Mercury's not such a dull planet after all. A new batch of papers in Science spells out evidence of a busy volcanic past and describes an unusual impact crater that would stretch from Boston to DC, reports Wired. The papers, which draw from the October flyby of NASA's Messenger craft, speculate that 40% of the planet's surface was formed by volcanoes. That's a huge shift—prior to Messenger's trip, scientists weren't sure if Mercury had any volcanic activity at all.
“It’s definitely not this picture of an ancient world where everything that happened to it happened billions of years ago and nothing happened since then,” said a scientist at the Smithsonian Institution. “We’re seeing a very dynamic planet that has a lot going on today.” (Read more Mercury stories.)