How was the moon formed? Five strong theories about its origin

the moonThe most easily observable celestial body dearFor more than 4,000 million years, diurnal and nocturnal cycles have accompanied us. Looking at the moon in the sky, it looks as old and beautiful as it always has. But,How it came to be First is ours Natural satellite That goes around land At an average of 385,000 kilometers?

with a The diameter is less than 3,500 km And a cratered surface, this rocky material betrays scientists looking for it Various theories.

In addition to being an unusually large satellite, the Moon orbits our planet A highly inclined orbit As for our equator, there are significant differences in its chemical composition and physical structure. Although the planets are at least several thousand times larger than their satellites, the Earth is eighty times larger than the Moon.

Until two decades ago three theories were proposed to explain the origin of the Moon, none of which was fully accepted or rejected. Then came two more solid, but sometimes questionable ones.

1-Deficiency: According to the so-called rift model, the Earth originally formed on its own, but then rotates very rapidly, orbiting itself once every four hours. This rapid cycle occurred A piece of Earth broke off, and in turn split off, forming the Moon and neighboring planet Mars. A problem with this model is that it cannot explain the properties of the Moon’s orbit.

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2-Joint Birth: Perhaps the most naturalistic model proposes co-birth, Moon and Earth They were born simultaneously as two separate entities. But this theory cannot explain, among other things, why the Moon does not have an iron core when the Earth has an iron core.

3-Catch model: A third principle holds that The two objects formed separately at the beginning of the solar system and the Moon, as it approached Earth, was captured by our planet. However, the conditions for this capture are very difficult to meet, and this model cannot explain the Moon’s low iron content.

4-A big impact: The findings of a new study of lunar rocks brought back to Earth by NASA 50 years ago A new theory says that The Moon was formed after another planet collided with the young Earth Then it melted billions of years ago.

Let’s take a deeper look The Great Impact Theory In which it is speculated that when Earth was a young planet And it began to evolve Hit by another rising planet called Thea, located very close to its orbit. The collision caused the two planets to temporarily separate into globes of gas, magma, and chemical elements that reformed into the bodies we know today as Earth and the Moon. Research by Simon and Gargano further corroborates this theory.

“There’s a big difference between the modern elemental composition of the Earth and the Moon, and we wanted to know why. Now, we know that the Moon was very different from the beginning, and that’s because ‘Huge impactNASA planetary scientist said. Justin Simonwho along with his fellow graduate Tony GarganoThe duo, from the agency’s Astronomical Materials Research and Exploration Sciences Division at the Johnson Space Center in Houston, led the research and recently published the results in the journal Proceedings of the National Academy of Sciences.

Researchers focused on size and look Types of chlorine found in rocks. They chose this element because it is volatile, meaning it evaporates at relatively low temperatures, and tracking it is useful for understanding planet formation. Chlorine exists in two abundant and stable forms: light and heavy. These terms are used to describe chemicals Variations within it Atomic structureAlso called isotopes.

What they found was Moon rocks contain high amounts of heavy chlorine, while Earth rocks are rich in light chlorine. Heavy tends to resist change and remain constant, but light is more reactive and sensitive to different forces. In In the giant impact model, spots on the Earth and Moon initially contained a mixture of light and heavy chlorine. But as the planets reunited, the larger Earth dominated the growth processes and attracted lighter, more volatile chlorine to itself, leaving the Moon devoid of light chlorine and other volatile elements. Based on measurements taken by scientists, this appears to be the case.

5-Multiple Effects: Another theory says that The Moon may have been formed by a series of large impacts. Rather than being the result of a giant collision, this explains why it was made of Earth-like material and not a mixture of terrestrial and other planetary debris. Those impacts would have put millions of tons of debris into orbit, which would have coalesced to form the satellite that orbits us.

In the event of a major accident, most of the materials would be formed The moon came from Earth, not an attacker (the object that collided with it) or a combination of both was the same. “Both scenarios are possible but unlikely,” says a study published by the journal in 2017 Natural Earth SciencesUnlike what happens on Earth and the Moon, the meteorites and asteroids that populate the Solar System vary greatly in their chemical composition.

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A panel of experts from Weizmann Institute of Scienceof Israeland from Imperial College of London Performed various numerical simulations of large planetary bodies when the Earth was in its formation period. In these simulations, the impacts created debris discs, most of which were composed mostly of terrestrial material.

After each impact, the debris disks accreted to form a small moon, which migrated to merge with the growing moon, the authors suggest. According to the study It took about 20 impacts to form a small moon to form Earth’s satellite. The authors suggest that these types of impacts between the Earth and other large celestial bodies capable of forming small moons are “common” in the inner solar system to form moons.

Theory today Brutal impact Occurred 4000 million years ago And consensus Creates about how the moon might have formed. This month, experts backed up the theory’s arguments New researchThey are one of them A very detailed computer simulation Created by him Institute for Computational Cosmology at Durham University. This new”Instant satellite view”, implying that the proto-moon was less molten during its formation and that most of it formed immediately after a giant impact with Earth.

Even this theory of rapid formation would suggest a different internal structure to the Moon, which would provide an explanation Some interesting Earth-like features found in lunar samples.

High-resolution results obtained through the impressive computing power of the DiRAC memory-intensive service CosmaLocated at Durham University in England. It showed the outer shell of the moon filled with material from Earth.

“This formation pathway may help explain the similarity in isotopic composition between lunar rocks returned by the Apollo astronauts and Earth’s mantle. The thickness of the lunar crust may also have observable effects.This will allow us to further pinpoint the type of collision that took place,” said Vincent Ake, a physicist and co-author of the research at Durham University.This is a statement.

Additional computational power revealed that low-resolution simulations may miss important features of large-scale collisions. With high-resolution simulations, researchers can detect features that were inaccessible in previous studies. If most of the Moon formed immediately after the giant impact, it would also mean that the Moon had less melt during formation than traditional theories in which the Moon grew inside a debris disk around Earth. Depending on the details of subsequent solidification, these theories should predict different internal structures for the Moon.

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