Tethys is one of the larger and closer moons of Saturn.
The Cassini spacecraft now orbiting
passed near the
at the end of October,
capturing the most detailed images since the
in the early 1980s.
is composed almost completely of water ice and shows a large impact crater that nearly circles the moon. Because this crater did not disrupt the moon,
is hypothesized to be at least partly liquid in its past.
Two smaller moons,
Calypso, orbit Saturn just ahead of and behind Tethys.
Giovanni Cassini discovered Tethys in 1684.
The Cassini spacecraft is scheduled for a close fly-by of
Tethys in September 2005.