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Study Results: Earth Is Hit By An Asteroid The Size Of A City Every 15 Years

Harianjogja.com, JAKARTA – A new study finds that asteroids the size of a city, like the one that wiped out the dinosaurs, are hitting Earth more often than previously thought.

Research presented at the Goldschmidt geochemistry conference last week suggested that roughly every 15 million years, the evolving planet Earth would be hit by a piece of rock the size of a city, or even a larger province.

This period of impact, which occurred between 2.5 and 3.5 billion years ago, was studied by seeing the planet in regular turbulence, with its near-surface chemistry undergoing dramatic changes that can be tracked in rocks on the ground even today, researchers say. launch Space, Friday (16/7/2021).

In the study, Simone Marchi, a principal scientist at the Southwest Research Institute in Boulder, Colorado, and her colleagues noticed the presence of so-called spherules, tiny bubbles of vaporized rock that are hurled into space by each asteroid impact, but then solidify and solidify. fell back to Earth, forming the thin layer geologists see in bedrock today.

The team developed a new method to model the effects of asteroid impacts in terms of their ability to generate spheres and affect their global distribution. The bigger the asteroid, the thicker the spherical layer in the rock should be. But when the researchers looked at the actual number of spherules in various bedrock layers and compared them with estimates of past asteroid impacts, they found the two values ​​did not match.

“We find that current early Earth bombardment models greatly underestimate the number of known impacts, as recorded by the spherical layer,” Marchi said in the statement. “The actual impact flux could have been a factor of 10 times higher than previously thought in the period between 3.5 and 2.5 billion years ago.”

That past asteroid strike may also have affected the young planet’s oxygen levels and ability to support life.

“We found that oxygen levels would fluctuate drastically during periods of intense impact,” Marchi said. “Given the importance of oxygen to the development of the Earth, and indeed to the development of life, its possible relationship to the collision is very interesting and deserves further investigation. This is the next stage of our work.”

According to Rosalie Tostevin, of the University of Cape Town, who was not involved in the research but specializes in ancient geology, several chemical markers suggest the presence of an oxygen “smell” in the early atmosphere, before the permanent rise that occurred around 2.5 billion years ago.

“There is considerable debate around the importance of this odor, or indeed, whether it occurs at all,” Tostevin said in a statement. “We tend to focus on Earth’s interior and the evolution of life as a control on Earth’s oxygen balance, but bombardment with rocks from space provides an interesting alternative.”

Rocky bodies without an atmosphere, such as the moon, carry detailed records of past asteroid impacts. On a planet like Earth, with its varied patterns of weather and geological activity, traces of many past impacts have long since been erased. It took until the late 1970s for scientists to discover the Chicxulub impact crater in Mexico. It took several more years for them to identify this impact as the cause of the extinction of the dinosaurs.

“This massive impact will certainly cause some disruption,” said Tostevin. “Unfortunately, very few rocks from the past have survived, so direct evidence for the impact, and its ecological consequences, is uneven. The model proposed by Dr. Marchi helps us to better understand the number and size of the collisions in the early Earth.”

Source: Bisnis.com

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