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.

                               2026 February 1
   [2]Several craters are visible on a tan surface. The largest crater, on
   the right, has internal markings that make it look like a winking face
   with a smile. Please see the explanation for more detailed information.

                      Galle: Happy Face Crater on Mars
                   Image Credit: [3]NASA, [4]MGS, [5]MSSS

   Explanation: [6]Mars has put on a happy face. The Martian crater
   [7]Galle is famous because it has internal markings that make it look
   like a face that is both [8]smiling and winking. These markings were
   [9]originally discovered in the 1970s in pictures taken by the
   [10]Viking Orbiter. The [11]Mars Global Surveyor (MGS) spacecraft that
   orbited [12]Mars from 1996 to 2006 captured the [13]featured picture.
   Happy Face Crater and its iconic features were formed by chance
   billions of years ago when a [14]city-sized asteroid slammed into the
   Martian surface. All rocky planets and moons in [15]our Solar System
   show [16]impact craters, with the highest number of craters found on
   [17]Earth's Moon and the planet [18]Mercury. [19]Earth and [20]Venus
   would show the most, though, were it not for weather and [21]erosion.

      Sky Surprise: [22]What picture did APOD feature on your birthday?
                                (after 1995)
                        Tomorrow's picture: fast gas
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    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Amber Straughn [38]Specific rights apply.
            [39]NASA Web Privacy, [40]Accessibility, [41]Notices;
                A service of: [42]ASD at [43]NASA / [44]GSFC,
                         [45]NASA Science Activation
                           & [46]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2602/MarsHappyFace_mgs_525.jpg
   3. https://www.nasa.gov/
   4. https://science.nasa.gov/mission/mars-global-surveyor/
   5. https://www.msss.com/
   6. https://science.nasa.gov/mars/
   7. https://en.wikipedia.org/wiki/Galle_(Martian_crater)
   8. https://en.wikipedia.org/wiki/Smiley
   9. https://i.ytimg.com/vi/ckX_jbdhGpk/hq720.jpg
  10. https://science.nasa.gov/mission/viking/
  11. https://science.nasa.gov/mission/mars-global-surveyor/
  12. https://apod.nasa.gov/apod/ap030422.html
  13. https://science.nasa.gov/photojournal/happy-face-crater-greets-mgs-at-the-start-of-the-mapping/
  14. https://apod.nasa.gov/apod/ap090607.html
  15. https://science.nasa.gov/solar-system/solar-system-facts/
  16. https://www.lpi.usra.edu/education/explore/shaping_the_planets/impact-cratering/
  17. https://apod.nasa.gov/apod/ap010428.html
  18. https://apod.nasa.gov/apod/ap960912.html
  19. https://en.wikipedia.org/wiki/Meteor_Crater
  20. https://apod.nasa.gov/apod/ap250511.html
  21. https://www.earthdata.nasa.gov/topics/land-surface/erosion-sedimentation
  22. https://apod.nasa.gov/apod/calendar/allyears.html
  23. https://apod.nasa.gov/apod/ap260131.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.com/feed.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. https://asterisk.apod.com/discuss_apod.php?date=260201
  33. https://apod.nasa.gov/apod/ap260202.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://www.nasa.gov/general/accessibility/
  41. https://www.nasa.gov/privacy/
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. https://science.nasa.gov/learners
  46. http://www.mtu.edu/