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Did Asteroid-Belt Collision Doom the Dinosaurs?
The latest dinosaur-extinction scenario, courtesy of Nature:
Chunks of space rock are zipping along the asteroid belt between Jupiter and Mars when suddenly there’s a collision that sends debris careening through the Solar System. This happens about 160 million years ago.
Fast forward through the next 95 million years:
Shards of the asteroid debris are moved by Jupiter’s gravity and the sun’s heat. At at least one good-sized chunk heads into the path of that pretty little blue-green planet orbiting third from the sun.
Other research suggests what happens next.
The impact of that fateful asteroid chunk sets off a cataclysm on Earth.
What’s now known as the Chicxulub impactor slams through the Earth’s atmosphere until it strikes a shallow shelf along the Yucatan Peninsula. The impact creates a 100 mile-wide crater, sets off magnitude-10 earthquakes, unleashes tsunamis never seen before or since.
Forests that are not flattened burn up in raging fires that burn as far away as Africa. Rock and debris from the asteroid impact travel thousands of miles — some seen in Colorado. A plume of vaporized asteroid envelopes the Earth.
The skies go dark.
They stay dark as deep night for months.
Toxic, sulfurous acid rain falls.
The Earth’s surface grows cold. Its creatures die in numbers unfathomable.
Ninety percent of marine organisms disappear. The collapse of plankton leads to collapse of the marine food chain. Seventy-five percent of all living species become extinct, including the dinosaurs. Smaller creatures, especially nocturnal ones, have the best chance for survival.
The geologists who first described this crater named it Chicxulub from a Mayan word meaning roughly “tail of the devil.” Very appropriate.
All of this begs the question: How can we be certain another asteroid won’t wipe out most life on Earth again? The scientists’ answer in Nature’s Sept. 6 edition: We can’t.
Over the past 100 million years, the rate of impact craters appearing on Earth and the moon appears to have at least doubled, and possibly quadrupled, evidence of this great asteroid crash in the Baptistina family of asteroids, long ago and far away.
Science magazine’s Richard A. Kerr writes that the study by William F. Bottke, David Vokrouhlicky and David Nesvorny of the Southwest Research Institute in Boulder, Colorado is already shifting the attention of scientists who try to assess the risk posed by impact hazards. He says they are shifting attention away from super-fast comets to debris-spewing asteroid-belt collisions, like the one that may have spawned Chicxulub.
“The threat from the Baptistina family may have waned,” Kerr writes, “but more catastrophic disruptions are inevitable.”
Do you buy the asteroid-extinction theory?
Comments
By mike murhead
September 27, 2007 8:16 AM | Link to this
this sucks