These two gray-scale images from NASA’s Space Shuttle show part of the Nile River, near the Fourth Cataract in Sudan. (Photo : NASA/JPL-Caltech )
On Titan, Saturn's moon, a Nile-like river filled with the liquid hydrocarbons ethane and methane stretches 250 miles long. Captured by NASA's Cassini orbiter, images of the natural formation reached earth on September 26.
In a press release, Steve Wall of NASA's Jet Propulsion Laboratory notes that "Titan is the only place we've found besides Earth that has liquid in continuous movement on its surface. 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."
Cassini scientist Nicholas Altobelli explains that the this "world in motion...was first hinted at from the images of channels and gullies seen by ESA's Huygens probe as it descended to the moon's surface in 2005." The Cassini mission itself originally launched in 1997.
"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 the same Titan sea," says Cassini team member Jani Radebaugh. "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
NASA notes that the photograph displays the northern pole region of the moon.