Was the Red Planet once blue? New evidence points to an ancient ocean on Mars

Graphic illustration showing what it might look like if there were a large ocean on Mars.

Mars may have once possessed an ocean at least as large as Earth's Arctic Ocean, a new study suggests.

Previous research suggested rivers and seas once existed on Mars, raising the question of whether it might have once been capable of supporting life. However, much remains uncertain about how blue the Red Planet once was.