On February 15, 2013, a small asteroid roughly 55 feet (18 meters) across—about the size of a three-story house—entered Earth’s atmosphere and exploded approximately 13 miles (20 kilometers) above the city of Chelyabinsk, Russia. The asteroid was not detected until it blew up, shattering windows in thousands of buildings and injuring more than 1,000 people. Later calculations showed that this meteor weighed more than 10,000 tons, was traveling at about 40,000 miles per hour, and carried at least 20 times the amount of energy produced by the atomic bomb detonated over Hiroshima, Japan, in 1945.

As damaging as this meteor strike was, things could have been much worse. If this asteroid had struck Earth’s surface and released all of its destructive power at ground level, every structure in an area the size of Chicago would have been flattened, and the loss of human life could have been catastrophic.