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 March 1
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                               A Hole in Mars
                Image Credit: [3]NASA, [4]JPL, [5]U. Arizona

   Explanation: What created this unusual hole in Mars? [6]The hole was
   discovered by chance in 2011 on images of the dusty slopes of Mars'
   [7]Pavonis Mons volcano taken by the [8]HiRISE instrument aboard the
   robotic [9]Mars Reconnaissance Orbiter currently circling Mars. The
   hole, shown in representative color, appears to be an opening to an
   underground cavern, partly illuminated on the image right. Analysis of
   this and follow-up images revealed the [10]opening to be about 35
   meters across, while the interior [11]shadow angle indicates that the
   underlying cavern is roughly 20 meters deep. Why there is a circular
   crater surrounding this hole remains a topic of [12]speculation, as is
   the full extent of the underlying cavern. [13]Holes such as [14]this
   are of particular interest because their interior caves are relatively
   protected from the harsh surface of [15]Mars, making them relatively
   good candidates to [16]contain Martian life. These pits are therefore
   prime targets for [17]possible future spacecraft, robots, and even
   [18]human interplanetary explorers.

                       Tomorrow's picture: big dolphin
     __________________________________________________________________

      [19]< | [20]Archive | [21]Submissions | [22]Index | [23]Search |
   [24]Calendar | [25]RSS | [26]Education | [27]About APOD | [28]Discuss |
                                    [29]>
     __________________________________________________________________

    Authors & editors: [30]Robert Nemiroff ([31]MTU) & [32]Jerry Bonnell
                                 ([33]UMCP)
          NASA Official: Phillip Newman [34]Specific rights apply.
              [35]NASA Web Privacy Policy and Important Notices
                A service of: [36]ASD at [37]NASA / [38]GSFC
                           & [39]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2003/marshole2r_hirise_2560.jpg
   3. https://www.nasa.gov/
   4. https://www.jpl.nasa.gov/
   5. https://hirise.lpl.arizona.edu/
   6. https://hirise.lpl.arizona.edu/ESP_023531_1840
   7. https://en.wikipedia.org/wiki/Pavonis_Mons
   8. https://en.wikipedia.org/wiki/HiRISE
   9. https://mars.jpl.nasa.gov/mro/mission/overview/
  10. http://en.wikipedia.org/wiki/File:Close-up_of_a_skylight_on_coastal_plain,_with_lava_stalactites_forming_on_the_roof_of_the_tube.jpg
  11. https://apod.nasa.gov/apod/ap110508.html
  12. http://www.lifeinthedoglane.com/wp-content/uploads/2013/03/puppy-head-tilt.jpg
  13. https://apod.nasa.gov/apod/ap070528.html
  14. https://apod.nasa.gov/apod/ap070928.html
  15. https://solarsystem.nasa.gov/planets/mars/overview/
  16. https://science.nasa.gov/science-news/science-at-nasa/2007/21sep_caves
  17. https://www.nasa.gov/feature/ames/braille
  18. https://en.wikipedia.org/wiki/The_Martian_Chronicles
  19. https://apod.nasa.gov/apod/ap200229.html
  20. https://apod.nasa.gov/apod/archivepix.html
  21. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  22. https://apod.nasa.gov/apod/lib/aptree.html
  23. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  24. https://apod.nasa.gov/apod/calendar/allyears.html
  25. https://apod.nasa.gov/apod.rss
  26. https://apod.nasa.gov/apod/lib/edlinks.html
  27. https://apod.nasa.gov/apod/lib/about_apod.html
  28. http://asterisk.apod.com/discuss_apod.php?date=200301
  29. https://apod.nasa.gov/apod/ap200302.html
  30. http://www.phy.mtu.edu/faculty/Nemiroff.html
  31. http://www.phy.mtu.edu/
  32. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  33. http://www.astro.umd.edu/
  34. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  35. https://www.nasa.gov/about/highlights/HP_Privacy.html
  36. https://astrophysics.gsfc.nasa.gov/
  37. https://www.nasa.gov/
  38. https://www.nasa.gov/centers/goddard/
  39. http://www.mtu.edu/