Around 470 Million years ago, two asteroids collided in the asteroid belt between the planets Mars and Jupiter.  This sent fragments everywhere, and millions of years later these fragments moved into the inner solar system, many of which struck the Earth as meteorites.  Recently, in Jämtland county, Sweden, a team of geophysicists has identified a pair of impact craters that were formed at the same time, likely from two separate impactors.  One of the craters is a massive 7.5 Km across, while the other is smaller at 700 meters.  This is the first time a double impactor has been scientifically confirmed on Earth....