                        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.

                                2021 August 5

                              Tycho and Clavius
            Image Credit & Copyright: Eduardo Schaberger Poupeau

   Explanation: South is up in this detailed telescopic view across the
   Moon's rugged southern highlands. Captured on July 20, the lunar
   landscape features the Moon's young and old, the large craters Tycho
   and Clavius. About 100 million years young, Tycho is the sharp-walled
   85 kilometer diameter crater near center, its 2 kilometer tall central
   peak in bright sunlight and dark shadow. Debris ejected during the
   impact that created Tycho still make it the stand out lunar crater when
   the Moon is near full, producing a highly visible radiating system of
   light streaks, bright rays that extend across much of the lunar near
   side. In fact, some of the material collected at the Apollo 17 landing
   site, about 2,000 kilometers away, likely originated from the Tycho
   impact. One of the oldest and largest craters on the Moon's near side,
   225 kilometer diameter Clavius is due south (above) of Tycho. Clavius
   crater's own ray system resulting from its original impact event would
   have faded long ago. The old crater's worn walls and smooth floor are
   now overlayed by smaller craters from impacts that occurred after
   Clavius was formed. Observations by the Stratospheric Observatory for
   Infrared Astronomy (SOFIA) published in 2020 found water at Clavius. Of
   course both young Tycho and old Clavius craters are lunar locations in
   the science fiction epic 2001: A Space Odyssey.

                     Tomorrow's picture: stars and dust
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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