Mars used to have big rivers for billions of years

A new study suggests rivers have flown on Mars for much longer than previously expected, and that they were also quite big. Space.com reports new evidence suggests Mars had rivers until about 1 billion years ago, and that these waterways were wider on average than those on Earth. The planet had multiple wet periods in its history, and the waterways were distributed widely around the planet.

The team's work suggests that Martian rivers flowed intermittently but intensely over much of the planet's 4.5-billion-year history, driven by precipitation-fed runoff. The rivers' impressive width — in many cases, more than twice that of comparable Earth catchments — is a testament to that intensity.

It's unclear how much water Martian rivers carried, because their depth is hard to estimate. Determining depth generally requires up-close analysis of riverbed rocks and pebbles, Kite said, and such work has only been done in a few locations on Mars, such as Gale Crater, which NASA's Curiosity rover has been exploring since 2012.