“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,” writes Peter Brannen in Ends of the World about the Chicxulub impact. “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,” hitting Earth with enough force enough to lift a mountain back into space at escape velocity.
This past week we reported that a NASA glaciologist discovered a possible impact crater 22-miles wide buried under more than a mile of ice in northwest Greenland. This follows the finding, announced in November 2018, of a 19-mile-wide crater beneath Hiawatha Glacier – the first meteorite impact crater ever discovered under Earth’s ice sheets. Though the newly found impact sites in northwest Greenland are only 114 miles apart, at present they do not appear to have formed at the same time.
On February 8, we reported that a “very rare species” of asteroid called 2019 AQ3, part of a vast and virtually unknown population zooming through the inner solar system, was detected orbiting close to the Sun every 165 days. Earth is struck by an asteroid 60 meters wide approximately once every 1500 years; an asteroid 400 meters across is likely to strike the planet every 100,000 years.
With these fresh, new discoveries, we thought it would be fascinating and a bit terrifying to present how several of the world’s leading scientists described an epic event that changed the evolutionary history of Earth, and cleared the way for the emergence of the human species and our technological civilization. Sixty Six million years ago a 14 kilometer long, Mount-Everest-sized asteroid blasted a hole in the ground, the Chicxulub Impact, releasing the equivalent of 100 million megatons of TNT creating a 20-mile deep, 110-mile hole and sterilizing the remaining 170 million square miles of the ancient continent of Pangaea, killing virtually every species on Earth.
“It would have felt like the ground beneath your feet had become a ship in the middle of the ocean,” says earth and space science professor Mark Richards at the University of Washington. “Then rocks would have bombarded you from a boiling sky that was beginning to take on a hazy glow. Massive wildfires would have sprouted up as the ground burst into flames. It would have seemed like the end of the world.”
“The pressure of the atmosphere in front of the asteroid started excavating the crater before it even got there,” geophysicist Mario Rebolledo at the Centro de Investigación Científica de Yucatán, told Brannen. “Then, 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.”
In the Yucatán, Rebolledo continues, “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?” Peter Brannen mused.
“Then you’d get the seismic shaking,” observed Melosh. “It would be comparable to a magnitude 12 earthquake. Which . . . well, there’s no such thing as a magnitude 12 seismic earthquake because the elastic strain [of the earth’s crust] can’t contain that much energy, but it is certainly possible for a big impact.”
“The universe is a violent place,” observed the late physicist Stephen Hawking: “Stars engulf planets, supernovae fire lethal rays across space, black holes bump into each other and asteroids hurtle around at hundreds of miles a second. An asteroid collision would be something against which we have no defense. The last big such collision with us was about 66 million years ago and that is though to have wiped out the dinosaurs, and it will happen again.”
The Daily Galaxy, Max Goldberg and PeterBrannen.com
Image credit top of page: With thanks to The Day the Dinosaurs Died is on BBC2