Harvard scientists have a new take on what wiped out the dinosaurs

The kind of comet that killed T. rex and friends from our planet might be more common than previously thought.

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Eric Mack
2 min read

Artist's illustration of a comet bound for Earth.

Harvard-Smithsonian Center for Astrophysics

Harvard's most controversial astronomer has a new theory about the space rock that took out the dinosaurs. There's reason to believe it came from farther afield than previously assumed, he says. 

Avi Loeb has been making waves for a few years now by arguing that first ever interstellar object Oumuamua could be a wayward piece of alien technology from far beyond our solar system. But his latest paper has nothing to do with that.

Loeb and Harvard University astrophysics undergraduate student Amir Siraj suggest in a new study published Monday in Scientific Reports that the Chicxulub Impactor, which ended the rule of the thunder lizards, originated from the edge of our own solar system.

A popular theory about the demise of the dinos says the impactor likely originated from the asteroid belt between Mars and Jupiter, but Loeb and Siraj use statistical analysis and gravitational simulations to calculate that more Earth impactors actually originated from the far-off Oort cloud where most long-period comets hail from.

The pair's calculations suggest some such comets can get knocked off track on their journey toward the inner solar system, with potentially catastrophic consequences.

"The solar system acts as a kind of pinball machine," Siraj explained in a statement. "Jupiter, the most massive planet, kicks incoming long-period comets into orbits that bring them very close to the sun."

So-called sungrazer comets can then be torn apart by the pull of the sun's gravity.

"And crucially, on the journey back to the Oort cloud, there's an enhanced probability that one of these fragments hit the Earth," Siraj said. 

Watch this: Q&A with Harvard's Avi Loeb on our alleged extraterrestrial visitor

The research finds that the odds of such an impact are significantly higher than previously thought and that the new rate of impact lines up with the age of the Chicxulub impact crater in the Gulf of Mexico. A comet fragment from the Oort cloud also matches up with the unusual makeup of the impactor better than an asteroid from closer to home.

Even more important than solving the mystery of what killed off the dinosaurs, Loeb says a deeper understanding of natural traffic from deep space could also be important if a potential impactor should threaten our planet in the future.

"It must have been an amazing sight," he said, "but we don't want to see that again."  

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