Why does the Moon always face the same face to the Earth and cannot be seen from the Earth

First, in terms of the mass distribution of the Moon, the Moon is not an absolute sphere, and second, the Earth's oceans have a tidal effect on the Moon (rocks, land, etc. also have tidal forces, but they are weaker than the oceans).

At first, the revolution of the moon and the autobiography are not synchronized, so that when the moon revolves around the earth, the tidal force has an effect on the moon, and this effect has two effects on the moon, the first is the magnification relationship between the revolution and the autobiography, that is, when the moon is relative to the earth (with the earth as a reference frame) the autobiographical period is an integer multiple of the revolution period, then the tidal force is a very regular change effect for the moon, then the rotation of the moon will be stable, and when the rotation and revolution are not multiples, the effect of tidal force on the moon is irregular, and the effect of this irregularity is to make the rotation of the moon tend to be a multiple of the revolution, and finally the moon's autobiography will be stable on a multiple of his revolution period, as for how many times depends on his own rotation period, if the rotation is a multiple of the revolution, then when the moon's rotation stabilizes, he must be 3 times the rotation period, if it is a multiple, it is finally synchronized with the revolution.

Since the rotation and rotation cycles are the same, the moon we see is naturally only the same side, so we can't see the back of the moon. I just mentioned that tidal forces have two effects on the moon, and now there is a second effect that is not said, that is, the moon is moving away from the earth, which is also due to tidal forces. So we know that considering the Earth-Moon system, the lunar principle of the Earth must have become more mechanical energy (although the kinetic energy is smaller, but the gravitational potential energy has increased greater), so how does the Moon obtain these energies and move away from the Earth?

Then this involves the effect of tidal forces on the earth, just now only consider the two effects of tides on the moon, then for the earth-moon system the earth has no kinetic energy, gravitational potential energy has just been considered, so what other energy is involved? That is the earth's rotational energy **kinetic energy), the moon's principle of the earth at the same time, our earth's self-transformation is slow, that is to say, a long time ago the earth's day was shorter than now, and in the long future the earth's day will be longer than now. That's what we're doing right now.

Because of the phenomenon of tidal locking, only one side of the Moon faces the Earth. At the beginning of the formation of the Moon, the Moon's rotation speed was very fast, which caused them to rotate several times around the Earth in one circle. However, due to the inconsistency of rotation and revolution speed, the moon is constantly deforming in the process of rotation, which will consume the kinetic energy of the moon, causing the moon's rotation speed to become slower and slower, until the moon's rotation speed is consistent with the revolution speed, and then only one side faces the earth.

When the Moon is tidally locked, the Moon faces the Earth in the same way, standing on the Earth, and the far side of the Moon is no longer visible. In fact, not only does the Earth have a tidal force on the Moon, but the Moon can also tidally lock the Earth, and most of the tidal changes we see in the Earth's oceans are caused by the Moon.

Because the Earth is massive and the Moon is small, we know that the gravitational pull is related to the mass of the celestial body, so the gravitational pull of the Moon is smaller, and it takes longer to tidally lock the Earth.

At present, the moon has slowed down the earth's rotation speed, at the beginning of the formation of the earth took 8 hours to rotate the earth, a while ago scientists found that the age of dinosaurs was only one hour a day, and today the earth's rotation speed is 24 hours. If the Earth's history is long enough, it may take a month for the Earth to make one rotation in the future, which means that the Earth is tidally locked by the Moon.

There is only one side of the Moon that people see on Earth because the rotation of the Moon is the same as the period of revolution, that is, every revolution of the Moon is exactly one revolution. This means that one side of the moon is always facing the Earth and the other is always facing away from the Earth, a phenomenon known as "tidal locking".

Tidal locking is a phenomenon that is widely present in celestial bodies, such as the Moon on Earth and the Sun on Mercury. The principle is based on the interaction and gravitational pull between celestial bodies, and when the gravitational pull of one celestial body is large enough, it is able to create gravitational tides that synchronize the rotation period and orbital period of another celestial body so that one side of them always faces each other, thus achieving tidal locking. In the case of the Moon, the Earth exerts a gravitational pull on the Moon so that the Moon is tidally locked, always facing the Earth in the same way.

Although we can always only see one side of the moon, we can see the real scene of the other side of the moon through the observation of spacecraft and **. Since 1959, when the Soviet Union's Luna-3 began taking images of the far side of the moon, space agencies and scientists around the world have been exploring more of the moon's mysteries. For example, China's Chang'e-4 mission successfully landed on the far side of the moon in 2019, the first time in human history, giving us a deeper understanding of the nature and structure of the moon.

In summary, only one side of the Moon is exposed to the human eye because of their gravitational interaction with the Earth, especially due to the gravitational tides that align the Moon's rotation and revolution periods. Although we cannot directly observe the far side of the moon, we already have a more complete picture of the moon and a deeper understanding through modern space technology.