Meet the asteroids

Are they gonna hurt us?

Will they obliterate the earth?

How are asteroids found?

Did asteroids deliver life?

What are they made of?

What about comets?

Asteroids in orbit

A striking possibility
Despite the recent false alarm, and despite the two movies on the subject, the odds of getting whacked by an asteroid or comet are pretty remote. Space may be small to Hollywood's mind, but it's really a big place, and there's plenty of space for us -- and for speeding hunks of rock. "None of the known near-Earth objects will be threatening in the next century," assures Donald Yeomans, head of the near-Earth objects program office at the Jet Propulsion Laboratory (JPL).

wolf creek australia
This terrestial impact crater known as Wolf Creek was created 300,000 years ago. This relatively well-preserved crater is partly buried under windblown sand in the flat desert plains of north-central Australia. Courtesy of V L Sharpton/NASA.

The odds of anything else striking hard enough to cause havoc are "exceedingly small," he adds. (Just to be on the safe side, here's a list of projected close encounters in the next 33 years.)

Problem is, most asteroids are unknown, which makes this assurance somewhat less than ironclad. According to one estimate, 1,500 to 2,000 asteroids larger than 1 kilometer in diameter are orbiting near Earth; most are unknown.

That unsettling information chasm has spawned a miniature asteroid-search industry determined to find Near Earth Objects (NEOs) before a monster finds us.

NASA has just doubled its asteroid search budget -- to a princely $3 million. Yet this small change is buying major results.

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The Why Files
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