(ORDO NEWS) — Scientists have found that they still underestimated the diameter of the celestial body, during the fall of which the largest impact crater on our planet, Vredefort in South Africa, was formed.
Today, 190 impact craters have been identified on the Earth‘s surface . The largest of them is the South African crater Vrederfort, whose diameter is estimated at 250-280 kilometers.
It was formed as a result of the fall of a celestial body about two billion years ago, which makes it also one of the most ancient on the planet.
Previous calculations showed that it could be an asteroid with a diameter of 10-15 kilometers, moving at a speed of 15 kilometers per second.
However, new work by scientists from the University of Rochester in the United States showed that we greatly underestimated its size.
Judging by these data, the celestial body gained 20-25 kilometers and crashed into the Earth’s surface at a speed of up to 20 kilometers per second.
Over the past billions of years, erosion and other geological processes have almost erased the outlines of Vredefort.
Most likely, during this time it became somewhat smaller, but initially it could reach almost 300 kilometers in diameter.
In addition, most of its area today is occupied by agricultural land, which makes it even more difficult to estimate the true size of the crater, and hence the body that left it.
In their work, American scientists relied on new data on its outlines, and also used the iSALE model, which makes it possible to simulate impact (shock) events.
Calculations showed that a 15-kilometer body at a speed of 15 kilometers per second could create a crater no more than 172 kilometers in diameter.
To create a large crater at a speed of 15 kilometers per second, the asteroid had to reach 25 kilometers in diameter or move much faster.
Scientists also used these figures to study how the mass thrown out by the impact of a celestial body was subsequently distributed.
Based on the characteristics of this layer, as well as relying on their model, the authors of the work showed that at the time of the fall of the asteroid, this area was located at a distance of only 2000-2500 kilometers from it – much closer than today.
New estimates make this celestial body much more significant than even the famous asteroid, the fall of which is associated with the Chicxulub crater and the Cretaceous-Paleogene extinction event, which resulted in the extinction of all flightless dinosaurs.
“Unlike Chicxulub, the Vredefort impact event did not leave traces of a mass extinction, since at that time there were only single-celled living organisms and there were no trees.
However, its impact on the global climate could be even more significant than that of Chicxulub,” explained Miki Nakajima.
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