Briefly talk about the scientific knowledge about the moon.

The moon is commonly known as the moon, also known as the Moon. The moon is the most obvious example of a natural satellite. In the solar system, all planets except Mercury and Venus have natural satellites. The moon is also about 4.6 billion years old and is closely related to the earth. The moon also has layered structures such as shell, mantle and core. The average thickness of the outermost lunar shell is about 60-65 kilometers. Below the lunar crust 1000 km is the lunar mantle, which occupies most of the moon's volume. Below the moon's mantle is the moon's core, whose temperature is about 1000 degrees, which is likely to be in a molten state. The moon is about 3476 kilometers in diameter, which is 3/ 1 1 of the earth. Its volume is only 1/49 of the earth's, and its mass is about 735 billion tons, which is equivalent to 1/8 1 of the earth's mass. The gravity on the surface of the moon is almost equal to 1/6 of the gravity of the earth.

There are dark parts and bright areas on the moon. When early astronomers observed the moon, they thought that the dark area was covered by seawater, so they called it "sea". The more famous ones are the sea of clouds, the wet sea and the sea of tranquility. The bright part is the mountains, where mountains are stacked and criss-crossed, and craters are dotted. Bailey Crater is located near the South Pole, with a diameter of 295 kilometers, which can hold the whole Hainan Island. The deepest mountain is Newton crater, which is 8788 meters deep. Besides craters, there are ordinary mountains on the moon. Mountains and valleys overlap, giving you a unique perspective.

The front of the moon always faces the earth. On the other hand, most of the back of the moon can't be seen from the earth, except the area near the edge of the moon, which can be seen occasionally due to the movement of Libra. In the era without detectors, the back of the moon has always been an unknown world.

A major feature of the back of the moon is that there are almost no dark moon features such as the moon and the sea. When the probe runs to the back of the moon, it will not be able to communicate directly with the earth.

The moon revolves around the earth for about one lunar month, and moves half a degree relative to the background starry sky every hour, 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.

Because the rotation period of the moon is exactly the same as its period of revolution, we can only see that the moon always faces the earth with the same face. From the early days of the moon's formation, the moon was affected by a moment /url], which led to the slow rotation speed. This process is called tidal locking. Therefore, part of the angular momentum of the earth's rotation is converted into the angular momentum of the moon's revolution around the earth. As a result, the moon is far away from the earth at a speed of about 38 mm per year. At the same time, the earth's rotation is getting slower and slower, and the length of a day is getting longer every year 15 microsecond.

The gravity exerted by the moon on the earth is one of the reasons for the tidal phenomenon. The orbit of the moon around the earth is synchronous, and the so-called synchronous rotation is not strict. Because the orbit of the moon is elliptical, when the moon is at perihelion, its rotation speed can't keep up with the revolution speed, so we can see that the eastern part of the moon reaches 98 degrees east longitude. On the contrary, when the moon is at apohelion, its rotation speed is faster than its revolution speed, so we can see that the western part of the moon passes through 98 degrees Darcy. This phenomenon is called Libra movement. Because the orbit of the moon is inclined to the equator of the earth, when the moon moves in the starry sky, the polar regions will shake about 7 degrees, which is called Libra movement. Furthermore, since the distance between the earth and the moon is only 60 times that of radius of the earth, if the observer observes the moon from sunrise to sunset, the observation point will have the displacement of the diameter of the earth, which can be seen in the area with the longitude of 1 degree. This phenomenon is called Libra movement.

Strictly speaking, the earth and the moon revolve around a concentric center, which is 4,700 kilometers away from the center of the earth (2/3 of radius of the earth's). Because the center of homogeneity is below the surface, the movement of the earth around the center of homogeneity seems to be "shaking". Seen from above the North Pole of the Earth, both the Earth and the Moon rotate clockwise. Moreover, the moon is also clockwise around the earth; Even the earth moves clockwise around the sun.

Many people don't understand why the inclination of the moon's orbit and the inclination of the moon from the axis change so much. In fact, the orbital inclination is relative to the central celestial body (the earth), while the axial inclination is relative to the orbital plane of the satellite (the moon) itself. In this definition, customization is very suitable for general situations (such as the orbit of a satellite) and the value is quite fixed, but the moon is not.

The orbit plane of the moon (ecliptic plane) keeps an included angle of 5. 145396 with the ecliptic plane (earth's orbit plane), while the rotation axis of the moon forms an included angle of 1.5424 with the normal of the ecliptic plane. Because the earth is not a perfect sphere, but bulges at the equator, the white road surface keeps precessing (that is, the intersection with the ecliptic rotates clockwise) and completes one week every 6793.5 days (18.5966). During this period, the angle between the white plane and the equatorial plane of the earth (the equatorial plane of the earth inclines to the ecliptic plane at 23.45) will change from 28.60 (i.e. 23.45+5. 15) to18.30 (i.e. 23.45-5. 15). Similarly, the angle between the rotation axis of the moon and the white plane will be between 6.69 (that is, 5. 15+ 1.54) and 3.60 (that is, 5. 15- 1.54). These changes in the lunar orbit will in turn affect the inclination of the earth's rotation axis, making it swing by 0.002 56, which is called nutation.

The two intersections between the ecliptic plane and the ecliptic plane are called the lunar intersection-the ascending intersection (north point) refers to the point where the moon passes to the north of the ecliptic plane; Descending node (South Point) refers to the point where the moon passes south of the ecliptic. When the new moon is just at the intersection of the moon, a solar eclipse will occur; An eclipse occurs when the full moon is just at the intersection of the moons.