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A Harvard University study indicates that the space rock that wiped out the dinosaurs was fragments from a comet that flew near the sun

A Harvard University study indicates that the space rock that wiped out the dinosaurs was fragments from a comet that flew near the sun

An artist’s depiction of the moment the Chicxulub asteroid hit present-day Mexico 66 million years ago. Chase Stone

About 66 million years ago, a space rock more than 6 miles wide collided with the Earth, and it struck the Earth that is now part of Mexico.

The impact sparked hundreds of miles of forest fires, triggered a tsunami as high as a mile, and released billions of tons of sulfur into the atmosphere. This gaseous fog blocked the sun, cooling the Earth and wiping out the dinosaurs, along with 75% of all life on the planet.

But the origins of those dinosaur killer rocks, called Chicxulub, have remained mysterious.

Most theories state that Chicxulub was a massive asteroid. Hundreds of thousands of these rocks lie in a donut-shaped ring between Mars and Jupiter. But in a study Two Harvard University astrophysicists, published Monday, proposed an alternative idea: that Chicxulub was not an asteroid at all, but rather a piece of fragment from an icy comet that had been pushed near the sun by Jupiter’s gravity.

Asteroids and comets are classified as space rocks By NASABut they differ in key respects: Comets are made of ice and dust outside our solar system and are generally small and fast-moving, while rocky asteroids are larger, slower, and form closer to the sun.

“We suggest that, in fact, if you disassemble an object as it approaches the sun, it could lead to the appropriate event rate and also the type of effect that killed the dinosaurs,” said Avi Loeb, an astrophysicist and Harvard cosmologist and co-author of the new study. In a press release.

The solar system functions like a “pinball machine” for comets

Meteorite Armageddon shutter

An artist’s depiction of an asteroid approaching Earth. Vadim Sadovsky / Shutterstock

Most asteroids come from asteroid belt Between the inner and outer planets of the solar system. But NASA Scientists Those who keep an eye on space objects passing near Earth have yet to discover where Chicxulub came from.

In the new study, published in Scientific Reports, Loeb and his co-author, Amir Serraj, indicate that Chicxulub did not come from the asteroid belt. Instead, they say it likely originated outside of our solar system, in an area called Oort cloud.

Think of the Oort cloud as a ring made up of a trillion pieces of ice debris that lies outside and surrounds the farthest reaches of the solar system. It is located at least 2,000 times farther from the sun than the Earth. Comets originating in the Oort Cloud are known as Long-range comets Because it takes a long time to complete one revolution around the sun.

But these comets can sometimes be deflected by the gravitational pull of massive planets like Jupiter. Such a modification in the orbit of a comet could send it off a path much closer to the sun.

“The solar system works like a kind of pinball machine,” said Saraj. In the version.

Comets approaching the sun are called “Sangers”. The new study calculated that about 20% of the Oort comets are rocky comets. As they approach our star, its attraction begins to deconstruct them. Parts of the comet infiltrate and may head towards nearby planets.

The study’s authors say this is a “satisfactory explanation for the origin of the probe” that killed the dinosaurs.

The asteroid versus comet argument has not been settled

Chicxulub_impact asteroid

A painting depicting an asteroid crashing into the shallow tropical seas of the Yucatan Peninsula in what is today southeastern Mexico. It is believed that what happened in the aftermath may have caused the extinction of the dinosaurs. Donald Davis / NASA

Siraj and Loeb aren’t the only scientists who believe that a comet, rather than an asteroid, wiped out the dinosaurs. A group of researchers from Dartmouth College did the same Proposed in 2013 That a high-speed comet could have created the Chicxulub crater.

The Chicxulub hit the ground at 12 miles per second (43,200 miles per hour), which is about 30 times the speed of a hypersonic jet. The resulting 100-mile-wide crater extended to 12 miles deep into the Gulf of Mexico. Some scholars Estimated The force of the asteroid was equivalent to 10 billion atomic bombs used in World War II.

But not all researchers are convinced that the comet caused this damage.

Natalia Artemieva, a senior scientist at the Institute of Planetary Sciences in Arizona, He told the New York Times The comet fragments from Sungraser were too small to form the Chicxulub crater. Bill Potky, a planetary scientist at the Southwest Research Institute in Colorado, suggested that the study overestimates the frequency of small comets – and thus the amount of fragments that comets produce.

Existing evidence favors the idea that Chicxulub was an asteroid, but it is not conclusive, Bottke He told the Times. “There is still room for maneuver if someone really wants to be guilty. I just think making this case is really difficult.”

However, Siraj and Loeb said their theory is backed by the type of material found deep in the Chicxulub crater and other craters in South Africa and Kazakhstan. This substance, carbon chondrite, may have come from comets. The study authors write that while only 10% of asteroids in the asteroid belt are composed of carbon chondrites, the material is likely “widespread in comets.”

The only samples collected from a comet were brought back into space in 2006. They revealed that the object, called Wild 2, was made of carbon chondrite.

Cooper's rings in the cloud

Artwork depicting icy cores of small comets outside of Neptune at the edge of our solar system. ESO / CE. Grain knives

Finding the correct answer in the Chicxulub debate is beneficial because it may help researchers understand the likelihood of a similar effect in the future. Only two or three comets have hit Earth’s Oort cloud in the past 500 million years. According to one study. By contrast, according to the Planetary Society, a Chicxulub-sized asteroid impacts Earth every time 100 million years or so.

Siraj and Loeb modeled the number of long-range comets close enough to the sun to throw large fragments toward Earth. Their numbers indicate that Chicxulub-sized objects have struck Earth ten times over the course of its history than scientists previously thought.

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