Huge Space Rocks Are Hitting Earth Twice as Often as Before


Huge rocks from outer space, or asteroids, fall from the sky more than they have in the past. But there is no need to worry.

A new study has shown that during the last 290 million years, large asteroids have crashed into Earth more than twice as often as in the 700 million years before. The journal Science published the study in January.

But, even with the highest accident rate, asteroids only hit the Earth every million or few million years.

The space agency of the United States, NASA, lists its observation of large space rocks that could hit the Earth. It does not show any major threat in the near future.

The biggest known risk is an asteroid 1.3 kilometers wide with a probability of 99.988 percent that it will miss the Earth when it passes in 861 years.

The scientist at the University of Toronto, Sara Mazrouei, led the study. She told the Associated Press that she is not worried about asteroids hitting the Earth because they are very rare events.

“It’s just a game of odds,” he said.

Mazrouei worked with researchers in Great Britain and the USA. UU In the study. Together they put together a list of the big brands that asteroids leave on planets and other objects, also known as impact craters.

The researchers observed impact craters on Earth and its moon that were more than 20 kilometers wide. A space rock 800 meters wide is needed to create such a large hole.

They also estimated the dates of the craters. The team had 29 craters that were less than 290 million years old. And they found nine of between 291 million years and 650 million years.
This mosaic image made from 12 PolyCam images collected on December 2, 2018 and provided by NASA shows the asteroid Bennu.
This mosaic image made from 12 PolyCam images collected on December 2, 2018 and provided by NASA shows the asteroid Bennu.

Rebecca Ghent, another scientist at the University of Toronto, also worked on the study. He noted that we can see relatively few large craters on the surface of the Earth because the planet is more than 70 percent of the oceans. In addition, the movement of large ice mountains, also known as glaciers, covered some of them.

The team estimated there were 260 space accidents on Earth in the last 290 million years. And that collision rate is 2.6 times more than the 700 million years prior to that date.

As the glaciers mostly covered older craters, scientists studied the craters on the moon to estimate the age of those between 650 million and one billion years on Earth. The moon is close enough to Earth to be on the same path as the asteroids and its craters last longer.

So, what happened almost 300 million years ago?

“Maybe an asteroid family broke in the asteroid belt,” Mazrouei suggested. The space rocks then went towards Earth and the moon, Ghent added. The planet then received a few more hits because it is a bigger target and has a greater severity.

Other scientists are divided over the team’s research. Earth scientist Jay Melosh of Purdue University said he found that the number of craters was too small to prove any important point. But Avi Loeb of Harvard University agreed with the team’s findings.

Modern humans may not have existed without great extinctions of space rocks, Loeb wrote in an email. Most scientists believe that dinosaurs and many other animals became extinct after a huge space rock crashed in Central America about 65 million years ago.

“This shows how arbitrary and fragile human life is,” he wrote.

I’m Pete Musto.

Seth Borenstein published this story for the Associated Press. Pete Musto adapted it for VOA Learning English. Hai Do was the editor. We want to hear from you. How concerned about the asteroid crashed? Write us in the comments section or on our Facebook page.