Moon

The location of the Moon.
To date, it is the only known artificial satellite of the Earth. It is possible that due to the rapid development of the observational technical base, other, but much smaller, natural satellites of the Earth, which can be classified as asteroids, will soon be discovered.
The Nature of the Moon:
According to the Albedo data.
The albedo of the visible side of the moon is 0.073. In areas dominated by lunar seas (see here), it is smaller, and continents (see here) are larger, but in general, the surface of the Moon (see this page) reflects a little more than seven percent of the light, and it is difficult to imagine that the silvery disk of the Moon is actually almost black. At the same time, such an apparent contradiction can be resolved if we take into account the fact that the Moon is a reflection of a powerful stream of solar radiation and even 0.073 of its share is quite large.
The state of the atmosphere.
The Moon has no general atmosphere. On the sunlit side of the Moon, near its surface (see here), a faint layer of gas was detected. Ten million times more rarefied than the Earth’s atmosphere. This gas contains atoms that were introduced into the regolith by the solar wind and were named: H, Ne, O, Ne, Ar, as well as those released from the lunar surface during meteorite impacts affecting the Earth’s surface and during the bombardment of the regolith by cosmic rays. At night, the gas concentration decreases by another ten thousand times, which is due to the freezing of most of the gas in the regolith.
The inner side.
The Moon’s relation to the Earth is always the same: it always looks at the Earth with the same hemisphere, which is called its visible side. The reason for this is that the periods of the Moon’s revolution around the Earth and rotation around its own axis completely coincide. Read more about the reverse side here.
Wine bowls, or craters (from the Greek. krathraV – krateras – wine bowl).
Popular terms for craters are ring mountains or ramparts with a small slide that is located in the center. At the moment, they have a diameter from a few centimeters to 235 kilometers, which has the Grimaldi crater. The length and height of the ring mountains of large craters ranges between 300 and 7000 meters. However, the ratio of the diameters of many craters and the height of their ring shafts is such that an observer located in the center of the crater will not be able to see the surrounding hills, since they are hidden behind the lunar horizon.
Small craters were formed as a result of bombardment by meteoroids, while large ones were formed as a result of bombardment by larger bodies: asteroids or cometary nuclei. Subsequent volcanic processes and the formation of large craters occurred under the influence of the impact of larger bodies.
The old craters, which were relatively young, underwent less destruction and retained their original shape better. Some of them have the opportunity to observe the rays of light that are clearly visible during the full moon, which radiate radially from them.
There are more than three hundred thousand craters on the surface of the moon, measuring more than a kilometer.
A straight slope (from Latin libratio – swing).
Libration is a small fluctuation that occurs when the Moon moves in orbit. They have geometric and dynamic reasons. These geographical reasons are related to the fact that due to the ellipticity of its orbit (see Orbit, elliptical), the Moon, according to Kepler’s second law, rotates around the Earth at different speeds in different parts of it. Due to the constant speed of rotation of the Moon around its axis, an observer on Earth has the opportunity to observe from the east, then from the west, part of what is inaccessible to an earthly observer in other conditions. Due to the fact that the axis of the Moon’s daily rotation is inclined to the plane of its orbit (see Day), it became possible to “inspect” its opposite hemisphere from different sides, including from the north and south. Fluctuations caused by dynamic causes can also be observed on the Moon. This makes it possible to observe 0.6 of the Moon’s surface from Earth, rather than 0.5, as it would be in the absence of libration.
From English, mass concentration is the concentration of mass.
Formations present in the Moon’s lithosphere near its surface that cause gravitational (see physical, gravitational field) anomalies are called mascons. As a result of the discovery, they were localized due to disturbances in the motion of artificial satellites of the Moon. Basically, the mascons are located under the lunar seas (see here), which have a rounded shape.
It is believed that their origin is connected with the impacts of huge cosmic bodies, which in turn caused huge depressions in the lunar crust, reaching several kilometers. Following this, geological processes began. At the bottom, a denser and hotter mantle, which was melted more than the crust, pushed up the bottom of the geological depression formed by the impact, forming a bulge lens under it, consisting of the substance of the raised mantle. Part of the mantle substance on the surface rose to the surface in the form of lava and filled the rest of the depression. Based on this, in some areas of the lunar crust, places were found where its density was higher than in other places.
There is a possibility that mascons are present on Mars and Mercury.
Equipment.
Continents are those areas of the Moon’s surface that have a light shade. They are about 4.5 billion years old. They are surrounded by craters and mountain systems, the height of which is 7-8 kilometers. These lands were formed by ancient lunar rocks that do not contain traces of rock eruption, so they have preserved all traces of the effects of cosmic factors: meteoroids, dust, solar wind and cosmic rays.
Sea shores.
The seashores are flat and dark areas of the surface that do not have large craters. At the same time, due to the existing conditions on the Moon and their physical characteristics, they cannot contain a drop of liquid water. These places were formed by molten rocks that once flowed out of the bowels of the Moon – basalts that hid previously formed craters. The age of the seas is no more than 3.5 billion years. The surface of this basalt layer in different places can range from several tens of meters to several kilometers. Sometimes craters are not completely hidden by lava. Sometimes the craters located under its layer manifest themselves during the subsidence of the young basalts covering them, with the help of their characteristic grinding, which is a repetition of the shape of buried geological structures. Such phenomena are called relict craters.
Seas occupy about 1/3 of the surface area, which is located on the visible side of the Moon, and on the reverse side (see here) their share is only a few percent. The main reason for this is that the center of mass of the Moon is shifted relative to its geometric center and is located in the direction of the side that always faces the Earth. There were times when the speed of rotation of the Moon around its axis was greater, but over time it decreased, and the periods of its rotation around the axis and rotation around the Earth became the same. In this case, the asymmetric location of the Moon’s center of mass played a big role. However, the side of the Moon visible from Earth is currently being subjected to the strongest tidal influences (see Tides). This is due to the fact that it was here that molten basalts most often broke through to the surface.
There is a downside to the coin.
This hemisphere of the Moon, invisible from Earth, is called its reverse side. This circumstance is due to the fact that the periods of the Moon’s revolution around the Earth and rotation around its own axis coincide. The reason for this is that one of the hemispheres of the Moon is always turned towards the Earth. This also applies to the – visible side – here.
A fragment of the surface.
The thin but very rocky surface of the moon is dotted with numerous craters and covered with a layer of regolith (see this here). The thickness of the lunar regolith is 4-5 m in the zones of the lunar seas and 10-20 m on the continents. There are various nuances and differences on different parts of the surface, but there is no effect of water or wind. In the upper part of the surface there are atoms and molecules that are part of the solar wind and gases that are formed as a result of exposure to meteoroids and bombardment by cosmic rays. In recent years, a large amount of water ice has been discovered in the territory, which is located in the polar regions, where the temperature never exceeds minus 2200 C. This was due to the fact that the Sun never rises high above the local horizon here. It is estimated at several billion tons.
General information about the origin.
To date, there are four main hypotheses about the origin of the Moon.
The moon, according to the hypothesis of “rejection”, came out of the Earth’s mantle. According to the hypothesis of “joint origin”, the simultaneous formation of the Moon and Earth from protoplanetary matter as a double planet is possible. It is believed that the Moon appeared elsewhere in the Solar system and was captured by the Earth. And finally, the origin of the Moon is associated with the possibility of combining a ring of protoplanetary matter rotating around the Earth into one whole.
At the moment, the most popular hypothesis is one that combines some of the ideas from the assumptions already considered. It says that at the beginning of the Earth’s existence, there was a collision with a cosmic body with a mass no less than that of Mars. At this moment, in the molten body of the planet Earth, basically, there has already been a division into heavy and light fractions. For this reason, all fractions that contain iron and its accompanying elements: gold, platinum and others have sunk into the depths. As a result of the collision, among other things, a huge amount of light fraction matter was released into near-Earth space.