Crescent moon Rhea
With a diameter of 1528 kilometres across, Rhea is Saturn's second largest moon.
The US Voyager spacecraft found that, like Dione, Rhea has one of its hemispheres covered with bright, wispy streaks which may be water frost.
This view from the NASA/ESA/ASI Cassini-Huygens spacecraft shows a heavily cratered surface, and thus it is most likely ancient. Many of the craters visible here have central peaks.
Cassini soon will look for clues to help unlock the moon's geological history. The spacecraft is due to fly by Rhea at a distance of only 500 kilometres on 6 November 2005.
The Cassini-Huygens mission is a co-operative project of NASA, ESA and ASI, the Italian space agency.
Credits: NASA/JPL/Space Science Institute
