Earth’s gravity in the process of interaction with the newborn moon was the reason that the most heavy rock with a complex chemical composition gathered on the near side of the Moon, while the lungs of minerals primitive type moved to the back of the satellite, as reported by astronomers in the information published in the journal Nature Geoscience .
In contrast to the visible side of the Moon with prevailing on the plains of her back covered with a large number of hills and craters. In addition, recent studies have gravitometricheskie scientists argue that the visible region of the moon pretty much harder than its opposite half. Such asymmetry of the satellite of our planet has been explained by astrophysicists as a result of uneven cooling and solidification of "new-born" of the Moon, the gravitational influence of the Earth or the intensity of the "bombing" of the back.
A group of Japanese planetary scientists led by Makiko Ohtake Institute of Space Science in Kanagawa JAXA decided to find an explanation for the anomalies in the mineral content of the lunar rocks, exploring in detail the samples obtained during the expedition vehicle "Apollo" and by analyzing geological data, obtained U.S. probe Lunar Prospector as well as the Japanese unit "Kaguya".
Researchers have suggested that the history of the formation of the moon can be recovered, taking into account the rate of cooling and solidification of the magma ocean on the surface on each of its sides.
To this end, the researchers performed an analysis of the chemical composition of lunar anorthosite - rocks of magmatic origin, containing calcium, aluminum, silicon, and many impurities minerals with lots of iron. The analysis Ohtake and his colleagues took into account mainly the concentration of magnesium, which is in the depths of the moon, because the proportion of magnesium in the rock determines the degree of "sophistication." The smaller magnesium atoms in the mineral, the higher its chemical complexity.
The study authors used data that were obtained spectrometer "Kaguya" to design a map of the concentration of the metal in the lunar rocks. As it turned out, almost all rocks located on the near side is relatively small percentage of magnesium, and a significantly increased was noted on the reverse side.
According to scientists, such distribution of minerals occurred as a result of two processes: all the rocks on the Moon, perhaps frozen earlier than on the visible side of the planet, or less dense rocks on the near side of the Moon mixed with heavy rocks that are in the lower layers of "Lake "magma.
The researchers believe that the first process is more likely. According to them, he came in sight of interaction of gravity of the Earth and Moon’s newborn, which raised the temperature on the visible half of the satellite.
As a consequence, there was a convective "conveyor belt", is easily tolerated minerals in a frozen state with the visible side to the back, where less dense, rich in magnesium rocks accumulated in the equatorial region. This mechanism is comparable to the process of boiling water in a kettle or heating air heating panels.
As a result, the visible part of the moon appeared "hard" crust formed by the lower igneous rocks, and on the other side of the formed track. Perhaps this is the explanation of why the side of the moon that is closest to the Earth, is somewhat heavier than the back half, as the scientists concluded.