Posted: Sun, Jul 31, 2005, 9:21 AM ET (1321 GMT)
Enceladus, a small, icy moon of Saturn, may surprisingly be volcanically active, scientists analyzing data from the Cassini mission announced Friday. Cassini detected a large cloud of water vapor surrounding the moon when it flew past the icy world on July 14. Because Enceladus is so small — 500 kilometers across — the only way the moon could retain that cloud of vapor for any length of time is if the moon replenishes the cloud with some kind of volcanic activity. Cassini also found that the south pole of Enceladus is warmer than other regions of the moon's surface, presumably because of some kind of internal heating. Scientists are puzzled how a moon as small as Enceladus could generate enough internal heat to drive volcanic activity and why it is concentrated in a single region.

Related Links:

•  AP article
•  NASA press release