Early Mars once had an atmosphere and even oceans, but as the active sun evolved, it began to strip the Red Planet of its air, a process that has also been spotted in action outside the solar system. NASA's MAVEN mission, currently orbiting Mars, has taken measurements that have allowed scientists to determine that, if the sun were as quiet through its history as it is now, the Red Planet would have lost about 63,000 gigagtons of atmosphere, a number that corresponds to a surface layer of water 15 feet (4.5 meters) deep. An artist's rendering of a solar storm stripping charged particles from the Red Planet's upper atmosphere. Photo Credit: NASA/GSFC #maven #journeytomars #nasa #redplanet #exploredeepspace