Scientists have long known that rivers once ran on the surface of the Red Planet, but now they reveal that their existence was relatively recent in Mars' history.

It turns out these ancient rivers flowed freely on Mars for more than a billion years and disappeared just before the planet dried up completely.

New Study Analyzes Martian Riverbeds

In a new paper published in the journal Science Advances, scientists from the University of Chicago completed a catalogue of the rivers that carved such steep riverbeds on Mars' surface.

Lead study author Edwin Kite and the rest of the team pored over data on 200 riverbeds in Mars, which spanned more than a billion years. By analyzing riverbeds, they were able to uncover details about the water and climate of Mars in the past.

Findings reveal that the river runoff in Mars persisted for much longer than previously believed. There were hundreds of these runoffs across the planet, particularly since Martian rivers are known to be much bigger than the ones on Earth.

Climate Of Ancient Mars Still A Mystery

While the team unlocked new knowledge on the existence of rivers on Mars, the revelation made it more difficult for scientists to figure out the climate on the Red Planet billions of years ago.

Ancient Mars only had one-third of the sunlight that Earth currently gets, which is even less sunlight than it gets presently. Thus, the weather should have been colder back then and the surface freezing with not enough heat for liquid water to exist.

Instead, huge rivers gushed heavily on ancient Mars' surface. The river flow was so strong that it flowed continuously, not just during certain parts of the day.

Kite explains in a statement that climate models of ancient Mars need to include a strong greenhouse effect that would maintain an average temperature above the freezing point of water.

Rivers also exhibited strong flow until right before Mars' wet climate ended when it dried up almost instantly.

"Our work answers some existing questions but raises a new one. Which is wrong: the climate models, the atmosphere evolution models, or our basic understanding of inner solar system chronology?" Kite points out.