What is hidden on the back of the moon?

Question: What is on the back of the moon?

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As we all know, the moon rotates synchronously with the earth. So on earth, people can only observe the same side of the moon, that is, the front side of the moon. So, what is hidden on its back side?

Some people say that the back of the moon is Guanghan Palace, where Chang'e lives; others say that the earth is actually a cosmic prison, and aliens live on the back of the moon and monitor the earth!

Uh... since it's an official account, let's talk about something serious.

The far side of the moon was first publicly shown in October 1959. At that time, the Soviet Union's Luna 3 spacecraft flew over the lunar surface and took a large number of photos with a twin-lens camera in 40 minutes. One of the lenses captured a panoramic view of the entire far side of the moon. After exposure, washing, fixing, and drying, the photos were finally scanned and transmitted back to Earth through the system.

Although the photo was a bit blurry at the time, it was the first time that humans saw the back of the moon. The most prominent feature of this photo is the basalt-filled Mare Moskva in the upper right corner, the dark Tsiolkovsky crater in the lower right corner, and the bright central peak. The back of the moon is more rugged than the front because the volcanic lava covers less area.

However, the biggest feature of the far side of the moon is its thickness. Today, the average thickness of the moon is 50 kilometers, and the lunar crust on the far side is about 15 kilometers thicker than that on the near side.

Scientists believe that this is because about 4.5 billion years ago, the moon was closer to the earth and was locked in a synchronous orbit with the earth. Over the next 200 million years, the moon gradually cooled down and formed a rocky lunar crust. However, the influence of the earth's gravity and heat made the lunar crust facing the earth thinner and formed more slowly than the far side.

It was not until about 3.9 billion years ago that an asteroid hit the moon, making the two sides of the moon look more similar. Then, between 3.9 billion and 3.2 billion years ago, the surface of the moon cooled, but the radioactive decay inside increased, heating it again, and a balance was reached between the thickening and thinning of the lunar crust. At this time, the moon entered a period of volcanic activity. Due to the difference in thickness between the two sides of the lunar crust, more lava flowed into and filled the deep crater basin on the front side of the moon.

Source: WeChat official account of China Science and Technology Press

Author:cspbooks

Original title: What is on the back of the moon?