu/
  31. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  32. https://www.nasa.gov/about/highlights/HP_Privacy.html
  33. https://www.nasa.gov/general/accessibility/
  34. https://www.nasa.gov/privacy/
  35. https://astrophysics.gsfc.nasa.gov/
  36. https://www.nasa.gov/
  37. https://www.nasa.gov/centers/goddard/
  38. https://science.nasa.gov/learners
  39. http://www.mtu.edu/