                        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.

                                 2022 July 3

                         Phobos: Doomed Moon of Mars
              Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA

   Explanation: This moon is doomed. Mars, the red planet named for the
   Roman god of war, has two tiny moons, Phobos and Deimos, whose names
   are derived from the Greek for Fear and Panic. These martian moons may
   well be captured asteroids originating in the main asteroid belt
   between Mars and Jupiter or perhaps from even more distant reaches of
   our Solar System. The larger moon, Phobos, is indeed seen to be a
   cratered, asteroid-like object in this stunning color image from the
   robotic Mars Reconnaissance Orbiter, with objects as small as 10 meters
   visible. But Phobos orbits so close to Mars - about 5,800 kilometers
   above the surface compared to 400,000 kilometers for our Moon - that
   gravitational tidal forces are dragging it down. In perhaps 50 million
   years, Phobos is expected to disintegrate into a ring of debris.

                  Tomorrow's picture: strawberry supermoon
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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.

