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                        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 May 24
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                 Valles Marineris: The Grand Canyon of Mars
              Image Credit: [3]NASA, [4]USGS, [5]Viking Project

   Explanation: The largest canyon in the [6]Solar System cuts a wide
   swath across the face of [7]Mars. Named [8]Valles Marineris, the grand
   valley extends over 3,000 kilometers long, spans as much as 600
   kilometers across, and delves as much as 8 kilometers deep. By
   comparison, the [9]Earth's Grand Canyon in Arizona, USA is 800
   kilometers long, 30 kilometers across, and 1.8 kilometers deep. The
   origin of the [10]Valles Marineris remains unknown, although a leading
   hypothesis holds that it started as a [11]crack billions of years ago
   as the planet cooled. Several geologic processes have been identified
   in [12]the canyon. The [13]featured mosaic was [14]created from over
   100 images of [15]Mars taken by [16]Viking Orbiters in the 1970s.

                  Tomorrow's picture: interstellar monster
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    Authors & editors: [28]Robert Nemiroff ([29]MTU) & [30]Jerry Bonnell
                                 ([31]UMCP)
          NASA Official: Phillip Newman [32]Specific rights apply.
              [33]NASA Web Privacy Policy and Important Notices
                A service of: [34]ASD at [35]NASA / [36]GSFC
                           & [37]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2005/marsglobe_viking_1552.jpg
   3. https://www.nasa.gov/
   4. https://www.usgs.gov/
   5. https://nssdc.gsfc.nasa.gov/planetary/viking.html
   6. https://space.jpl.nasa.gov/
   7. https://solarsystem.nasa.gov/planets/mars/overview/
   8. http://www.youtube.com/watch?v=crsqzZNUXsY
   9. https://en.wikipedia.org/wiki/Grand_Canyon
  10. https://en.wikipedia.org/wiki/Valles_Marineris
  11. https://apod.nasa.gov/apod/ap980310.html
  12. https://mars.nasa.gov/gallery/atlas/valles-marineris.html
  13. http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mars.html
  14. http://nssdc.gsfc.nasa.gov/photo_gallery/caption/marsglobe1.txt
  15. http://mars.jpl.nasa.gov/allaboutmars/facts/
  16. http://pds.jpl.nasa.gov/planets/welcome/viking.htm
  17. https://apod.nasa.gov/apod/ap200523.html
  18. https://apod.nasa.gov/apod/archivepix.html
  19. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  20. https://apod.nasa.gov/apod/lib/aptree.html
  21. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  22. https://apod.nasa.gov/apod/calendar/allyears.html
  23. https://apod.nasa.gov/apod.rss
  24. https://apod.nasa.gov/apod/lib/edlinks.html
  25. https://apod.nasa.gov/apod/lib/about_apod.html
  26. http://asterisk.apod.com/discuss_apod.php?date=200524
  27. https://apod.nasa.gov/apod/ap200525.html
  28. http://www.phy.mtu.edu/faculty/Nemiroff.html
  29. http://www.phy.mtu.edu/
  30. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  31. http://www.astro.umd.edu/
  32. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  33. https://www.nasa.gov/about/highlights/HP_Privacy.html
  34. https://astrophysics.gsfc.nasa.gov/
  35. https://www.nasa.gov/
  36. https://www.nasa.gov/centers/goddard/
  37. http://www.mtu.edu/