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The dinosaur-killing asteroid that struck Earth was unbelievably huge and fast

posted by Jason Kottke   Jun 26, 2018

Humans are so small compared to the size of the Earth, it’s sometimes difficult to comprehend the scale of things like, say, the massive meteorite that struck the Yucatan peninsula about 66 million years ago, an event that triggered the mass extinction of plants and animals, including the dinosaurs. In his recent book, The Ends of the World, Peter Brannen takes a crack at explaining just how big the meteorite was and how quickly the event occurred.

“The meteorite itself was so massive that it didn’t notice any atmosphere whatsoever,” said Rebolledo. “It was traveling 20 to 40 kilometers per second, 10 kilometers — probably 14 kilometers — wide, pushing the atmosphere and building such incredible pressure that the ocean in front of it just went away.”

These numbers are precise without usefully conveying the scale of the calamity. What they mean is that a rock larger than Mount Everest hit planet Earth traveling twenty times faster than a bullet. This is so fast that it would have traversed the distance from the cruising altitude of a 747 to the ground in 0.3 seconds. The asteroid itself was so large that, even at the moment of impact, the top of it might have still towered more than a mile above the cruising altitude of a 747. In its nearly instantaneous descent, it compressed the air below it so violently that it briefly became several times hotter than the surface of the sun.

“The pressure of the atmosphere in front of the asteroid started excavating the crater before it even got there,” Rebolledo said. “Them when the meteorite touched ground zero, it was totally intact. It was so massive that the atmosphere didn’t even make a scratch on it.”

Unlike the typical Hollywood CGI depictions of asteroid impacts, where an extraterrestrial charcoal briquette gently smolders across the sky, in the Yucatan it would have been a pleasant day one second and the world was already over by the next. As the asteroid collided with the earth, in the sky above it where there should have been air, the rock had punched a hole of outer space vacuum in the atmosphere. As the heavens rushed in to close this hole, enormous volumes of earth were expelled into orbit and beyond — all within a second or two of impact.

“So there’s probably little bits of dinosaur bone up on the moon,” I asked.

“Yeah, probably.”

I don’t know if your eyes are as wide as mine are about now but…