The moon, commonly known as the moon, also known as the moon, was also called Taiyin, Xuantu, Chanjuan, and Wangshu in ancient China. It is the only natural satellite of the earth and the fifth largest satellite in the solar system.
The diameter of the moon is slightly larger than a quarter of the earth, and the mass is about 1/81 of the earth. Compared with the planets it orbits, it is the largest satellite in volume and mass, and is also the second densest in the solar system. The highest satellite, second only to Io.
The Chinese word "moon" is a hieroglyph, and in oracle bone inscriptions the moon looks like a crescent moon. When Xu Shen of the Eastern Han Dynasty analyzed the shape of the moon in his book "Shuowen Jiezi", he said: "Moon" means "que". After observation, people found that the full moon spends less time and the crescent moon (quarter moon or eyebrow moon, etc.) spends more time, so they created this pictogram based on the appearance of the eyebrow moon. Extended information
Features:
The Moon is the second densest satellite in the solar system, second only to Io. However, the core of the moon is not large, with a radius of about 350 kilometers or less, which only accounts for about 20% of the size of the moon. In comparison, the proportion of other earth-type celestial bodies is about 50%.
Its composition is not entirely clear, but it may be composed of metallic iron with small amounts of sulfur and nickel. Analysis of the moon's rotation over time shows that the moon's core is still at least partially molten.
The moon is a synchronous rotating satellite of the earth. Its rotation period around its axis is the same as its revolution period around the earth, which makes it almost always face the earth with the same side.
It was rotating at a faster speed before, but later due to the tidal friction caused by the Earth, its rotation speed slowed down until it finally continued to face the Earth with the same side, that is, tidally locked.
People call the side of the moon facing the Earth the front side, and the opposite side is called the back side. The back side is also often called the "dark side", but in fact it will be illuminated just like the front side. . When the moon is in its new phase, we see that the front side of the moon is dark and the back side is illuminated by the sun.
Baidu Encyclopedia – Moon