Asteroid on Collision Course with Earth

Science's Doomsday Team vs. the Asteroids

By Guy Gugliotta
Washington Post Staff Writer
Saturday, April 9, 2005; Page A01


Astronomer David Tholen spotted it last year in the early evening of June 19, using the University of Arizona's Bok telescope. It was a new "near-Earth object," a fugitive asteroid wandering through space to pass close to Earth.

Tholen's team took three pictures that night and three the next night, but storm clouds and the moon blocked further observations. They reported their fixes to the Minor Planet Center in Cambridge, Mass., and moved on.

Six months later, Tholen's object was spotted again in Australia as asteroid "2004 MN4." In the space of five days straddling Christmas, startled astronomers refined their calculations as the probability of the 1,000-foot-wide stone missile hitting Earth rose from one chance in 170 to one in 38.

They had never measured anything as potentially dangerous to Earth. Impact would come on Friday the 13th in April 2029.

The holidays and the tsunami in South Asia pushed 2004 MN4 out of the news, and in the meantime additional observations showed that the asteroid would miss, but only by 15,000 to 25,000 miles -- about one-tenth the distance to the moon. Asteroid 2004 MN4 was no false alarm. Instead, it has provided the world with the best evidence yet that a catastrophic encounter with a rogue visitor from space is not only possible but probably inevitable.

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