Earlier this week the Cassini space probe found evidence that Saturn' moon Titan may have ice volcanoes:
Two regions of Titan have been seen recently, by the Cassini spacecraft, to undergo clear changes in brightness.
This activity, and radar images hinting at flow-like structures, suggest the presence of volcanoes, scientists say.
Rather than erupting molten rock, Titan's "cryovolcanoes" are thought to ooze a slurry made of water ice, ammonia and methane.
There are suggestions that these frigid lava flows could be as much as 200m thick.
"Cryovolcanism is a process that many people have modelled in theory and shown to be viable in the outer Solar System on an object of Titan's size," said Bob Nelson from the US space agency Nasa's Jet Propulsion Laboratory.