Astronomy Picture of the Day
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October 14, 1995
Rhea: Saturn's Second Largest Moon
Copyright Calvin J. Hamilton
Rhea is the second largest moon of
and the largest without an atmosphere. It is composed mostly of water
ice, but has a small rocky core.
rotation and orbit are locked together (just like Earth's Moon)
so that one side always faces Saturn. A consequence of this is that one
side always leads the other. Rhea's leading surface is much more heavily
cratered than its trailing surface. The above photograph was taken with the
Voyager 1 spacecraft in 1980.
Tomorrow's picture: Iapetus: Saturn's Disappearing Moon
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