StarDate: August 31, 2010

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A month from now, a space rock that could be as big as a basketball arena will sweep about a million and a half miles from Earth. There's no danger of it hitting us, but it's worth keeping an eye on because it periodically passes even closer to us. It's probably big enough to do some pretty good damage if it hit.

The small asteroid was discovered with a telescope in Australia that scans the sky for objects that could one day threaten our planet. Several other telescopes in the United States and elsewhere do the same thing.

And they're doing the job pretty well. Astronomers have cataloged about 7,000 N-E-Os -- Near Earth Objects -- mostly asteroids with orbits that come close to Earth's. About one in six is classified as "potentially hazardous" -- their orbits come really close to Earth's.

Most NEOs are small, like the one that'll pass us at the end of September. But a few are big enough to cause damage on a global scale. And that's why it's so important to find and track them. With enough observations, astronomers can plot an asteroid's orbit decades into the future, telling us if it's on a collision course. Enough warning should give us time to nudge the asteroid off course just enough to miss us.

The job isn't done yet, though -- hundreds or even thousands more NEOs await discovery. So telescopes around the world will continue to watch the skies for dangerous invaders.

We'll have more about asteroids tomorrow.

Script by Damond Benningfield, Copyright 2010

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