The moon, commonly known as the moon, was an ancient moon, which was a satellite orbiting the earth. It is the only natural satellite on Earth and the closest celestial body to the earth (the average distance between it and the earth is 384,400 kilometers). In 1969, Neil Armstrong and Buzz Aldrin became the first human to land on the moon. In September 1969, the American Apollo 11 spacecraft returned to Earth, and the American Apollo lunar landing program ended on Apollo 17. There is also the American movie "Moon" released in 2009.

The moon is the most thoroughly studied celestial body. The second celestial body that humans have visited has been to this day is the moon. The moon is about 4.6 billion years old. The moon has a layered structure like the earth, such as crust, mantle, and core. The average thickness of the outermost lunar crust is about 60-65 kilometers. The depth below the lunar crust to 1,000 kilometers is the lunar mantle, which accounts for most of the moon's volume. Below the lunar mantle is the lunar core, and the temperature of the lunar core is about 1,000 degrees, which is likely to be in a molten state.

The moon's diameter is about 3474.8 kilometers, about 1/4 of the earth, about 1/400 of the sun, and the distance from the moon to the earth is equivalent to 1/400 of the distance from the earth to the sun, so from the earth, the moon is as big as the sun. The volume of the moon is about 1/49 of the earth and its mass is about 735 billion tons, which is almost equivalent to about 1/81 of the earth's mass. The gravity on the surface of the moon is about 1/6 of the earth's gravity. There is a dark surface on the surface of the moon

The dark parts and bright areas, the bright areas are highlands, and the dark areas are low-sinking areas such as plains or basins, which are called the moon land and the moon sea respectively. When early astronomers observed the moon, they thought that dark areas were covered with sea water, so they called them "sea". The famous ones are the sea of ​​clouds, wet seas, quiet seas, etc. The bright parts are mountains, where mountains are stacked and mountains are scattered everywhere, namely the moon pit, which is a circularly raised low-lying shape.

.There are more than 33,000 craters on the moon with a diameter of more than 1 kilometer. The Bailey crater near the Antarctic has a diameter of 295 kilometers, which can fit the entire Hainan Island into it. The deepest mountain is Newton crater, with a depth of 8,788 meters. In addition to the craters, there are also ordinary mountains on the moon. High mountains and deep valleys appear, which has a unique scenery. The moon always faces us on one side (see the explanation for the reason later). This side is used to be the frontal map of our moon.

On the other hand, except that the area near the edge of the moon is visible in the middle due to the movement of the Libra, most of the back of the moon cannot be seen from the earth. In the era without a probe, the back of the moon has always been an unknown world. One of the major features of the back of the moon is that there is almost no darker lunar feature, such as the Moon Sea. When an artificial probe runs to the back of the moon, it will not be able to communicate directly with the earth. The moon orbits the earth for one week in 27.321666, and moves relative to the background starry sky every hour.

Half a degree of motion, that is, the apparent diameter of the moon surface is similar. Unlike other satellites, the moon's orbital plane is closer to the ecliptic plane, rather than near the equatorial plane of the earth. Compared with the background starry sky, the time required for the moon to orbit the earth (the moon orbit) for one week is called a star moon; and the time required for the new moon to the next new moon (or between two identical moon phases) is called a synagogue moon. The synagogue moon is longer than the star moon because the earth itself also advances a distance in the orbit of the sun during the moon operation. Because the moon

The rotation period is exactly the same as its rotation period, so only on earth can you see the moon facing the earth with the same side forever. Since the early stages of the moon formation, the earth has been affected by a torque, causing the rotation speed to slow down. This process is called tidal locking. Therefore, the angular momentum of some earth's rotation changes into the angular momentum of the moon orbiting the earth. As a result, the moon is away from the earth at a speed of about 38 mm per year. At the same time, the rotation of the earth is getting slower and slower, and the length of the day becomes 15 microseconds per year. The moon

The gravity exerted on the earth is one of the causes of tidal phenomena. The moon orbits around the earth are synchronous orbits, and the so-called synchronous rotation is not strictly. Since the moon orbit is elliptical, when the moon is in perigee, its rotation speed cannot keep up with the rotation speed. Therefore, we can see that the area at 98 degrees east longitude in the east longitude in the east. On the contrary, when the moon is in a distant position, the rotation speed is faster than the rotation speed, so we can see that the area at 98 degrees west longitude in the west of the moon. This phenomenon is called through Libra. Looking at the earth from the moon

Strictly speaking, the earth and the moon revolve around the common center of mass, with the common center of mass being 4,700 kilometers away from the center of the earth (that is, 3/4 of the earth's radius). Since the common center of mass is below the surface of the earth, the movement of the earth around the common center of mass seems to be "swaying". From above the south pole of the earth, both the earth and the moon rotate clockwise; and the moon also revolves around the earth clockwise; even the earth revolves around the sun clockwise. The reason for this phenomenon is that the earth, the moon has the same angular momentum relative to the sun, that is, "turns in this direction from the beginning." Many people do not understand why the inclination angle of the moon orbit and the inclination angle of the axis of the moon

The value will change so much. In fact, the orbital inclination is relative to the central celestial body (i.e. the earth), and the rotation axis is inclination relative to the satellite. The moon's orbital plane (white path plane) and the ecliptic plane (earth's orbital plane) maintain an angle of 5.145396°, while the moon's rotation axis is at an angle of 1.5424° with the normal of the ecliptic plane. Because the earth is not perfectly spherical, it is relatively uplifting at the equator, so the white path plane is constantly precipitating (i.e. the intersection with the ecliptic is rotating clockwise), completing a week every 6793.5 days (18.5966). During this period, the white path plane is relative to the earth's equator (earth's equatorial plane at 23.

The angle of 45° inclination to the ecliptic plane will change from 28.60° (i.e. 23.45°+5.15°) to 18.30° (i.e. 23.45°-5.15°). Similarly, the angle between the moon's rotation axis and the white path will also be between 6.69° (i.e. 5.15°+1.54°) and 3.60° (i.e. 5.15°-1.54°). These changes in the moon's orbit will in turn affect the inclination angle of the earth's rotation axis, causing it to swing ±0.00256°, which is called the Zhangdong. The two intersections between the white path and the ecliptic plane are called the lunar intersection - where the ascending intersection point (north point) refers to the moon passing through this point to the north of the ecliptic plane.

; Descending point (south point) refers to the moon passing through this point to the south of the eclipse. When the crescent moon is just at the lunar intersection, a solar eclipse occurs; and when the full moon is just at the lunar intersection, a lunar eclipse occurs. The structure and frontal differences on the back of the moon are relatively large. The moon sea occupies a small area, while the craters are more numerous. The terrain is uneven, and the longest and shortest radius of the moon, both are located on the back. Some places are 4 kilometers longer than the average radius of the moon, and some places are 5 kilometers shorter (such as the Van der Graff depression). No "mass tumor" is found on the back. The lunar crust on the back is thicker than the frontal, with a thickest area of ​​150 kilometers, while the lunar crust on the front is only about 60 kilometers thick. The map of the back of the moon

The moon itself does not glow, only reflects sunlight. The brightness of the moon changes with the changes of the sun, the angular distance between the moon, the earth, and the distance between the moon. The average brightness is 1/465,000 of the sun's brightness, and the amplitude of the brightness changes from 1/630,000 to 1/375,000. The average brightness at the full moon is -12.7, etc. (see). The average illumination of the earth is 0.22 lux, which is equivalent to the illumination of a 100-watt electric lamp at a distance of 21 meters. The moon is not a good reflector, its average albedo is only 7%, and the remaining 93% are absorbed by the moon. The albedo of the moon is lower, about 6%. The albedo of the moon's high ground and the crater is 17%, which looks like the mountain is brighter than the moon. The brightness of the moon changes accordingly, and the brightness at the full moon is more than ten times greater than the upper and lower strings. Since there is no atmosphere on the moon, plus the moon

The thermal capacity and thermal conductivity of surface matter are very low, so the temperature difference between day and night on the moon surface is very large. During the day, the temperature is as high as +127℃ in places where sunlight is vertically illuminated; at night, the temperature can be reduced to -183℃. These values ​​only represent the temperature on the moon surface. Radio observation can be used to measure the temperature in the lunar soil. This measurement shows that the temperature in the deeper soil in the lunar soil rarely changes, which is precisely due to the low thermal conductivity of lunar material. From the propagation of lunar shock waves, it is learned that the moon also has crust, mantle, core and other layered structures. The outermost lunar crust is 60 to 65 kilometers thick. The depth below the lunar crust to 1,000 kilometers is the lunar mantle, accounting for most of the volume of the moon. Below the lunar mantle is the lunar core. The temperature of the lunar core is about 1,000℃, which is likely to be molten. It is speculated that it is probably composed of Fe-Ni-S and eclogite matter.

Basic data

Photos of Apollo moon landing (19 photos) Average orbital radius 384,401 kilometers orbital eccentricity 0.0549 Periginal distance 363,300 kilometers Average distance 405,500 kilometers Average period 27.32 days Average revolution velocity 1.023 kilometers/sec Orbital inclination varies between 28.58° and 18.28° Ascension point 125.08° Periginal angle 318.15° Modwin Chapter 19 average lunar and earth distance 384,400 kilometers Annual regression period 18.61 years Periginal motion period 8.85 years eclipse year 346.6 days Saro period 18 years 10/11 days Average inclination angle between orbit and eclipse 5° The level of the lunar equator and the eclipse

The average inclination angle is 1° Equatorial diameter 3,476.2 kilometers Pole diameter 3,472.0 kilometers Flatness 0.0012 Surface area 3.79×10^7 square kilometers Volume 2.199×10^10 cubic kilometers mass 7.349×10^22 kilograms of average density of water 3.350 times the equatorial gravity acceleration 1.62m/s2 (1/6 of the earth) Escape speed 2.38 kilometers/sec rotation period 27 days 7 hours 43 minutes 11.559 seconds (simultaneous rotation) Rotation speed 16.655 meters/sec (at the equator). The angle of the rotation axis changes between 3.60° and 6.69° and the intersection angle with the ecliptic is 1.5424° Albedo 0.12 Moon in the universe

At full moon, the apparent magnitude is -12.74 Surface temperature (t) -233~123℃ average atmospheric pressure 1.3×10-10 kPa period: name value (unit: day) defines the star moon 27.321661 relative to the background star synodic moon 29.530588 relative to the sun (moon phase) point 27.321582 relative to the vernal equinox perimeter 27.554550 relative to the perigee intersection 27.212220 relative to the ascending intersection lunar moon The diameter of the moon is 1/4 of the earth's average diameter, and the mass is only 1/81 of the earth.

The name Craft crater is Galileo. It is a distinctive feature of the moon surface and almost covers the entire moon surface. The largest crater is Bailey Crater near Antarctica, with a diameter of 295 kilometers, which is a little larger than Hainan Island. The small crater may even be a pit of dozens of centimeters. There are about 33,000 with a diameter of no less than 1,000 meters, accounting for 7%-10% of the surface area of ​​the lunar surface. A Japanese scholar proposed a classification method for craters in 1969, which is divided into the Crave type (ancient craters are generally unrecognizable, and some have mountains around the mountains) Copernicus type (young ones).

Crafts often have "radiation patterns", and the inner walls generally have concentric circles, and the center is generally centered peaks. Archimedes (the ring wall is lower, which may evolve from the Copernicus type) bowl-type and dimples type (small craters, some of which are less than 3 meters in diameter). There are two current theories for the formation of craters: "impact theory" and "volcanic theory". "impact theory" refers to the moon's craters that humans see now because they were hit by other planets. The "volcanic theory" refers to the fact that there were many volcanoes on the moon, and finally the volcano erupted and formed craters. However, what scientists today advocate is the "impact theory".

The dark part of the moon surface seen by humans on the earth with their naked eyes is actually the vast plains on the moon surface. Due to historical reasons, this name that is not worthy of its name remains.

There are 22 lunar seas that have been identified, and some terrains are called "Moon Sea" or "Moon Sea". Most of the recognized 22 are distributed on the front of the moon. There are 3 on the back and 4 on the edge. The area of ​​the moon seas in the front is slightly greater than 50%, and the largest "Storm Ocean" covers an area of ​​about 5 million square kilometers, which is almost the sum of the area of ​​nine Frances. Most of the moon seas are roughly round and oval, and are mostly closed by some mountains around them, but some seas are connected together. In addition to the "sea", there are five "lakes" with similar terrain - Menghu, Death Lake, Xiahu, Qiuhu, and Chunhu, but some lakes are more than

The sea is still large, such as Meng Lake, an area of ​​70,000 square kilometers, which is much larger than the sea of ​​Qi. The part of the moon sea extending to the land is called "wan" and "swamp", and they are all distributed on the front. There are five bays: Luwan, Summer Bay, Central Bay, Hongwan, Meiyue Bay; there are three swamps: Frug, Epidemic Swamp, Mengwan, and In fact, there is no difference between swamps and bays. The terrain of the moon sea is generally low, similar to the basins on the earth. The moon sea is 1-2 kilometers lower than the average level of the moon, and some of the lowest seas are even 6,000 meters lower than the surrounding area. The albedo of the moon surface (a physical quantity that measures the ability to reflect sunlight) is also relatively low, so it looks darker.

The area above the moon's sea is called the Moon Land, which is generally 2-3 kilometers higher than the Moon Sea level. Because of its high reflex, it looks brighter. On the front of the moon, the area of ​​the Moon Land is roughly the same as the Moon Sea, but on the back of the Moon, the area of ​​the Moon is much larger than the Moon Sea. From isotope measurement, it is known that the Moon Land is much older than the Moon Sea and is the oldest topographic feature on the Moon. On the moon, in addition to the many craters with canine teeth, there are also some mountains similar to that on the Earth. The mountains on the moon often borrow the names of the mountain ranges on the earth, such as the Alps, the Caucasus Mountains, etc. The longest mountain range is the Apennines, which stretches 1,000 kilometers, but the height is only three or four kilometers higher than the Moon Sea level. There are also some steep peaks on the mountains, and their altitudes are estimated to be higher in the past

.It is now believed that most peaks are similar to those of the heights of the Earth. In 1994, the Clementine lunar probe in the United States concluded that the highest point of the moon was 8,000 meters. According to the data obtained by "Chang'e-1", the highest peak on the moon was as high as 9,840 meters. There are 6 peaks above 6,000 meters, 20 peaks on the moon surface, 5,000-6,000 meters, 80 for 3,000-6,000 meters, and 200 for 1,000 meters. The mountains on the moon have a common feature: the slopes on both sides are very asymmetric, and the slopes towards the sea are very large, sometimes cliff-shaped, and the other side is quite smooth. In addition to mountains and mountains, there are four cliff-long cliffs on the moon surface that are hundreds of kilometers long. Three of them protrude in the moon sea, and this kind of cliff is also called "moon chasing".

The radiant pattern of the moon is that some of the more "young" craters often have beautiful "radiant patterns", which are a bright band that extends in all directions with the crater as the radiation point. It almost passes through the mountain system, the sea of ​​moon and the crater in a straight direction. The length and brightness of the radiant pattern are different. The most eye-catching is the radiation pattern of the Tycho crater. The longest one is 1,800 kilometers long, which is particularly spectacular at the full moon. Secondly, the two craters of Copernicus and Kepler also have similarities.

When it comes to beautiful radiation patterns. According to statistics, there are 50 craters with radiation patterns. The reason for the formation of radiation patterns has not yet been concluded. In essence, it is closely related to the theory of formation of craters. Many people now prefer meteorite impact theory, believing that on a moon without atmosphere and very little gravity, meteorite impact may cause high-temperature fragments to fly far away. Other scientists believe that the role of volcanoes cannot be ruled out, and eruptions during volcanoes may also form radiation shapes that scatter around.

There are many famous rift valleys on the earth, such as the Great Rift Valley in East Africa. There is also this structure on the moon surface---the seemingly winding black cracks are the Moon Valley. Some of them stretch hundreds to thousands of kilometers and range from thousands to tens of kilometers. The wider rifts mostly appear in flatter areas on the moon land, while those narrower and smaller rifts (sometimes called Moon Creek) are everywhere. The most famous rift valley is the Alps in the southeast of the Plato Crater, which connects the rainy sea and the cold sea. It cuts the Alps on the moon in half, which is very spectacular. From the photos taken from space, it is estimated that it is 130 kilometers long and 10-12 kilometers wide.

The surface of the moon is covered by huge basal lava (volcanic lava) layers. Early astronomers believed that the dark areas on the moon's surface were vast oceans, so they called it "mare". This word means "sea" in Latin. Of course, this is wrong. These dark areas are actually plains composed of basal lava. In addition to basal lava structure, the dark areas of the moon also have other volcanic characteristics. The most prominent ones are winding lunar grooves, black sediments, volcanic garden tops and volcanic cones. However, these characteristics are not significant, just a small part of the volcanic traces on the surface of the moon. Compared with the volcano on the earth, the lunar volcanoes are old. Most lunar volcanoes are between 3 and 4 billion years old.

The youngest lunar volcano is 3.5 billion years old; the youngest lunar volcano is also 100 million years old. In the geological age, the Earth's volcano is in youth, generally less than 100,000 years old. The oldest rock formation on the earth is only 390 million years old, and the oldest basalt is only 2 million years old. The young Earth's volcano is still very active, but the moon has no signs of new volcanoes and geological activity. Therefore, astronomers call the moon a "extinguished" planet. Most of the Earth's volcanoes are distributed in chain shape. For example, the Andes Mountains, the volcano chain outlines the edge of a lithosphere plate. The mountain chains on the island of Hawaii show the hot zone of plate activity. There are no signs of plate tectonics on the moon. Typical moon fire

Most mountains appear at the bottom of huge and ancient impact craters. Therefore, most of the dark areas of the moon have a circular appearance. The edges of the impact basin often surround mountains and surround dark areas. The dark areas of the moon mainly appear on the far side of the moon, covering almost 1/3 of the area of ​​this side. On the far side, the area of ​​the dark areas only accounts for 2%. However, the terrain on the far side is relatively higher and the crust is thicker. It can be seen that the main factors controlling the effect of lunar volcanoes are the surface height and crust thickness. The gravity of the moon's center is only 1/6 of that of the earth, which means that the flow resistance of the lunar volcanic lava is smaller than that of the earth and the lava travels smoother. This can explain why the surfaces of the dark areas of the moon are mostly flat and smooth. At the same time, smooth

The lava flow can easily spread, thus forming huge basalt plains. In addition, the gravity of the earth is low, so that the erupted volcanic ash debris can fall further. Therefore, the eruption of the lunar volcano only forms a wide and flat lava plain, rather than a volcanic cone similar to the earth's form. This is also one of the reasons why no large volcanoes were found on the moon. There is no dissolved water on the moon. The dark areas of the moon are completely dry. Water is the most common gas in the earth's lava and is one of the important factors that arouse strong eruption of the earth's volcano. Therefore, scientists believe that the lack of water also has a huge impact on the activities of the moon's volcano. Specifically, without water, the eruption of the moon's volcano will not be so strong, and the lava may just flow to the ground calmly and smoothly.

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