Asteroid swings safely past Earth

LOS ANGELES -- Whew, that was close. An asteroid the size of a tour bus streaked harmlessly past Earth on Monday, passing within 7,600 miles.

Discovered only last week, the relatively small space rock made a hairpin turn around the planet at about 8 a.m. Central Standard Time, sailing high over the southern Atlantic Ocean.

In truth, there was never any doubt it would miss. But given the vastness of the universe, 7,600 miles is practically a stone's throw away, at about three times the distance between New York and Los Angeles.

Asteroids of this size typically brush by Earth every six years. In fact, earlier this year, a smaller one came even closer to the planet, passing within 3,500 miles.

Even if the latest one had aimed straight for Earth, it would have burned up in the atmosphere and not caused any damage on the ground.

"We're just waking up to the fact that Mother Nature has been shooting these things across the bow for millennia," said Don Yeomans, who heads the program that tracks potentially dangerous space rocks at NASA's Jet Propulsion Laboratory in Pasadena.

It was expected to be bright enough that someone might be able to see it with a medium-sized telescope.

Asteroids are leftovers from the formation of the solar system some 4.5 billion years ago. Pieces of asteroids -- meteorites -- constantly break away and make fiery plunges through the atmosphere.

Objects bigger than two-thirds of a mile are major killers and hit Earth every several hundred thousand years. Scientists believe it was a six-mile-wide asteroid that wiped out the dinosaurs 65 million years ago.

Scientists frequently monitor these potential threats to get better data on their paths and likelihood of hitting Earth. Over the years, NASA has identified and tracked 8,110 near-Earth objects -- comets or asteroids -- that are bigger than several feet across. Of those, 1,237 are considered "potentially hazardous asteroids."

Though scientists, engineers and former astronauts have pondered ways to protect Earth from a catastrophic collision with an asteroid, there is no firm plan like something out of the Hollywood movie "Deep Impact."