Astronomy Picture of the Day
Discover the cosmos! Each day we feature a different image or photograph
of our fascinating universe, along with a brief explanation written by a
November 24, 1995
Saturn's Moon Tethys
Calvin J. Hamilton
Tethys is one of the larger and closer moons of
Saturn. It was visited
by both Voyager spacecraft - Voyager 1 in November 1980 and by Voyager 2 in
Tethys is now known to be composed almost completely of water
ice. Tethys shows a large impact crater that nearly circles the planet.
That the impact that caused this crater did not disrupt the moon is taken
as evidence that Tethys was not completely frozen in its past.
Tethys has two moons named
Calypso that orbit just ahead
of it and behind it. Tethys was originally discovered in 1684 by
Tomorrow's picture: Saturn's Cleanest Moon: Enceladus
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