LOS ANGELES (AP) _ An asteroid large enough to wipe out France hurtled past the Earth at a distance of a half-million miles just days after scientists spotted it.
The asteroid, dubbed 2001 YB5, came within 520,000 miles of Earth on Monday, approximately twice the distance of the moon.
Dozens of asteroids pass close by the Earth each year, though 2001 YB5 was closer than most. On Friday, for instance, an asteroid known as 2001 UU92 will pass with 11 million miles of Earth.
Asteroid 2001 YB5, estimated to be 1,000 feet across, was traveling about 68,000 mph relative to the Earth when it zipped past.
``It's a fairly substantial rock. If it had hit us at that sort of speed, you would be taking out a medium-size country, France, I suppose, or Texas, or something of that order,'' said Jay Tate, director of the Spaceguard Centre in Wales.
Astronomers with the NASA's Near-Earth Asteroid Tracking program discovered 2001 YB5 on Dec. 26. Soon after, astronomers calculated the asteroid's orbit and determined there was no danger it would strike Earth.
Had it been on a collision course, it would have created ``one of the worst disasters in human history,'' said Steven Pravdo, the NEAT project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
``What could we have done about it? The answer is not much,'' Pravdo said.
As astronomers become aware of more asteroids passing close to the Earth, they seek a standardized way of alerting the public to the hazard they might pose. Among programs already in place is the Spaceguard Centre's Comet and Asteroid Information Network, which began work Jan. 1.