The full moon is like a wheel, a disk and a mirror, so it is called the moon.

Because the full moon is like a wheel and the plate is like a mirror, it is called golden wheel, jade wheel, silver plate, jade plate, gold mirror and jade mirror.

The moon is commonly known as the moon, also known as the Moon. The earth's only natural satellite is about 4.6 billion years old. The average distance between the moon and the earth is 380,000 kilometers, the head of the moon is 1/49 of the earth, the diameter of the moon is about 1/4 of the earth, the mass is about1/8 of the earth, and the gravity on the moon is only 1/6 of the earth.

The moon is a dead world. Without air, of course, there will be no wind and no dust. Without water, there would be no water vapor, not to mention weather phenomena such as rain, snow, hail, clouds, fog, frost and dew. Therefore, apart from being hit by meteorites, the footprints left by astronauts on the moon are only threatened by the solar wind and cosmic particle flow.

However, it will take tens of millions of years for these particle streams to wear away the moon dust of1mm. Therefore, human footprints have hardly been destroyed since 1969 left on the moon.

The rotation of the moon

The moon revolves around the earth and rotates at the same time, with a period of 27.438+066 days, which happens to be a sidereal moon, so we can't see the back of the moon. This phenomenon, which we call "synchronous rotation" or "tidal locking", is almost a universal law in the satellite world of the solar system.

It is generally believed that it is the result of long-term tidal action of satellites on the planet. The libration is a wonderful phenomenon, which enables us to see 59% of the moon. The main reasons are as follows: in different parts of elliptical orbit, the rotation speed does not match the revolution angular speed. The intersection of the white road and the equator.

The appearance of the moon moves half a degree per hour for the background starry sky, which is similar to the apparent diameter of the moon. Unlike other satellites, the orbital plane of the moon is closer to the ecliptic plane than the equatorial plane of the earth.

Relative to the background starry sky, the time required for the moon to go around the earth (the moon makes one revolution) is called sidereal month; The time between the new moon and the next one (or the time between two identical moon phases) is called the new moon. The reason why Wang Shuo's moon is longer than that of the star moon is that during the earth's operation on the moon, it moved forward a certain distance in its orbit around the sun.

Baidu Encyclopedia-Moon