Biggest Crater in the Solar System Found on Mars

For a small planet, Mars sure knows how to go big. It's about half as large as Earth, but it's got the hugest volcano in the solar system in the Arizona-sized Olympus Mons and the grandest of all canyons in the 7 kilometer-deep Vallis Marineris. Now it can add its coolest, most-braggable title: the Biggest Impact…