"Giant Fireball" Impact in Peru Upends Meteorite Theory

Richard A. Lovett
for National Geographic News
March 11, 2008

A meteorite that smacked into the Peruvian highlands last September may have punched holes into long-held theories about how such meteorites, called chondrites, interact with Earth's atmosphere.

Chondrites are stony chunks of asteroid, likely common in space, that contain materials similar to those found in Earth's crust.

Scientists have thought that the objects break up into flattened clusters of particles that spread out like a pancake as they plunge into Earth's atmosphere, said Peter Schultz, a geology professor from Brown University who studies meteorite impacts.

This would cause the pieces to burn up in the atmosphere or slow down and drop to the ground like rocks dropped from an airplane.

The fragments would make holes in the ground like pits—but not craters, according to Schultz.

Yet "the [Peruvian] meteorite kept on going at a speed about 40 to 50 times faster than it should have been going," defying the theory, Schultz said.

In fact it came down intact as a giant fireball at about 15,000 miles (about 24,000 kilometers) an hour, creating a 50-foot-deep (15-meter-deep) crater.

This unusual occurrence had some scientists wondering if the Peruvian crater might have been caused by something different, or even faked, Schultz said. "At the time, rumors were flying."

So he traveled to Peru to look at the crater, which is located in the village of Carangas, near the Bolivian border.

The Real Thing

The most likely alternative was that the impact was simply the largest of a widely strewn field of meteor fragments, and the scientists found only only one crater.

The fabricated-meteorite-crater theory was then ruled out when Schultz's team found "shock" features and intricate mixing of the meteoritic dust in the surrounding rock, indicating that something had indeed crashed into it.

Continued on Next Page >>




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