The versions of the moon's origin are quite diverse: from scientific hypotheses to fantastic assumptions. Nevertheless, many of them are seriously argued, and therefore deserve our attention.
Mega Impact Model
Today in the scientific world, when explaining the origin of the moon, the most popular "collision hypothesis" or "mega-impact model". It is supported by the fact that the Earth used to rotate much faster - it made one revolution around its axis in 2-3 hours, and only after a collision with another cosmic object, thanks to the gravitational interaction of two orbits, its rotation began to slow down. As shown by computer simulations, from a dynamic point of view, such a scenario is quite feasible. However, there is no unanimity within this version. Scientists identify three options.
1. Foreign body
According to one of the theories, the Moon is nothing more than a fragment of a space object that collided with the Earth over 4 billion years ago. And scientists even call this object - the small planet Theia (according to some assumptions the size of Mars). As a result of a powerful blow, the space body turned into a huge cloud of debris, which, once in the earth's orbit, eventually formed into a satellite.
This hypothesis, put forward by two groups of American scientists, successfully explained the iron deficiency on the Moon, in contrast to our planet, and some of the dynamic characteristics of the Earth-Moon system. But there is a weak point in it. Chemical analysis showed the identity of the composition of the lunar and terrestrial rocks.
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2. Fragment of the Earth
According to this version, when it collided with another celestial body, the proto-earth released a substance from which the moon was formed. This is exactly how, according to Harvard University staff, one can explain the similarity of the chemical composition of the Earth and its satellite.
3. Two in one
This hypothesis supplements the previous one, however, it states that as a result of a catastrophic collision, part of the mass of terrestrial matter and the projectile formed a single substance, which was ejected into the near-earth orbit in molten form. This material created the satellite. In this interpretation, the collision occurred before the formation of the Earth's core, which explains the low iron content in the lunar soil.
Centrifugal separation hypothesis
For the first time, the hypothesis of the separation of the Moon from the Earth under the action of centrifugal forces was put forward by George Darwin (son of Charles Darwin) in 1878. According to the supporters of this theory, the planet's rotation speed was fast enough for a fragment of matter to separate from the proto-earth, which later formed the Moon. However, already in the 30s of the XX century, scientists began to treat such an idea with skepticism. They argued that the total rotational moment is insufficient for the occurrence of "rotational instability" even in a liquid Earth.
Capture theory
Recently, a version is gaining popularity, put forward in 1909 by the American astronomer Jackson C, according to which the Earth and the Moon were formed independently of each other in different parts of the solar system. At the moment of the closest passage of the Moon relative to the earth's orbit, a celestial body was captured by gravitational forces.
This appears to have happened during the human period of Earth's history. The legends of many peoples of the world, in particular the Dogons, tell about the times when there was no satellite in the firmament. This hypothesis is also indirectly confirmed by a relatively shallow layer of cosmic dust on the lunar surface.
Artificial satellite
The idea of the artificial origin of the Moon is the most controversial, since the existence of an alien or terrestrial civilization has not yet been proven capable of doing this. Nevertheless, it deserves attention, if only because it was expressed by scientists.
In 1960, researchers Mikhail Vasin and Alexander Shcherbakov, studying some of the characteristics of our satellite, came to the conclusion that it might be of artificial origin. So, given the size and depth of the lunar craters formed during the bombardment by cosmic bodies, they suggested that the lunar crust could be made of titanium, the thickness of which, according to preliminary calculations of Soviet scientists, was 32 kilometers.
“When I first stumbled upon a shocking Soviet theory explaining the true nature of the moon, I was shocked,” writes American researcher Don Wilson. - At first it seemed incredible to me and, naturally, I rejected her. When our Apollo expeditions brought more and more facts to support the Soviet theory, I was forced to accept it."
Strange indicators
Adherents of the theory of "artificial moon" drew attention to the very high ratio of the mass of the satellite to the mass of the Earth - 1:81, which is not typical for the satellites of other planets of the solar system. Only Charon and Pluto have higher indicators, although the latter is no longer considered a planet.
Comparisons of the sizes of satellites are interesting. For example, the largest satellite of Mars, Phobos, does not exceed 20 km in diameter, while the Moon has this figure of 3560 km.
By the way, it is this size of the Moon, which coincides with the diameter of the Sun for a terrestrial observer, that allows us to periodically see solar eclipses.
Finally, the almost perfect circular orbit of the Moon is surprising, while other satellites have it elliptical.
Hollow Moon
It is also interesting that the gravitational attraction of the Moon is inhomogeneous. The crew of Apollo VIII, flying around the satellite, noted that the gravity of the moon has sharp anomalies - in some places it "mysteriously increases."
Paying attention to the data of the American crew (which were classified), as well as the low density of the satellite in relation to its mass, nuclear engineer William Brian stated in 1982 that "the moon is hollow and relatively rigid." A number of later studies have led scientists to speculate that this cavity is artificial. But the researchers also made bolder conclusions, according to which the Moon was formed "in the opposite direction" - that is, from the surface to the core.
Gas and dust cloud
However, in recent years, scientists are not ready to seriously consider the version of the artificial origin of the moon. Much closer to modern scientific views, for example, the "theory of evaporation". According to this hypothesis, significant masses of matter were isolated from the earth's plasma, which, when cooled, formed condensate - it became the building material for the protoluna.
The idea of the artificial origin of the Moon is the most controversial, since the existence of an alien or terrestrial civilization has not yet been proven capable of doing this. Nevertheless, it deserves attention, if only because it was expressed by scientists.
In 1960, researchers Mikhail Vasin and Alexander Shcherbakov, studying some of the characteristics of our satellite, came to the conclusion that it might be of artificial origin. So, given the size and depth of the lunar craters formed during the bombardment by cosmic bodies, they suggested that the lunar crust could be made of titanium, the thickness of which, according to preliminary calculations of Soviet scientists, was 32 kilometers.
“When I first stumbled upon a shocking Soviet theory explaining the true nature of the moon, I was shocked,” writes American researcher Don Wilson. - At first it seemed incredible to me and, naturally, I rejected her. When our Apollo expeditions brought more and more facts to support the Soviet theory, I was forced to accept it."
Strange indicators
Adherents of the theory of "artificial moon" drew attention to the very high ratio of the mass of the satellite to the mass of the Earth - 1:81, which is not typical for the satellites of other planets of the solar system. Only Charon and Pluto have higher indicators, although the latter is no longer considered a planet.
Comparisons of the sizes of satellites are interesting. For example, the largest satellite of Mars, Phobos, does not exceed 20 km in diameter, while the Moon has this figure of 3560 km.
By the way, it is this size of the Moon, which coincides with the diameter of the Sun for a terrestrial observer, that allows us to periodically see solar eclipses.
Finally, the almost perfect circular orbit of the Moon is surprising, while other satellites have it elliptical.
Hollow Moon
It is also interesting that the gravitational attraction of the Moon is inhomogeneous. The crew of Apollo VIII, flying around the satellite, noted that the gravity of the moon has sharp anomalies - in some places it "mysteriously increases."
Paying attention to the data of the American crew (which were classified), as well as the low density of the satellite in relation to its mass, nuclear engineer William Brian stated in 1982 that "the moon is hollow and relatively rigid." A number of later studies have led scientists to speculate that this cavity is artificial. But the researchers also made bolder conclusions, according to which the Moon was formed "in the opposite direction" - that is, from the surface to the core.
Gas and dust cloud
However, in recent years, scientists are not ready to seriously consider the version of the artificial origin of the moon. Much closer to modern scientific views, for example, the "theory of evaporation". According to this hypothesis, significant masses of matter were isolated from the earth's plasma, which, when cooled, formed condensate - it became the building material for the protoluna.
But there is another - a similar idea, put forward in the 18th century. First, the Swedish naturalist Emmanuel Swedenborg, and then the French astronomer Pierre-Simon Laplace, suggested that interstellar nebulae - clouds of gas and dust in outer space - are compressed and condensed into stars and the planets surrounding them. The French scientist also suggested that our satellite could also be formed from this substance.
Russian academician E. M. Galimov has developed a concept that has temporarily gone out of fashion, in which the Moon is the result of "fragmentation of dust condensation." This hypothesis is based on the results of radioisotope analysis of the satellite and the planet, which show that both bodies have the same age - about 4.5 billion years. In other words, both the Moon and the Earth were formed in the neighborhood of matter located at the same distance from the Sun. According to the scientist, the concept of the origin of the Moon from primary matter, and not from the Earth's mantle, is in better agreement with the facts than the "mega-impact model" adopted so far.