An asteroid half a mile wide, blazing through space at nearly 50,000 m.p.h., skirted past Earth last month in a cosmic "close call" unrivaled in the last 50 years, NASA officials said Wednesday.
The asteroid, identified as 1989FC, passed within 500,000 miles of Earth--about twice the distance to the moon--on March 23, the National Aeronautics and Space Administration reported.
"On the cosmic scale of things, that was a close call," said Dr. Henry Holt, an amateur astronomer from Flagstaff, Ariz., who discovered the asteroid while working on a NASA project.
Bevan French, a scientist with NASA's solar system exploration division, said if the asteroid had collided with Earth the impact would have been equivalent to the explosion of 20,000 hydrogen bombs and would have created a crater at least 5 miles across--or "enough to destroy a good-sized city."
If it had hit an ocean, it would have caused tidal waves that would have swept over coastal regions, French said.