Lake on Saturn moon has Earth counterpart

PARIS, April 19 (UPI) -- An "ephemeral" lake on Saturn's moon Titan -- a large, shallow depression that sometimes fills with liquid -- has a counterpart on Earth, scientists say.

Landforms and the climatic conditions in the region of Titan are similar to those of semi-arid regions on Earth such as the salt pans of southern Africa, including the Etosha Pan in Namibia, the European Space Agency reported Thursday.

Unlike its Earthly counterparts, however, Ontario Lacus on Titan is filled with liquid hydrocarbons, not water, researchers said.

It only a few yards deep at most, located in an extremely shallow depression in a flat sedimentary basin surrounded by small mountain ranges, they said.

Ontario Lacus was previously thought to be permanently filled with liquid methane, ethane and propane, but new observations by the Cassini orbiter suggest otherwise, scientists said.

Cassini's instruments show some parts of the lake's bed are exposed from time to time, they said.

This is similar to ephemeral lakes on Earth, they said, where the lake bed fills with a shallow layer of water as an underground aquifer rises during the rainy season, before evaporating to leave sediments like tide marks showing the previous extent of the water.

"These results emphasize the importance of comparative planetology in modern planetary sciences: finding familiar geological features on alien worlds like Titan allows us to test the theories explaining their formation," Nicolas Altobelli, ESA's Cassini–Huygens project scientist, said.