The Cassini Solstice mission has discovered what appears to be a miniature version* of the Nile River on Saturn’s largest moon, Titan. The 400 kilometer (250 mile) long feature — from ‘headwaters’ to a large sea — is the longest extraterrestrial river ever to be discovered and imaged to such high resolution.
Using Cassini’s radar imaging instruments, mission scientists were able to deduce that the feature is indeed a river as the dark, smooth surface within the meanders and channel suggest the presence of a liquid.
Titan is known to have vast lakes — the only other body in the solar system, apart from Earth, to possess a cycle of liquids on its surface. However, the thick Titan atmosphere is a frigid one, meaning liquid water couldn’t possibly flow. The liquids on Titan are therefore composed of hydrocarbons such as methane and ethane.
Interestingly, using this observation of a vast river system on Titan reveals not only that rivers flow, it could also trace the path of fault lines on the Saturnian moon, suggestive of fractures in Titan’s bedrock.
“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, Cassini radar team associate at Brigham Young University.