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.
In comparison, the Nile River in Egypt is 6,650 kilometers (4,132 miles) long.
Using Cassini’s radar imaging instruments, the 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 seas -- 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," Discovery News quoted Jani Radebaugh, Cassini radar team associate at Brigham Young University, as saying.
"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 stated.
Cassini has previously confirmed the presence of large masses of liquids including Ontario Lacus, a lake in the southern hemisphere composed of liquid ethane. Rainfall has also been detected in the atmosphere, hinting not of a hydrological cycle (which gives us water rain, rivers and oceans on Earth), but of a methane cycle.