Mars Used to Have a Huge Ocean, but Then a Mega-Tsunami Ruined Everything

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The history of Mars is up to almost as much scrutiny as the history of Earth. The fourth planet from the Sun is a cold and lifeless world these days, but scientists believe the planet once had a large ocean. A new study looking at the Martian transition from water-filled to barren argues that just like ancient Earth, ancient Mars was struck by an extremely powerful mega-tsunami that was trigged by a large asteroid.

The theory calls to mind images of Earth's own transformation approximately 65 million years ago, when an asteroid named Chicxulub triggered a mass extinction event and altered the planet's history. There's no firm understanding of how the mega tsunami would have affected Mars, but the planet would have seen waves up to 1,000 feet tall crashing down.

Francois Costard, an astronomer at the French National Centre for Scientific Research, is the lead author of the new study promoting the theory, which was published in JGR Planets. The paper suggests the tsunami took place on the Martian northern hemisphere approximately 3.5 billion years ago.