Fewer Asteroids Than Expected Likely to Hit Earth

July 17, 2003

LONDON (Reuters) -- The number of asteroids likely to collide with Earth and cause huge damage is smaller than expected, scientists said this week.

A computer simulation developed by scientists in Britain and Russia shows that asteroids with a diameter of 200 yards will hit the Earth's surface about once every 160,000 years, instead of every 2,500 years.

"Fewer asteroids (than expected) will make it to the surface of the Earth," Phil Bland, of Imperial College in London, said Wednesday.

If a massive near-Earth object measuring more than a kilometer (0.6 mile) in diameter slammed into the planet it would cause global devastation and kill an estimated quarter of the world's population.

But scientists believe an event of that size would only occur about every 700,000 years.

Hollywood films such as "Deep Impact" and "Armageddon" raised public awareness of the threat of near-Earth objects and have prompted calls for early warning systems.

Bland and Natalia Artemieva of the Russian Academy of Sciences used the computer simulation and existing data on impacts to reach their estimates, which are reported in the science journal Nature.

A collision with the Earth 65 million years ago is thought to have wiped out the dinosaurs by changing the global climate. A smaller asteroid is credited with leveling 386 square miles of Siberian forest in 1908.

http://www.cnn.com/2003/TECH/space/07/17/asteroid.prediction.reut/index.html