There are roughly 180 known impact craters worldwide and fully a third of them—including some of the biggest—are located in North America. These massive blast zones were formed by meteors, asteroids and comets that slammed into the earth’s surface with a force many times greater than today’s most powerful nuclear bombs. One of those impacts, dating roughly 66 million years ago on Mexico’s Yucatán Peninsula, triggered the mass extinction event that wiped out the dinosaurs.