Why can t you see the far side of the moon and why you can t see the far side of the moon

There is no distinction between front and back on a spherical surface; We can only see one fixed side of the moon because it has to do with the rotation of the earth and the moon.

To understand this phenomenon, you can do an experiment. Draw a circle and mark the east-west-north-south direction. You stand in the center of the circle (representing the earth), find a friend, stand on the circle, have his face facing forward (i.e. without twisting his neck), move counterclockwise along the circle, and ask him to keep his face facing the center of the circle as he moves along the circle, which is you.

Then such a process basically simulates the rotation of the moon and the earth.

Obviously, in such a process, your friend is always facing you in the face. Here's an explanation of why, in such a process, the revolution period is equal to the rotation period.

Your friend starts from your due north, circles you, and when he appears due north again, he completes a revolution. (Similar to the time it takes for the Moon to revolve around the Earth.) )

Let's take a look at what his rotation time is. We might as well set your friend's position when due north of you and face due south as the initial pose. Then we can see that when your friend moves counterclockwise to your due west position, his rotation posture rotates 90 degrees counterclockwise.

If your friend is not in the process"Rotation"then when he is in this position, he is not facing you, but still facing due south. In the actual experiment, your friend is facing due east in this position, so he rotates 90 degrees counterclockwise around himself relative to his initial position.

Similarly, when he walks due south of you, he autobiography 180 degrees relative to his initial posture. When he walks due east of you, he is autobiography 270 degrees relative to his initial posture. When he walks to your due north again, he is autobiographed 360 degrees relative to his initial posture.

That is, he completes a rotation cycle.

Because the completion of a revolution process is just the completion of a rotation process, so from the perspective of time, this rotation period is equal to the revolution period. Because throughout the process, your friend always faces you with his body face, that is, the moon always faces the earth with one side.

The rotation period of the moon is the same as that of the revolution.

Can't see itThe far side of the MoonBecause the rotation and revolution of the Moon are the same, it only faces the Earth, and people will never be able to see the far side of the Moon directly from the Earth.

Under this effect, human beings on the earth basically only see the "front" of the moon forever, and can only see the moon's libra effect (the moon's orbit is elliptical, and the moon's rotation speed is different at different points in the orbit.

It also has a certain inclination relative to the Earth's orbital plane) to see a small part of the "back" of the Moon (the cumulative limit is 18%). But in general, humans cannot see the far side of the moon.

Distribution on the far side of the Moon

The front of the moon has a flat terrain and a lunar sea.

Majority; The color of the back side is brighter, the moon land is the majority, the density of impact craters is also higher than that of the front, and the terrain is more rugged. Among them, the Moon Sea refers to a large area of dark spots on the moon, which actually has no drop of water, and is a wide plain.

The reflection of sunlight in these areas.

It is weaker, so it looks a little darker than the surrounding area. Early astronomers thought that such an area resembled the Earth's oceans, so it was called the Moon Sea, which is still used today. There are a total of 22 lunar seas on the Moon, 19 of which are distributed on the front side, which occupies about the surface area of the Moon.

of 17%, while the far side of the moon is only 3 months of the sea.

The above content reference: Popular Science China - How did Chang'e-4 "see" the far side of the moon?

The reason why you can't see the far side of the moon is because the moon always faces the earth in one place, and because the moon's autobiographical and orbital period are the same. (Day).

The Moon rotates while revolving around the Earth, and the period day is exactly a sidereal month, so we can't see the far side of the Moon. This phenomenon is called "synchronous rotation", or "tide locking", and is almost a universal law in the world of solar system satellites.

It is thought to be the result of the long-term tidal action of satellites on planets. The balance movement is a wonderful phenomenon that allows us to see 59% of the surface of the moon.

There are mainly the following reasons:

In different parts of the elliptical orbit, the rotation speed does not match the angular rotation velocity.

The intersection of the White Lift Road and the equator. The Moon moves half a degree per hour relative to the background starry sky, i.e. it is similar to the apparent diameter of the Moon's surface. Unlike other satellites, the Moon's orbital plane is closer to the ecliptic plane than near the Earth's equatorial plane.

The time it takes for the Moon to orbit the Earth (one sidereal month) is called a sidereal month, relative to the background starry sky; Whereas the time it takes for a new moon to take for the next new moon (or between two phases of the same moon) is called a synodic month. The synodic moon is longer than the sidereal moon because the Earth itself travels some distance in its orbit around the Sun during its orbit.

is due to the phenomenon of tidal locking.

Both the Earth and the Moon have a gravitational pull, but the Earth's gravitational pull is much stronger than that of the Moon. The ebb and flow of the earth is actually related to the gravitational attraction of the moon, because the orbit of the moon around the earth is elliptical, so there is a perigee (closest to the surface) and apogee, and it is the gravitational force of the moon that causes the tidal phenomenon of the earth.

The direction of the moon's revolution around the earth is opposite to the direction of rotation of the earth itself, so the direction of the moon's tidal motion is opposite to the direction of the rotation of the earth's submarine rocks, just like a basin of water splashed on the ball rolling towards itself, which will cause friction to the earth's rotation, and over time, the earth's rotation speed will slow down.

Billions of years ago, the Earth's autobiography was 8 hours per week, but now it is close to 24 hours. This is the tidal lock of the Moon to the Earth, and the gravitational pull of the Earth is much greater than that of the Moon, so this force will be stronger.

The gravitational pull of the earth will cause the interior of the moon to form a pulling force, turning into a pie or an oval, and when the moon rotates, because the shape is not perfectly circular, it will form a rotation due to the gravitational pull of the earth.

In order to make itself more in line with the gravitational pull of the earth, the moon will always make its closest surface to the earth always face the earth, so that the moon's rotation time is the same as its revolution, so the moon has only one side facing the earth.

Why is there no "face" on the far side of the Moon?

In 1959, the Soviet spacecraft Luna-3 showed the world images of the far side of the moon for the first time. At that time, astronomers wondered about the high ground on the far side of the moon. No one can explain why the far side of the Moon is so different from the side facing the Earth.

The far side of the moon is covered with craters. Compared to the Earth-facing side, there are no dark spots on the far side of the moon (these dark spots are formed by large areas of basalt). It is precisely because of these dark spots that the "human face" on the surface of the moon is created.

Astrophysicists at Penn State believe they've solved the puzzle. The absence of dark spots on the far side of the Moon proves the presence of a thick layer of deposits of aluminum and calcium on the far side of the Moon.

One theory suggests that in the early days of the Earth's formation, a planet the size of Mars hit the Earth. This time the impactor was ejected into space and eventually formed the Moon. The tidal action between the Earth and the Moon is such that it is always the same side of the Moon facing the blazing Earth.

As a result, the Earth-facing side of the Moon always remains hot, while the far side cools down. This creates a thick crust on the far side of the Moon.

These astrophysicists at Penn State also believe that it is this hard crust that prevents the basalt magma from flowing out of the surface. When meteors hit the Moon, they are able to break through the surface of the side facing the Earth, causing magma to flow out, which forms the dark spots that make up the "face".

But researchers at the Massachusetts Institute of Technology have drawn new conclusions from new information provided by NASA's "Holy Grail" program. They believe that the "face" on the moon may have been caused by magma inside the moon, rather than by an asteroid impact. However, these researchers are not sure how these magmas are produced.

1. Because the moon is different from the satellites of other planets, the orbit is not along the equatorial plane of the earth but the ecliptic plane, and the angle is about 5 degrees, which can refer to the orbital characteristics of the earth's revolution.

2. The earth revolves for one year, of which the North Pole and the South Pole have a polar day and a polar night for half a year, and there are different degrees of polar day and night traces in the polar circle according to latitude.

3. During the cycle of the Moon, the North Pole and the South Pole cannot see the Moon for half a month.

4. Because the moon is synchronous rotation, the earth has always been able to see only one side of the moon is bright, if you consider the double star orbit, lunar precession, and earth orbit, the time when you can't see the moon is different every month, and the specific area is more complicated.