spacetoday.net: Hot spot caused Enceladus to roll over

Posted: Mon, Jun 5, 2006, 1:47 PM ET (1747 GMT)
Enceladus seen by Cassini in July 2005 (NASA/JPL)

A hot spot within Saturn's moon Enceladus may have caused the moon to "roll over" and put the hot spot at its south pole, scientists said last week. In a paper published in the journal Nature, researchers said that the formation of a hot blob, or diapir, of lower-density material below the moon's icy surface may have caused the moon to realign its spin axis so that it passed through the diapir, in order to preserve its spin stability. Evidence for the diapir comes from Cassini observations of the Moon, which revealed anomalously warm temperatures at the south pole as well as evidence for water vapor plumes. The heat source creating the diapir is believed to be tidal heating caused by the moon's eccentric orbit around Saturn.