Minggu, 21 Agustus 2022

Not One Asteroid, But TWO, May Have Killed Off the Dinosaurs, Scientists Say

Scientists have long believed the Chicxulub asteroid smacked Earth near the Gulf of Mexico, causing about a 100-million-megaton blast devastating enough to erase the dinosaurs from Earth. That burst created a short-lived thermal pulse in excess of 10,000 degrees, which is certainly lethal enough to have destroyed nearby life. But the massive asteroid may have had some help from a second "sibling" asteroid, scientists say.

More than five miles in diameter beneath the North Atlantic Ocean, the newly-discovered Nadir Crater lies about 250 miles off the coast of West Africa—and researchers believe that the asteroid that may have caused it about 66 million years ago could have been that dino-killing helper. There are two prevailing theories about this second asteroid, according to a new study, published August 17 in Science Advances: that the asteroid may have been a broken-off piece of the Chicxulub asteroid, or that it was a wholly separate asteroid from an impact cluster.

Led by Veronica Bray, a research scientist at the University of Arizona Lunar and Planetary Laboratory, the new work includes simulations that show the collision that formed the Nadir Crater was powerful enough to cause at least widespread local disruption.

"This would have generated a tsunami over 3,000 feet high, as well as an earthquake of more than magnitude 6.5," she says in a university press release. "Although it is a lot smaller than the global cataclysm of the Chicxulub impact, Nadir will have contributed significantly to the local devastation. And if we have found one 'sibling' to Chicxulub, it opens the question: Are there others?"

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