Millions of years ago when the some 75% of all the species on the planet Earth were wiped out due to an impact. Initial thoughts were that these space rocks might have gone rogue out of the asteroid belt within the regions of the planet Jupiter.

However, newer studies suggests otherwise as they might not the asteroid from between our neighbor Mars and Jupiter. The study show that the impacts was likely pieces of comet from the Oort cloud — a mass of icy bodies that surrounds the outer edges of our solar system.

So-called long-period comets from the Oort cloud take hundreds of years to take a lap around the sun, and previous studies had suggested that their chances of crossing the path of a planet are too low to make them a likely culprit for the extinction of the nonavian dinosaurs (and 75% of all other life on Earth roughly 66 million years ago). But the new research, published Feb. 15 in the journal Scientific Reports, finds that Jupiter’s gravity pushes about 20% of these long-period comets close to the sun, where they break apart. The resulting fragments are 10 times more likely than other Oort cloud comets to hit Earth. 

A massive impact that nearly killed life

The impact of the comet left its mark on the planet which can be seen in the town of Chicxulub, Mexico. The impact marked the end of the Cretaceous period and the mark measures 93 miles (150 kilometers) in diameter.

The rock was at least 6 miles (9.6 km) wide and hit the planet at about 44,640 mph (71,840 km/h), according to researchers at the University of Texas at Austin. It triggered a mile-high tsunami and melted the crust at the point of impact.

What isn’t known is where the comet might have popped out from. Studies which includes the geological analysis of the crater further suggests that it was a carbonaceous chondrite which is a type of meteor that makes up only about 10% of those found un the main asteroid belt within the solar system – near Jupiter.

So there are evidences pointing to this comet being a rogue one that possibly couldn’t be held back due to the powerful gravitational pull of the gas giant Jupiter but it’s also possible that this object came as far as the Oort Cloud because of the compositions of the comet which is said to be more common in the edge of the solar system.

Author Avi Loeb, an astronomer at Harvard University and Amir Siraj who is also an undergraduate of astronomy thinks this might be the possible location of the dinosaur-killing impact that wiped out more than half of all life forms on Earth.

The researchers were also able to simulate the paths of long-period comets from the Oort cloud past Jupiter and then found that the gravitational field of the solar system’s largest planet turns about one-fifth of long-period comets into “sun-grazers,” which are comets that pass very close to the sun. At close range, the sun’s gravity pulls harder on the close side than on the far side of this type of comet, creating tidal forces that can break the comet apart.

Any chance of future collision?

The fragments from these celestial breakups are more likely than an intact comet to intersect with Earth on their return journey toward the Oort cloud; such events are capable of producing a Chicxulub-size impact every 250 million to 730 million years, the researchers said.

“Our paper provides a basis for explaining the occurrence of this event,” Loeb said in a statement. “We are suggesting that, in fact, if you break up an object as it comes close to the sun, it could give rise to the appropriate event rate and also the kind of impact that killed the dinosaurs.”

There is also the Zhamanshin crater in Kazakhstan which is the largest impact crater made in the past million years and scientists think it might have also been created by carbonaceous chondrite according to Loeb and Sajir in their new paper which is meant to prove this theory.

More research on Earth’s impact craters and comet composition could help bolster the evidence for the hypothesis.

“We should see smaller fragments coming to Earth more frequently from the Oort cloud,” Loeb said. “I hope that we can test the theory by having more data on long-period comets, get better statistics and perhaps see evidence for some fragments.”

Originally published on Live Science