There is no need to look far away from the traces of meteorite impacts that riddled our world. There is a very good source that gives us a record of our cosmic history, only 385,000 kilometers away.
Researchers from the University of Toronto would have thought so, using a new Moon tracking satellite launched by NASA. Their data seems to rewrite the ancient history of the Earth! You ask why?
A rare occurrence of meteorites that hit Earth and left behind a crater, which ranged from 290 million years ago to 650 million years ago; this was attributed to the disappearance of craters from the distant past, with erosive effects of various geological processes, particularly erosion. However, Sara Mazrouei, who has just completed her PhD in Earth Sciences, and Rebecca Ghent, a professor at the same department, do not say so. The study of the pair shows that the number of meteorite impacts affecting the Earth and the Moon has risen by 2.6 times since 290 million years ago, and that the rarity of craters older than 290 million years on Earth is not caused by geological erosion but by the proportional scarcity of these impacts. What does all this mean and why is it important?
In fact, the story is locked up by NASA’s 2009 surface tracking device Lunar Reconaissance Orbiter (LRO). One of the features of the LRO is the mapping of all surface craters of more than 1 billion years in diameter and more than 10 km in diameter. In doing so, the relevant component of the vehicle (a radiometer called Diviner) determines the age of wear of the young craters by measuring the heat emitted from the surface of the Moon. On the moon night, large stones emit more heat than fine-grained soil / rock fragments. This makes it possible to distinguish the coarse particles from the fine-grained ones in thermal images. Based on this information, researchers spread to the surface during meteor impacts, and then were able to identify and date fragments of rock scattered on the shores of the crater, broken by meteor showers lasting for tens of millions of years. Thus, the actual age of the lunar craters of unknown origin was revealed. In the second and most important stage, when compared with the age of craters on Earth, it was found that both groups were formed as a result of the same meteor bombardment story. In essence, something changed in space about 290 million years ago, and the Moon and Earth found themselves under the same meteor shower. So what changed?
In fact, it is not known, but let us convey the most plausible possibility that researchers have said: The meteor belt between Mars and Jupiter’s orbits is known to have occurred more than 300 million years ago. The meteors that reach the inner parts of the solar system and bomb the Earth and the Moon can be debris from these collisions.
We come back to dinosaurs
The team that published the results of their work in the January 18 issue of Science magazine is not the first to say that meteorite impacts fluctuate, but it is the first team that can show it statistically and put it into numbers. There is another element that makes the study important: the relationship between meteorite impacts and the history of life on Earth. The period in which meteorite impacts targeting the Earth and Moon intensify corresponds to the end of the Paleozoic period, the beginning of the period in which species known from dinosaurs to mammals emerged, with the language of geological eras. But we know from the fossil record that this 300-million-year-old universe has also been interrupted by mass extinctions many times, followed by the rapid evolution of new species. Of course, these fluctuating processes may be associated with different ground and climate events. But meteorite impacts are not independent of them. As a matter of fact, the end of the Permian extinction (250 million years ago), which was supposed to have occurred during the period when the impacts were said to have intensified, was the most severe of the known mass extinctions, and erased more than 95% of life from the earth. This was followed by the end of the Triassic extinction (200 million years ago) and the end of the Cretaceous extinction (66 million years ago), which closed the dinosaur era and opened the door to small mammals. So we can repeat the question that Rebecca Ghent asked: mi Can there be a direct link between the calculated frequency of meteorite impacts and the long-lived events on Earth? Acak This will be the subject of further research.