Scientists said Tuesday they have found the best evidence yet of ice volcanoes on Saturn's giant moon Titan. Unlike volcanoes on Earth, such a volcano on Titan may spew ice and hydrocarbons instead of molten lava.
"We finally have some proof that Titan is an active world," said geophysicist Randolph Kirk of the U.S. Geological Survey, who presented the findings.
The latest evidence comes from the international Cassini spacecraft, which spied two peaks over 3,000 feet tall and what looked like old volcanic flows. Researchers said the landforms resembled Mount Etna in Italy or Laki volcano in Iceland.
There's no sign of volcanic activity on Titan, though scientists are keeping watch.
It's not the first time that researchers have suspected Titan may hold icy volcanoes. A previous sighting in 2005 by the Cassini spacecraft of a potential ice volcano turned out to be wrong upon further study.
Kirk, who used 3-D mapping to study Titan's land features, said the evidence was stronger this time around. Results were presented at the American Geophysical Union meeting in San Francisco.
Planetary scientist Jeffrey Kargel of the University of Arizona, who was not involved in the discovery, said the data was compelling. Kargel noted that unless there's a mission to bring back samples, scientists may never know what the flows are made of.
Titan is one of the few bodies in the solar system with a thick atmosphere made up of nitrogen and methane. The source of methane remains a mystery. The existence of volcanoes may help explain how the moon got its smoggy atmosphere.
Launched in 1997, Cassini entered orbit around Saturn in 2004 to study its rings and many moons including its largest, Titan. The mission is a project of NASA, the European Space Agency and the Italian Space Agency.