Did A Comet Kill The Dinosaurs? | Popular Science

Did A Comet Kill The Dinosaurs? | Popular Science:

Some 66 million years ago, a giant space object of some kind slammed into Earth right around the Yucatan peninsula. The resultant explosion sent debris high into the atmosphere; the dust resettled to earth newly enriched with the elements iridium and osmium--elements that are much more abundant in space than on Earth--and formed a thin layer in the rock strata now called the K-Pg boundary. A side effect of this violent impact was the extinction of most of the megafauna--dinosaurs, etc--living during that time. The impact site itself was discovered in 1978 by a geologist working for an oil company, but it wasn't until 1990 that the now-named Chicxulub crater was associated with the proposed impact that caused the mass extinctions. Since 1990, scientists have debated the nature of the rock that hit Earth--asteroid or comet? The scientists know generally how big the explosion would have had to be in order to create the fallout found in drill samples. Based on the size of the explosion and the amount of iridium and osmium deposited at the K-Pg boundary, the most common theory is that the impactor was carbonaceous asteroid about 13 kilometers across. But scientists from Darmouth College argue that the real culprit was a comet.

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