Earth dodged an asteroid by just 6 hours, crossing paths with a potential city-killer

Earth narrowly missed an asteroid, 4581 Asclepius, on March 22, 1989, by just six hours. This 1,000-foot space rock, detected nine days later, would have caused city-leveling devastation. The scare pushed for asteroid watch programs. "An impact would have released a devastating amount of energy," said Harvard professor Avi Loeb.