The light side of the Moon
Question: Why does the light side of the Moon have large plains with few impact craters?

Hypothesis
The numerous meteorite impacts launched rock upward toward Earth, removing the Moon's surface layer (the crust), preventing the accumulation of material on the ground and the creation of the characteristic crater. When an object strikes the surface of a larger object, the first effect is to throw upwards a certain quantity of material which, normally attracted by gravity, falls to the ground forming the typical relief around the point of impact. It is possible, perhaps, that the energy of the impact on the Moon was sufficient to throw rocky material beyond the capacity of gravitation, putting it directly into the Earth's gravity; for example, it has been calculated that the impact that formed the Tycho Crater launched the material about 1,500 km away, perhaps, high enough to be captured by Earth. If you look care fully, this is what happens between all the moons in the solar system, which spill material upwards, and their planets, which capture it; perhaps, this is also why so many "lunar meteorites" are found on the Earth's surface. Probably, with a few calculations (beyond my range), even small objects can release large quantities of rock, removed from the Moon's surface.

In addition, observing the full moon, you can notice the plains on the illuminated side, and along the edges of the disc, almost as those of a crown, you can visible the impact craters on the dark side. This also seem to indicate a relationship between direct exposure to Earth's gravity and the lack of craters. On the lighted side, moon rock is abstracted by Earth's gravity, while on the dark side, the opposite happens: the material launched upwards is still attracted by Earth's gravity but doesn't reach Earth because the Moon is in the midway; it's as if the Moon used Earth's gravity to attract its own rock. Perhaps, this mechanism explains the different appearance of the craters on the two sides: on the dark one they appear to be clearer and more recognizable because the amount of material that falls down to form the edges is greater.

The loss of material due to impacts could explain other characteristics of the Moon. Of course, the illuminated side appears to be thinner than the dark side because the impacts have swept away some of the rock. The dark spots are visible only on the light side because they are the Moon's "mantle," which is made up of harder rock and left exposed, while on the dark side it is still buried by the "crust." The "Eastern Sea" is the best example: the impact was violent enough to dig a hole right through to the mantle, and the Moon's physical barrier to Earth's gravity allowed the material to settle and form the enormous, well-defined edges.

The chemical composition of the two sides also appears different because on the dark side, on top of the original material, the remains of all the asteroids that arrived who knows when and from who knows where have been deposited, while on the light side the materials were captured from Earth. In this regard, it should also be highlighted that the hypothesis that the Earth and the Moon are chemically the same was arising mostly from analyzing the rock samples brought back by the Apollo missions; however, it must be taken into account that these rocks are superficial and could be chemically altered by the impacts of asteroids or be their residues or dates back to periods after the birth of the Earth-Moon binary system.

Another question: The birth of the Moon
Is it possible that the Earth and the Moon are two independent objects and are geologically similar because they were born in the same part of the primordial accrestion disk, similar to the asteroid Cruithne which followed the Earth and only then merge?

Adaptation of Thomas See's " Capture theory "
(The Moon formed at a point in the disk far from the Earth), we can hypothesis that the Earth and the Moon were born in similar orbits and also that the Earth, already larger at its origin, was in front of the Moon along its trajectory in space; this allowed it to absorb more material, becoming larger but also denser, because it has greater gravity than the compact Earth. But as the mass grown, the speed of the orbit decreased and this gave the Moon time to reach Earth, until it get too closer and endlessly it remained trapped in Earth's orbit.

This hypothesis could also partly explain why the Moon has a shortage of nickel, potassium, water, and iron. Iron was probably already present in greater quantities on the Earth's Earth, and this generated a more intense electromagnetic field than the lunar one, which attracted ever more iron. Nickel, potassium, and water are rare on the Moon because while it reached Earth, it found itself in a “shadows cone” created by the Earth along its orbital trajectory or, they could have been washed away by radiation and solar wind.

The idea of the two bodies' slow approach could also explain other aspects. The Moon does not orbit along Earth's equatorial plane, as would be expected based on the theory of the accretion disk formed by post-impact debris. It followed Earth in a close orbit, but not exactly in the same plane, and thus remained in an offset position. For the same reason, Earth's axis tilted: as the Moon slowly approached, its offset position affected only Earth's northern hemisphere. Finally, the Moon is so big, about 25% the size of Earth. It was born in the original cloud, at a similar time as Earth, and has had much more time to absorb material and grow than it had after the impact.

Furthermore, there is perhaps another point that can call into doubt the impact theory. In 1878, George Darwin, son of the famous Charles, proposed the theory of fission: in the beginning there was a single object which then split into two, the Earth and the Moon. His idea proved to be wrong but, in an attempt to prove its correctness, he calculated the trajectory and distance between the two bodies both in the future and back into the past; his calculations demonstrated that the Earth and the Moon could not be a single object because it found that the minimum distance reached was not zero but 8,000 km.

That said, if Darwin's calculations were correct, we can deduce that if they did not have a common point of origin, there was no contact between the two objects, no impact; unless we want to consider "the impact" not as the physical contact between the two objects but as the "explosion" of Theia which occurred about 8,000 km from the surface, similar to the Tunguska meteorite. Or, it could be assumed that at 8,000 km from the Earth's surface the debris created the core of the future Moon which from that point began to orbit as a new independent object, and then slowly moved away (currently the distance from which the Moon began to moving away has been calculated at 24,000 km).

Perhaps, always following Darwin's idea and calculations, we could find a clue to the development of the Earth-Moon system. It has been estimated that Theia was the size of Mars and the Earth slightly larger; when two objects of similar size collide, even if not head-on and at low speed, the impact certainly has consequences on the orbit of the surviving object. By calculating the Earth's orbit in the past, it is perhaps possible to find the period in which there was certainly a change in orbit, perhaps due to the capture of the Moon or the action of Jupiter or the impact with Theia, of what at a certain point transformed into a “binary system”. First there were two objects with different masses and orbits; even before the impact their granities began to interact, but only after they merge, creating a binary system with a different mass, with a larger central object and a new orbit.