Titan's the only other world in the Solar System with rivers and rain. It's a shame we know so little about it.>This image, taken with the radar on the Cassini spacecraft, shows just how similar the features in Titan’s surface are to Earth’s landforms.>Aside from Earth, Titan is the only other body where we have found evidence of active erosion on a large scale. There are seas, lakes and rivers filled with liquid hydrocarbons – mainly methane and some ethane – that etch the moon’s surface, in much the same way water erodes Earth’s.>A striking example is Vid Flumina, the Nile-like, branching river system visible on the upper-left quadrant of the image. The river, in the moon’s north polar region, flows into Ligeia Mare, a methane-rich sea that appears as a dark patch on the right side of the image.>Researchers in Italy and the US analysed Cassini radar observations from May 2013 and recently revealed that the narrow channels that branch off Vid Flumina are deep, steep-sided canyons filled with flowing hydrocarbons.>The channels are a little less than a kilometre wide, up to 570 m deep and with slopes steeper than 40º. This suggests they have been sculpted by liquid methane, flowing into the main Vid Flumina river, that has persistently eroded the canyon walls – a geological process reminiscent of the carving of river gorges on our planet.>The study is the first direct evidence of deeply entrenched, methane-flooded channels on Titan. Finding out how they formed provides insights into the moon’s origin and evolution and could help understand similar geological processes on Earth.>The Cassini–Huygens radar team is hoping to observe the Ligeia Mare and Vid Flumina region again in April 2017, during Cassini’s final approach to Titan. The mission is a cooperation between NASA, ESA and Italy’s ASI space agency.