To make a red planet purple, you'd have to add blue, which is what Mars would have looked like when a third of its surface was covered with one huge ocean:
Researchers have long thought they saw the remnant of an ancient seabed on its surface, but they had a hard time explaining what happened to the oceanfront property. There were features that looked like remnants of shorelines, but they varied so much in elevation that it was hard to explain how they could have bordered the same sea.Link.
Now a team of U.S. and Canadian researchers have explained these variations and drawn the outlines of the ocean that existed more than 2 billion years ago. They report in Nature that these features look like shorelines that were warped when the planet’s spin axis shifted.
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“What we don’t know is what caused the poles to shift on Mars and what happened to the water,” says the lead author, Taylor Perron of Harvard, who worked with colleagues from the University of California, Berkeley, the Carnegie Institution and the University of Toronto. “The ocean may have been gradually converted into water vapor, moved to higher elevations, and flowed beneath the surface. There could be a large mass of water deep within Mars.”
Indexed by tags science, astronomy, geology, Mars, ocean.