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You may have come across a crazy theory that we are descended from extraterrestrials. In a way, this idea can be right.
That does not mean that we were raised by little green men who live in science fiction fiction, of course. According to a study conducted by researchers at Rice University in Texas (USA) and published Wednesday by the scientific journal Science Advances, a global collision 4.4 billion years ago brought to our planet the elements keys to the emergence of life.
"Our study indicates that the Earth has acquired its share of the essential elements of life at a very advanced stage of its accumulation, probably by the same impact as that which formed the Moon," said the geologist and a specialist in the sciences of the planet, Damanveer. Grewal.
In astrophysics, accretion is the name given to the accumulation of material on the surface of a star due to the action of gravity.
"While the Earth has a long history of growth, spaced by accumulations of millions of years, gigantic impacts must have played a key role in the origin of life on our planet", he continues.
"The key elements of life"
In an interview with BBC News Brazil, Rajdeep Dasgupta, a geologist and planetary scientist, recalled that "carbon, oxygen, l? Hydrogen, nitrogen, sulfur and phosphorus are the five key elements for life as we know it. "
" Without carbon, nitrogen and sulfur, it is impossible to produce hydrocarbons, amino acids and proteins necessary for life. " We are therefore focusing on the origin of some of these fundamentals, "he explains." We can not exclude the possibility that the Earth has acquired the necessary dose of essential elements of life without have suffered episodes of gigantic impacts, but the relative inventory of carbon, nitrogen and sulfur in the accessible part of our planet indicates its origin through a gigantic impact, as suggested in our study "
As researchers have become more and more contextualized, it has long been known that rocky planets, like the Earth, contain very little volatile matter." The calendar and mechanism that brought Earth to acquiring such elements arouse exciting debates, "said Dasgupta." Our scenario may explain this phenomenon in a manner consistent with all the geochemical evidence. "
The researchers compiled the results of the study. a series of experiments conducted at high temperature and under high pressure in a specialized laboratory of Rice University. There, they simulated geochemical reactions that had to occur on Earth billions of years ago.
They started from an already existing theory that the volatile substances of the Earth would come from a collision with a planet whose nucleus was rich in sulfur, called "donor planet".
"Our main challenge was to explain why the Earth's surface has a much higher carbon to nitrogen ratio than primitive meteorites," says Grewal. "Our experiments have shown that if the core of a rocky planet is rich in sulfur, the carbon is expelled in a greater proportion than that of nitrogen".
In these simulations, the scientists concluded that for this, such a "donor planet" should be the size of Mars. A gigantic collision, therefore. Of this size, everything seems to have been the same collision that formed the Moon.
The theory most widely accepted today by the scientific community to explain the formation of the moon is that called the hypothesis of great impact. Introduced in 1975 by researchers from the Tucson Global Institute and the Harvard-Smithsonian Institute of Astrophysics, the theory concludes that there are 4.4 billion years ago a planet the size of Mars called Theia was hit by The Earth.
"Planetary impacts occur throughout the history of a solar system," says Professor Dasgupta. "The planetary impacts have been much more common during the first tens of millions of years of the solar system's history." At this time, the protoplanetary disk was still evolving and orbits of various bodies were still being established. "
The giant collision at 40,000 kilometers at the time would not have been frontal, but lateral.As a result of the impact, a large amount of material collapsed, forming the Moon , and 90% of the lunar composition would come from the ancient planet Theia.
The theory states that the material that gave birth to the Moon has stabilized at some 22,000 km from the Earth 27 hours after the collision – the current distance between Earth and Moon is 385 000 km.
The theory most accepted by the scientific community for explain the formation of the Moon dates from 1975 and called the hypothesis of great impact – Photo: Reuters / Baz Ratner
The rest of Theia has been incorporated into his land. And, as scientists have confirmed in the laboratory, this material has created conditions conducive to the emergence of life on the planet. "The conclusion that the volatile body of the Earth comes from a planet the size of Mars comes from the combination of our experimental measurements, where we show how carbon and nitrogen can be separated from each other. one of the other when forming the nucleus of a planet with a sulfur – rich nucleus, "says Professor Dasgupta. "These simulations have proven that the greatest likelihood of obtaining carbon, nitrogen and sulfur is when the colliding body size is that of a large planet."
To arrive at such a conclusion, the scientists carried out a computer modeling. About 1 billion different scenarios were executed, with known conditions in the solar system, until the results indicated a more possible version of what was really going to happen. "So we discovered all the evidence – isotope signatures, carbon-nitrogen ratio, and total amounts of carbon, nitrogen, and sulfur on Earth – consistent with the impact of Moon formation. : a Mars-sized planet with a sulfur-rich nucleus, "he says. Grewal.
"We performed more than a billion numerical simulations to calculate the composition and mbad of the planet that had to supply the volatile substances to Earth." Our simulations predicted a Mars-sized planet with specific characteristics. and the composition indicates the moment that coincides with the formation of the moon, "sums up the researcher.
" This also explains why the Earth and the Moon are geochemically similar, "Dasgupta says.
Dasgupta says that it is helpful to understand how the life formed on Earth can help in the search for similar phenomena on other planets. "The study indicates that a rock planet similar to the Earth is more likely to occur. 39; acquire essential elements of life if it is formed and grows as a result of giant impacts with planets whose composition is different, "he says.
There is no doubt that this is the only way to behave. is a tip for watching telescopes in the air.
