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Carbon chondrite found in impact craters in many places on Earth confirms Harvard scientists’ theory of what happened 66 million years ago
A team that includes two astronomers from Harvard University has been able to enrich the research debate on the origins of the comet that caused the end of 3 quarters of life on Earth about 66 million years ago, and the possibilities similar keystrokes in the future.
The fringes of the solar system
The study – published in the journal Nature, Scientific Reports and Harvard University issued a press release on the matter on Feb.15 – said statistical analyzes and gravitational simulations conducted by the team showed that what struck the Earth came from the Oort cloud. (Oort Cloud).
And the Oort cloud is the outer limit of our solar system, and it takes a spherical shape that envelops the entire solar system, and its inner limits start at a distance of 300 billion kilometers from the sun, and it was named d ‘after German astronomer Jan Auer, who began its existence in 1950.
Scientists assume that this cloud contains nearly two trillion objects with a diameter greater than a kilometer and that their orbits around the sun are millions of years old, and the cause of this region is believed to be the stresses and the thrusts between the planets in the early stages of formation of the solar system, which pushed relatively small objects.
The Oort cloud which envelops the solar system in relation to the orbits of the planets, and the orbit of Pluto in yellow (NASA)Coming from behind
The prevailing assumption was that the huge boulder that hit Earth about 66 million years ago in an area now known as the Yucatan Peninsula in Mexico was an asteroid from the asteroid belt between Mars and Jupiter.
But simulations by Harvard researchers Avi Loeb and Saraj Amir showed it to be a long-range comet coming from the Oort Cloud, then receiving a boost from Jupiter’s gravity that caused it to pass from sun at a close distance, and here the gravitational force of the sun caused the fragmentation of some of its parts.
These little pieces of the comet there gave more statistical opportunity for one of them to fall on the way to Earth, which actually happened, according to the study. What struck Earth, then, was not an asteroid, but a piece of crumbs from a comet estimated to be 10 to 80 kilometers wide.
Astronomers divide comets into two types: one that has an orbit that completes an orbit around the sun in a period greater than 200 years, and this type is called “long-lived comets,” like Hyakutake and Hale-Bopp. The second type will orbit the Sun in less than 200 years, and are called “short-lived comets,” like Tempel and Encke.
According to the study, long-term comets tend in 20% of cases to approach the sun and partially or completely disintegrate, which increases the probability of hitting the Earth 10 times compared to the previous hypothesis, which gives the chance that one of these coins will strike the Earth once every 250 and 370 thousand years.
Ground nozzles
On the other hand, the study showed that the examination of the composition of the rocks in the collision zone in the Yucatan peninsula indicated the presence of a large proportion of carbonaceous chondrite, which is present in greater proportion in the long-term comets versus asteroids in the Asteroid Belt.
This confirms that other craters – which were due to shocks received by the Earth – contained the same material in large proportions, such as the Friedfort crater which formed two billion years ago in South Africa. , which is the largest confirmed crater in Earth’s history, and Zamanshin Crater in Kazakhstan, which is the largest confirmed crater formed in the last million years.
Harvard researchers hope that future studies will examine the composition of lunar craters caused by long-lived comets, to confirm the presence of carbon chondrites in proportions similar to these terrestrial craters, which will help develop our understanding of the deep past. of the Earth, and therefore of its future. with that kind of risk.
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