If asteroids were apartments, this one would be New York City–style: teensy. On Friday, a 150-foot asteroid, described as roughly the size of an apartment building, flew dangerously near Earth. DA14’s journey was the closest on record to Earth for a space rock its size—missing our planet by only 17,150 miles. While the little guy is too small to see with the naked eye, it would release the equivalent energy of 2.4 million tons of TNT and destroy about 750 square miles if it were to touch ground. NASA estimates an event like this occurs once every 40 years, but the likelihood that an asteroid would strike is once every 1,200 years.