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Another Close Call

October 16, 2011

A cosmic neighbor will pay a close call on Earth tonight. It’ll pass about a quarter-million miles from us — about the same distance as the Moon.

The “neighbor” is an asteroid, designated 2009 TM8. It was discovered two years ago, just hours before its last close call. It’s a chunk of rock and metal that’s probably the size of a house.

If you think you’ve been hearing about a lot of these encounters in the last few years, you’re right. In September of last year, for example, two asteroids passed Earth within a few days of each other. Two others flew by this June — including one that missed us by just 7500 miles.

That doesn’t mean that such encounters are becoming more common, though. Instead, we know about them because astronomers are devoting more effort to finding asteroids whose orbits bring them close to Earth. Larger asteroids are spotted when they’re a good distance away. But small ones are so faint that they’re almost impossible to detect until they’re right on top of us.

Asteroids as small as TM8 are unlikely to create any problems even if they hit us — they usually either burn up or explode high in the atmosphere. The explosions are weak enough that they don’t cause any damage. Any surviving bits are just rubble that either burn up themselves, or that sprinkle Earth with fresh meteorites — the final calling cards of a close cosmic neighbor.

Tomorrow: training for a visit to one of these neighbors — underwater.


Script by Damond Benningfield, Copyright 2011


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