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Collision in space may have doomed dinosaurs

September 08, 2007|John Johnson Jr. | Times Staff Writer

A game of asteroid billiards may have set in motion the chain of events that wiped out the dinosaurs 65 million years ago, a team of researchers announced this week.

According to the Czech-American team, the giant rock that hit Earth was probably a fragment from a collision in the asteroid belt about 100 million years earlier.

The researchers -- William Bottke and David Nesvorny of the Southwest Research Institute in Colorado and David Vokrouhlicky of Charles University in Prague -- used computer models to determine that the process started with a collision between the 102-mile-wide Baptistina asteroid and a smaller companion.

The collision created the Baptistina asteroid family, thousands of smaller rocks more than a mile across, according to the research published Thursday in the journal Nature.

As the fragments spread out, some drifted onto a superhighway in space that allowed them to escape the asteroid belt between Mars and Jupiter.

About 2% of the escapees went on to hit Earth, while some of the others pummeled the moon, the researchers said.

One fragment created the 108-mile-wide Chicxulub crater on Mexico's Yucatan peninsula. Scientists think the impact filled the atmosphere with soot and smoke for years, causing a widespread die-out of life, including the dinosaurs that had successfully ruled Earth for millions of years.

Another fragment is thought to have created the 50-mile-wide Tycho crater on the moon.

"We are in the tail end of this shower now," Bottke said. "Our simulations suggest that about 20% of the present-day, near-Earth asteroid population can be traced back to the Baptistina family."

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