Flying around the earth and the moon! First of all, I'm a little Bai, so I asked the question, why does an aircraft (such as Tiangong, chang'e-3, etc.) have to fly around the earth for a long time before it can run to the moon when it is launched? When it is approaching the moon, it will fly around the moon for a long time before it can land, instead of flying vertically to the moon! Please tell me, and don't copy other people's answers, I've seen the answers given by others, but they are not specific enough! Rockets can't directly raise the aircraft to a certain speed, can they fly around the earth to a certain speed? Why do many people say that they save fuel? Why do they save fuel?

Flying around the earth and the moon! First of all, I'm a little Bai, so I asked the question, why does an aircraft (such as Tiangong, chang'e-3, etc.) have to fly around the earth for a long time before it can run to the moon when it is launched? When it is approaching the moon, it will fly around the moon for a long time before it can land, instead of flying vertically to the moon! Please tell me, and don't copy other people's answers, I've seen the answers given by others, but they are not specific enough! Rockets can't directly raise the aircraft to a certain speed, can they fly around the earth to a certain speed? Why do many people say that they save fuel? Why do they save fuel?

As a former physics student, I understand it as follows:
First of all, we need to make clear the "first space speed". In short, as long as the spacecraft reaches this first space speed, it can fly around the earth orbit without using any external force. Above this speed, the spacecraft will gradually fly out of the earth orbit
Baidu said that the first speed of the earth's universe is 7.9km/s, and the speed of the spacecraft flying to the moon is 10.7km/s. It may not be convenient to accelerate directly to this speed, so scientists sent the spacecraft to the earth orbit to accelerate to the first speed of the universe. The spacecraft can rotate around the earth without power. On this basis, slightly accelerate to a higher speed than the first speed of the universe, The spaceship will fly away from the earth and approach the moon
When it approaches the moon and enters the lunar orbit, it will slow down to less than the first cosmic speed of the moon. Then it will be "captured" by the gravity of the moon and fall to the surface of the moon. In the process of falling, it will use some deceleration and buffer devices to make the fall lighter, that is, it will land
I hope it will help you