How did Mars go from wet to dry?
NASA's MAVEN probe says: blame the sun and a wimpy magnetic field. (Video via NASA)
When solar flares erupt, high-energy particles batter the planets. (Video via NASA)
Earth's powerful magnetic field shields the atmosphere. But with its weak field, Mars takes the full brunt. (Video via NASA)
So the atmosphere blew away and so did most of the water. (Video via NASA)
This video includes images from NASA.