Sen— What appears to be a miniature 'out of this world' version of the Nile River has been spotted on Saturn's largest moon Titan. The river valley was discovered by the Cassini spacecraft.
It's the first time images have shown a river system so vast, and in such resolution, beyond Earth. It stretches more than 400km from its ‘headwaters’ to a large sea. Scientists say they believe the river is filled with liquid, that is because on the high resolution radar images it appears dark along its entire extent, indicating a smooth surface.
“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” suggests Jani Radebaugh, a Cassini radar team associate at Brigham Young University, USA. “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.”
Titan, is the only natural satellite known to have a dense atmosphere, as well as being the only other world we know of that has stable liquid on its surface. On Titan there is also an equivalent to our water cycle, however the cycle involves hydrocarbons such as ethane and methane and happens at a much lower temperature. It's also thought that the climate on Titan, which includes wind and rain, creates surface features similar to Earth. This is supported by images from Cassini’s visible-light cameras, which in late 2010 showed regions that darkened after recent rainfall.
“This radar-imaged river by Cassini provides another fantastic snapshot of a world in motion, which 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,” adds Nicolas Altobelli, ESA’s Cassini Project Scientist.
The liquid is not water, and in 2008 the visual and infrared mapping spectrometer on Cassini confirmed liquid ethane at a lake in Titan’s southern hemisphere - this is known as Ontario Lacus.
Cassini, is part of the Cassini–Huygens mission which involves NASA, ESA and ASI (The Italian Space Agency). It was launched in October 1997. The Huygens probe landed on Titan in 2005, while the Cassini spacecraft continues to orbit Saturn.