The moon is also called "the moon". Before the invention of the telescope, ancient people could only look up at the bright moon on a clear night. Seeing the bright and dark colors on the moon's surface and its strange shape, people made up beautiful myths such as Chang'e flying to the moon, Wu Gang cutting osmanthus, and Yu Ming pounding medicine. The ancient Greeks regarded the moon as the beautiful hunting goddess Artemis, and used the silver bow that the goddess never left when hunting as the astronomical symbol of the moon.
The moon basically has no water, so there is no weathering, oxidation, and water corrosion processes on the earth, and there is no sound transmission. There is a silent world everywhere. The moon itself does not emit light, the sky is always dark, and the sun and stars can appear at the same time.
There is almost no atmosphere on the moon, so the temperature difference between day and night on the moon is large. During the day, in places where the sun shines vertically, the temperature is as high as 127°C; at night, the temperature can be as low as -183°C. Because there is no atmospheric barrier, the intensity of sunlight on the moon is about 1/3 stronger than that on the earth; the intensity of ultraviolet rays is also much stronger than that on the earth's surface. Because the moon has a small atmosphere, you will see many strange phenomena on the moon. For example, the sky on the moon is dark and black, and the sunlight is straight. The places where the sunlight shines are very bright; the places where the sunlight does not shine are very dark. That's why we see the moon's surface as bright and dark. Stars no longer appear to twinkle on the moon because there is no air to scatter light.
The lunar surface is full of exposed rocks and silhouettes of craters. The entire moon surface is covered with a layer of gravel and floating soil. The lunar surface as seen from Earth has bright areas and dark gray parts. It turns out that the bright parts are the mountains and highlands on the moon's surface, and the dark gray parts are the plains on the moon's surface.
The moon is smaller than the earth, with a diameter of 3476 kilometers, which is approximately 3/11 of the diameter of the earth. The moon's surface area is about 1/14 of the earth's surface area, slightly smaller than the area of ??Asia; its volume is 1/49 of the earth's. In other words, 49 moons can fit inside the earth. The mass of the moon is 1/81 of the earth; the average density of matter is 3.34 grams per cubic centimeter, which is only equivalent to 3/5 of the earth's density. The gravity on the moon is only 1/6 of the earth. In other words, something weighing 6 kilograms will only weigh 1 kilogram on the moon. When a person walks on the moon, his body seems very relaxed, and he can jump up with a little effort. Astronauts think that walking on the moon, half jumping and half running, seems more enjoyable than walking on the earth.
The moon is the closest celestial body to the earth. It is the only natural satellite orbiting the earth. Its average distance from the earth is about 384,400 kilometers. The Moon's orbit around the Earth is a circular orbit, with an average distance of 363,300 kilometers from its perigee (when it is closest to the Earth) and an average distance of 405,500 kilometers from its apogee (when it is furthest from the Earth), a difference of 42,200 kilometers.
Like the Earth, the Moon is an oblate sphere with slightly flattened poles and a slightly bulged equator. Its average polar radius is 500 meters shorter than its equatorial radius, and the north and south poles are also asymmetrical, with the north pole rising and the south pole sinking about 400 meters.
As the moon moves around the earth, it also moves around the sun with the earth. This means that after the moon moves around the earth once, the space position it returns to is no longer the original starting point. It can be seen that the moon also participates in the movement of multiple systems during its movement. The movement of the moon is the same as that of other celestial bodies. The moon is also in eternal motion. In addition to rising in the east and setting in the west, the moon also moves an average of more than 13° from west to east relative to the stars every day. Therefore, the moon rises every day about 50 minutes later than the previous day. The moon's rising in the east and setting in the west are a reflection of the earth's rotation; while its movement from west to east is the result of the moon's revolution around the earth. The moon's revolution around the earth is called a "sidereal month", which lasts on average 27 days, 7 hours, 43 minutes and 11 seconds. As the moon orbits the earth, it itself rotates. The moon's rotation period and revolution period are equal, that is, 1:1. The time it takes for the moon to orbit the earth is the period of its rotation.