                        Astronomy Picture of the Day

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                    written by a professional astronomer.

                                2022 July 16

                          Tycho and Clavius at Dawn
            Image Credit & Copyright: Eduardo Schaberger Poupeau

   Explanation: South is up in this dramatic telescopic view of the lunar
   terminator and the Moon's rugged southern highlands. The lunar
   landscape was captured on July 7 with the moon at its first quarter
   phase. The Sun shines at a low angle from the right as dawn comes to
   the region's young and old craters Tycho and Clavius. About 100 million
   years young, Tycho is the sharp-walled 85 kilometer diameter crater
   below and left of center. Its 2 kilometer tall central peak and far
   crater wall reflect bright sunlight, Its smooth floor lies in dark
   shadow. Debris ejected during the impact that created Tycho make it the
   stand out lunar crater when the Moon is near full though. They produce
   a highly visible radiating system of light streaks or 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 newer smaller craters
   from impacts that occurred after Clavius was formed. Reaching above the
   older crater, tops of the newer crater walls reflect this dawn's early
   light to create narrow shining arcs within a shadowed Clavius.

                   Tomorrow's picture: Europa and Jupiter
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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.

