Mars once had a lake 10 times larger than the Great Lakes

Scientists have known for some time that Mars once had lots and lots of water — in fact, some of it is still there — but exactly where it existed on the planet has been pretty difficult to figure out thanks to billions of years of surface erosion. Now, NASA’s Mars Reconnaissance Orbiter has discovered one place on the red planet that held a whole bunch of the life-giving liquid: an incredibly massive lake that, during its peak, held ten times the amount of water of all the Great Lakes, combined.