A tiny second moon may once have orbited Earth before catastrophically slamming into the other one, a titanic clash that could explain why the two sides of the surviving lunar satellite are so different from each other, a new study suggests. The second moon around Earth would have been about 750 miles (1,200 kilometers) wide and could have formed from the same collision between the … Continue reading Earth Had Two Moons That Crashed to Form One, Study Suggests