NASA scientists have spotted a miniature version of Earth's Nile River on Saturn's moon Titan. The river on Titan stretches more than 200 miles (400 kilometers) from its "headwaters" to a larger sea.
Images taken by NASA's Cassini mission for the first time have revealed a river system that is vast and in high resolution, NASA said.
Scientists believe that the river valley, situated in Titan's North Polar Region, is filled with liquid hydrocarbons because it appears dark along its entire length, indicating a smooth surface.
"Though there are some short, local meanders, the relative straightness of the river valley suggests it follows the trace of at least one fault, similar to other large rivers running into the southern margin of this same Titan sea," said Jani Radebaugh, a Cassini radar team associate at Brigham Young University, Provo, Utah.
"Such faults - fractures in Titan's bedrock -- may not imply plate tectonics, like on Earth, but still lead to the opening of basins and perhaps to the formation of the giant seas themselves," Radebaugh added.
Apart from Earth, Titan is the only other body in the solar system that has stable liquid on its surface. Earth's hydrologic cycle relies on water, but Titan's equivalent cycle is composed of hydrocarbons such as ethane and methane.
"Titan is the only place we've found besides Earth that has a liquid in continuous movement on its surface," said Steve Wall, the radar deputy team lead, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"This picture gives us a snapshot of a world in motion. Rain falls, and rivers move that rain to lakes and seas, where evaporation starts the cycle all over again. On Earth, the liquid is water; on Titan, it's methane; but on both it affects most everything that happens," he added.