Astronomy Picture of the Day
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November 4, 1995
Neptune's Moon Proteus
Proteus is the second largest moon of
Neptune behind the mysterious
Proteus was discovered only in 1982 by the Voyager 2 spacecraft. This is
unusual since Neptune has a smaller moon - Nereid - which was discovered
33 years earlier from Earth. The reason
Proteus was not discovered sooner
is that its surface is very dark and it orbits much closer to Neptune.
Proteus has an odd box-like shape and were it even slightly more
massive, its own gravity would cause it to reform itself into a sphere.
Tomorrow's picture: The Watchers
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