Astronomy Picture of the Day

    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

                               A Hole in Mars
                     Image Credit: NASA, JPL, U. Arizona

   Explanation: What created this unusual hole in Mars? The hole was
   discovered by chance in 2011 on images of the dusty slopes of Mars'
   Pavonis Mons volcano taken by the HiRISE instrument aboard the robotic
   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 opening to be about 35 meters across,
   while the interior 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 speculation, as is the full extent of the
   underlying cavern. Holes such as this are of particular interest
   because their interior caves are relatively protected from the harsh
   surface of Mars, making them relatively good candidates to contain
   Martian life. These pits are therefore prime targets for possible
   future spacecraft, robots, and even human interplanetary explorers.

                       Tomorrow's picture: big dolphin
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.

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