The moon could arise as a result of a single collision of the Earth and a protoplanet the size of Mars, and in the course of a series of small collisions of planetary embryos with the Earth, which would explain oddities in the isotopic composition of the moon.
If the Moon were formed during this series of collisions, then it will resolve the issue with the isotopes very original way. Its formation is similar to what happens when an artist mixes paint on the palette – the more colors you mix, the less changes the final result and the more it will look like dark brown paint, says Gareth Collins (Gareth Collins) from Imperial College London (UK).
Secrets Of The Moon
The last 30 years, it was assumed that the Moon formed as a result of collision theis, protoplanetary body, with the embryo of the Earth. The impact resulted in the ejection of matter theis and proto-Earth to space, from this material formed the Moon. Theory of collision of proto-Earth with a large celestial body explains well the mass of the moon, the low iron content therein, and other parameters.
However, this clash is a significant part of the material constituting the moon was supposed to bring hypothetical Theia. In its composition it had to be different from the Earth, as different from her most celestial bodies in the inner Solar system, including terrestrial planets and asteroids. But in fact, the composition of the Earth and moon are very similar, down to the same proportion of isotopes of many metals and other elements.
Recently, planetary scientists have proposed a rather unusual solution to this problem – the so-called hypothesis of the planet-Yuly. According to her, the young Earth was spinning very quickly and it lay on its side, like Uranus, and the collision with Theia had to slow her down and turn her axis. Such a scenario has in principle the right to life, but it is extremely unlikely that forcing planetary scientists to look for other options of birth of the moon.
Hagai Perets (Hagai Perets) from the Technological Institute of Israel in Haifa and his colleagues proposed an alternative explanation for the lack of differences in the proportions of isotopes in the rocks of the moon and of the Earth, assuming that the companion of our planet could not form in one sitting, but in parts.
If the Earth was faced not with one Theia the size of Mars, with a whole set of small protoplanets, then the speed of rotation of our planet and the consequences of a collision may not be as large, which requires a classic scenario of the formation of the moon. Every time when such a moon crashed into the Earth, they threw part of its matter into orbit, where it merged with the already existing Moon formed after collision.
Guided by this idea. Pepper and his colleagues have calculated the consequences of a collision of the Earth with several such embryos and tested whether the Moon to grow to its present size and to achieve the desired ratio of isotopes in a similar way.
As it turned out, such a scenario is indeed possible – successive fall and the destruction of about 20 small protoplanetary bodies whose mass is around 1-10% by weight, will be enough to form the moon in its present size and with a modern composition. On the other hand, if at least one mini-Moon escape from the Earth, then the formation of the moon would require a much larger number of nuclei of the planets.
Such a hypothesis might seem even less realistic than the idea of planet-Yuly, however in the first era of life in the Solar system it was inhabited by thousands of large and many small nuclei of the planets, many of which were catapulted into space or displayed on a collision course with Earth and the other planets at that moment when Jupiter and Saturn began their movement towards the Sun. It is possible that some of them crashed into proto-Earth and created the moon.