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WASHINGTON DC: According to a new study, the number of asteroids colliding with the Earth and the Moon has increased threefold over the past 290 million years.
The study, published in Science, is based on a major study involving the University of Southampton.
Scientists have for decades tried to understand how fast asteroids hit Earth. They have generally done studying the craters and dating the rocks that surround them. However, the problem is that many experts have assumed that the oldest craters disappeared due to erosion and other geological processes.
However, the new study revealed that one could learn a lot about the history of the impact on the Earth by studying the Moon.
The researchers believe that both bodies are affected in the same proportion over time. Moreover, according to scientists, the Moon is immune to processes such as plate tectonics that are progressively destroying craters on the Earth.
William Bottke, an asteroid expert at the Southwest Research Institute in Boulder, Colorado, and co-author of the document, said: "The only obstacle to this operation was finding a precise way to date the large craters on the Moon. "
The research allowed the team to study the Moon's surface using thermal data and images collected by NASA's Lunar Reconnaissance Orbiter (LRO), to determine the age of the the lunar clientele. The NASA thermal radiometer showed scientists that the Moon's surface was giving off heat, with larger rocks giving off more heat than a thinner lunar surface.
The article's co-author, Rebecca Ghent, has calculated the rate at which moon rocks break down in the ground and revealed a relationship between the amount of large rocks near a crater and its age. Using the Ghent technique, the team has compiled the ages of all lunar craters aged less than a billion years old.
According to scientists, younger craters tend to be covered with more rocks and rocks than older craters. This is due to the fact that rocks ejected by an asteroid attack collapse for hundreds of millions of years by a constant shower of tiny meteorites.
Comparing the ages and number of lunar craters to those of Earth, they made the remarkable discovery of their extreme similarity, challenging the idea that the Earth had lost so many craters. "This means that the Earth has fewer old craters in its most stable areas, not because of erosion, but because the impact rate was less than 290 million years ago" said Bottke.
Dr. Thomas Gernon, Associate Professor of Earth Sciences at the University of Southampton, and co-author of the study, added, "Show that fewer craters on Earth mean fewer impacts. that losses due to erosion pose a formidable challenge ".
Gernon added a series of unlikely proofs to piece together the story. The long extinct diamond-bearing volcanoes called kimberlite pipes that extend a few kilometers below the surface on stable ground are largely intact. This indicates that large impact craters formed during the same period and on the same terrain should also be preserved. This explained the similarity of crater recordings of Earth and Moon impact, and helped the team establish that crater rarity formed 290 million years ago is due to the fact that fewer asteroid strikes took place before.
The team's work found that the rate of crater formation over the past 290 million years was two to three times higher than during the 700 million years ago. previous years.
The team's Earth-related discoveries have implications for the story of life – which is punctuated by major extinction events and evolution. fast new species. Although extinction events may have many causes, the team points out that the impact of asteroids has probably played a major role. In particular, dinosaurs proliferated about 250 million years ago and "as a species, they were particularly vulnerable to significant impacts early on, even more so than earlier animal groups. ", says Gernon.
"It is perhaps fair to say that the dinosaurs had a destiny of their own: their fall was somewhat inevitable given the influx of large space rocks colliding with the Earth," concluded Gernon.
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