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Another Encounter

November 7, 2011

A giant radio dish that usually keeps tabs on spacecraft in the far reaches of the solar system is instead keeping tabs on a bit of the solar system that’s come to us: an asteroid that’ll pass just 200,000 miles from Earth tomorrow.

The asteroid is known as 2005 YU55. It’s a chunk of rock about a quarter of a mile in diameter — a relic from the time of the formation of Earth and the other planets.

Two giant antennas are scanning the asteroid with radar. They beam out pulses of radio waves, then listen for some of the energy to bounce back to Earth. One of the antennas is used to track probes in deep space, while the other is the world’s largest radio telescope.

Astronomers will use these observations to create detailed pictures of the asteroid, and to measure its composition. They’ll determine how rough the asteroid’s surface is, and measure how quickly it spins on its axis.

They’ll also plot the asteroid’s orbit more precisely than they could before. YU55’s orbit periodically crosses Earth’s orbit, so there’s a chance that it could hit us sometime in the future. And it’s big enough to do significant damage if it did hit us.

The tracking done to date has ruled out any chance of a collision over the next century, but it’s not precise enough to look any farther than that. The new observations will allow scientists to assess the threat much farther into the future.

Tomorrow: a powerful light show.


Script by Damond Benningfield, Copyright 2011


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