Wednesday, December 30, 2009

Questioning the Dinosaur-Killing Asteroid Theory

New research challenges the thought that the asteroid impact that killed the Dinosaurs also sparked a global firestorm.

Scientists modeled the consequence that sand-sized droplets of liquefied rock from the impact had on atmospheric temperature. The asteroid is thought to have gouged away the Chicxulub crater on the Yucat√°n Peninsula in Mexico.

Formerly it was thought that the falling spherules, as the tiny rocks are called, heated up the atmosphere by several degrees for up to 20 minutes — hot enough and long enough to cause whole forests to spontaneously burst into flames.

As evidence for this, scientists pointed to what appears to be carbon-rich soot from burned trees exposed in the thin band of debris dating back to the impact some 65 million years ago, a shift in geologic time called the K-T boundary.

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