Ancient rivers suggest Mars was much wetter than we thought

Thousands of kilometres of ancient riverbeds have been discovered in the southern highlands of Mars, suggesting the red planet was once a far wetter world than scientists thought.

- Ian Sample

Researchers found geological traces of nearly 16,000km (9,940 miles) of ancient watercourses, believed to be more than 3bn years old, in high resolution images of the rugged landscape captured by Mars orbiters.

While some of the riverbeds are relatively short, others form networks that stretch for more than 100 miles. The widespread rivers were probably replenished by regular rain or snowfall, researchers said.

"Water has been found on Mars countless times before, but what's really interesting here is that this is an area where for a long time we've thought there wasn't any evidence for water," said Adam Losekoot, a PhD student at the Open University.