The first-ever image of a massive river system on another world

Illustration for article titled The first-ever image of a massive river system on another world

This image was taken by the space probe Cassini, and shows what appears to be a massive river system on Saturn's moon Titan. The European Space Agency reports that it flows 400 km across the cloudy moon's surface, where it meets a large sea. This is most likely a river made of liquid ethane or methane, not water. Though previous Cassini observations of Titan revealed what appeared to be seasonal lakes there, this is the first confirmation we've had that the moon also has long, meandering rivers that form tributaries just like water does on Earth.

Illustration for article titled The first-ever image of a massive river system on another world

Here is the full image. Click to enlarge.

According to the ESA:

Scientists deduce that the river is filled with liquid because it appears dark along its entire extent in the high-resolution radar image, 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," says Jani Radebaugh, a Cassini radar team associate at Brigham Young University, USA.

"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."

Titan is the only other world we know of that has stable liquid on its surface. While Earth's hydrologic cycle relies on water, Titan's equivalent cycle involves hydrocarbons such as ethane and methane.

Images from Cassini's visible-light cameras in late 2010 revealed regions that darkened after recent rainfall.


Scientists have speculated that the fluid in Titan's waterways might be viscous, like oil or even tar.

Learn more, and see a higher resolution version of the image at ESA. (Spotted on Classic Detritus!)

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Question: why is it so hard to get high res color photos of other planets/moons in our solar system?

I mean, we have photos of galaxies billions of light years away. I get that they're obviously orders of magnitude larger than anything in our solar system, and that they're really low res pictures too. But we're talking about celestial bodies that we can send satellites too, so why are the photos such poor quality? I can go on Google Maps right now and see satellite photos showing my car in my drive way. It seems like a satellite NASA sends would be at least as capable.