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Catch a Falling Asteroid
(From the May/June 2009 issue of StarDate magazine)

Astronomers have caught the first-ever spectrum of an asteroid hurtling to Earth just hours before it exploded in the planet's atmosphere. They used the U.K.'s William Herschel Telescope on La Palma in the Canary Islands.

Data showed that asteroid 2008 TC3 weighed 80 tons, was about 13 feet (4 m) long, had a rare composition, and may have spent several million years in the inner solar system before crashing to Earth.

"This was the first ever predicted impact of an asteroid with the Earth and the very first time an asteroid of any size has been studied before impact," said Alan Fitzsimmons of Queen's University Belfast.

"The faint observed brightness implied a small size, which in turn meant there was little advance warning. It was important to try and figure out what type of asteroid it was before impact, which would give us a better idea of its size and where it came from," he said. "This event shows we can successfully predict the impact of asteroids even with a short warning time, and obtain the astronomical observations necessary to estimate what will happen when the asteroid reaches us."