About 66 million years ago, an asteroid estimated to be 9.6 kilometers wide struck Earth. This asteroid collision triggered a series of catastrophic events that resulted in the extinction of dinosaurs. Now, scientists are revealing where the object came from.
According to recent research, the collision was caused by a giant dark primitive asteroid from the outermost part of the main asteroid belt of the solar system, located between Mars and Jupiter. This area is home to many dark asteroids.
The definition of dark here means that space rocks have an arrangement of chemicals that make them appear darker, reflecting very little light compared to other types of asteroids.
"I have a suspicion that the outside of the asteroid belt. That's where dark primitive asteroids, may be an important source of terrestrial impact," said David Nesvorný, a researcher from the Southwest Research Institute in Colorado, who led the study Wednesday (11/8/2021 ).
Clues of objects that wiped out the non -bird dinosaur era have been found buried in Chicxulub crater, a 145km -diameter hole in Mexico’s Yucatan Peninsula. This hole is an object collision container.
Geochemical analysis of the crater has shown that the affected objects are part of a class of carbon chondrites, a group of primitive meteorites that have a relatively high carbon ratio and are likely to have formed early in the history of the solar system.
Based on this knowledge, previous scientists have tried to determine the origin of the impactor, but many theories eventually fall apart over time. Researchers suspect the impact came from a family of asteroids inside the main asteroid belt. However, follow -up observations of the asteroids found that they did not have an exact composition.
Another study, published in February in the journal Scientific Reports, suggested the effect was due to long -term comets. But then the research was attacked.
In a new study, published in the journal Icarus, researchers developed a computer model to see how often major belt asteroids escaped to Earth and whether the escape could be credited with causing an accident that ended the dinosaur era.
Based on a simulation model spanning hundreds of millions of years, it appears that the thermal forces and gravitational pull of planets periodically throw large asteroids out of the belt. On average, asteroids more than 9.6 kilometers wide from the outer edge of the belt are thrown toward collisions with Earth once every 250 million years.
These calculations make such events five times more common than previously thought and are consistent with evidence of the Chicxulub crater that formed 66 million years ago. This is the only known impact crater produced by an asteroid of this size in the last 250 million years.
Further, the model looked at the distribution of ‘dark’ and ‘light’ impacts in the asteroid belt and showed half of the asteroids released were dark carbon chondrites, corresponding to the type suspected of causing the Chicxulub crater to form.
"This is a very good paper. I think they make a good argument as to why Chicxulub's impact might have come from parts of the solar system," commented Jessica Noviello of the University Space Research Association at NASA's Goddard Space Flight Center who was not involved in the research.
In addition to possibly explaining the origins of the Chicxulub crater, the findings also help scientists understand the origins of other asteroids that have struck Earth further in the past. The two largest impact craters on Earth, the Vredefort crater in South Africa and the Sudbury Basin in Canada, are of unknown origin. The results of this study can also help scientists predict where large -impact objects will come from.
"We found that about 60% of major terrestrial imports come from the outside of the asteroid belt, and most asteroids in that zone are dark or primitive. So there's a 60% chance (as much as 3 out of 5) that the next one will come from the region the same. "Nesvorn.
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