ESA officials made the announcement on Thursday that they have discovered an ancient riverbed carved into the Red Planet's surface.

A team of scientists from the European Space Agency have reportedly discovered an ancient riverbed on Mars, which is just the latest piece of evidence to support the theory that water once flowed across the Martian surface. The photos were taken last year, and were released late on Thursday by the ESA. ESA officials made the announcement on Thursday that they have discovered an ancient riverbed carved into the Red Planet's surface. The images were taken by the ESA's Mars Express, and have left astronomers around the world stunned as this may be the most definitive evidence to date that supports the theory that water once flowed on Mars. The area, which is known as Reull Vallis, contains a river-like channel that likely formed billions of years ago. The channel, which is 1,500-km in length, is lined with tributaries that look to resemble tributaries found on Earth. Interestingly, the river is as wide as 4 miles at some points. Astronomers say that at some points the river is nearly 1,000 feet deep, and may be one of the most geologically important features on Mars. Scientists speculate that due to the depth of the channel, the riverbed was once occupied by water and large chunks of ice. According to geologists, water likely flowed through Reull Vallis between 3.5 to 1.8 billion years ago during a time known as the Hesperian period. Further research is needed to confirm the age of the channel.