How did humans know that the moon was weightless?

The Moon is not "weightless", but the gravity on the surface of the Moon will be less than the gravity on the ground.

As for the process of understanding the gravitational strength of each celestial body, it starts with the law of gravitation. The magnitude of the gravitational force between two objects is directly proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between the centers of gravity of the two objects. When examining a person on the surface of a planet, the distance between man and the planet is the radius of the planet, and since the mass of a person is much smaller than the mass of the planet, the mass of a person can be ignored when calculating gravity.

The magnitude of the gravitational force between the Earth and the Moon can be found by the period of the Moon's orbit around the Earth and the distance between the Earth and the Moon. Knowing the magnitude of gravity, we know the value of the product of the mass of the Earth and the Moon. Subtracting the Earth's mass from this value gives us the mass of the Moon, which is only 1/81 of the Earth's mass.

The size of the Moon is easy to measure, and with the general trigonometric method, astronomy enthusiasts can do it. Knowing the mass of the Moon and its radius, the gravitational strength on its surface is easy to calculate – about one-sixth of the Earth's surface.

This knowledge will be learned in middle school physics, and if you are interested, you can actually check it, which is very meaningful.

There are "one big step for the world" in Amsterdam and physicists for precise calculations, and you can also study hard to disprove their views. Who says scientists are all right?

Dear landlord:

It can be conceived in two ways that this problem should be "solved"! 1. Modify the Moon and increase its density to make it heavier enough to produce its own gravitational pull that rivals that of the Earth; 2. Transform human beings, so that the "new man" can still live freely and conveniently in microgravity, and even do not need to breathe oxygen! Obviously, the two retrofit options are rationally achievable, but at the cost.

By the way, the landlord is at any cost, hahahaha.

Good luck with your progress.

Looking forward to you, thank you.

The results of astronomers' calculations and tests.

is through the mass of the planet.

In life, overweight and weightlessness are very common, for example, when people are in the elevator, when the elevator accelerates up, they feel that the pressure on the soles of the feet of the elevator increases, which is the phenomenon of overweight.

In order to reduce the pressure on the bridge, the bridge generally causes a convex shape, so that the car has a downward acceleration when crossing the bridge and the pressure on the bridge is reduced, when the car passes through the sunken road surface, due to the vertical upward acceleration and the phenomenon of overweight, often make the car tire burst due to the high pressure.

Due to gravity, on the ground, the balls made with modern technology are not absolutely spherical, which is one of the important reasons for the wear of the bearings, if in the spacecraft can be made of absolutely spherical balls, and the astronaut in the spacecraft due to complete weightlessness, so his diet, life methods must be very different from the ground. Overweight and weightlessness are two opposite concepts, so I'll explain them to you together.

There is an object and we assume the mass m. Now, this object is moving vertically upwards (i.e., in the direction of leaving the Earth) with acceleration a. Obviously, because of this motion, the pressure n on the horizontal support surface (or the tension t on the vertical overhang) is greater than the weight of the object itself, which should be equal to m(g+a).

This phenomenon is called overweight. We often say that the object is overweight.

Similarly, now, if the object moves vertically downward (i.e., towards the Earth) with acceleration a, the pressure n (or tension t) above will be less than the weight of the object itself, which should be equal to m(g-a). This phenomenon is called weightlessness. We often say that the object is weightless.

If a = g, then the object is in fact in free fall, the pressure n (or tension t) is zero, and we say that the object is completely weightless

For example, an object in a satellite that moves in a uniform circular motion around the Earth has zero pressure on the satellite's floor because its vertical downward acceleration a is the gravitational acceleration g at the position of the satellite.

Of course, in daily life, we can also experience overweight and weightlessness. For example, in an elevator, we can go through the process of being overweight and weightless. When the elevator starts to ascend, we are overweight at this point as we have an upward acceleration along with the elevator.

On the contrary, when the elevator starts to descend, we are weightless at this point as we have a downward acceleration along with the elevator. If the elevator breaks down, we will fall down with the elevator. We must be completely weightless at this point.

However, of course, we would rather not have such an experience.

On Earth, because of the attraction of the Earth (that is, gravity), it feels like we always have weight, but when it comes to the Moon, it is the attraction of the Moon, because the gravitational force on the Moon is not as great as on the Earth, we feel as if we are weightless, everything is the same on the Moon, in fact, the Moon also has weight, but it is relatively small, and it feels weightless, understand?

The Moon is subject to the gravitational pull of the Earth, and the gravitational force it receives is used to provide the centripetal force of the Moon moving in a uniform circular motion around the Earth. This gravitational force may also be called gravity. The objects on the moon are also subject to the gravity of the earth, but this gravity is also used to do the centripetal force of circular motion, so the gravity of the objects on the moon is completely weightless for the earth, but the objects on the surface of the moon are also subject to the gravitational force of the moon, and this gravitational force can be measured with a spring scale.

The objects in the space shuttle are completely weightless, but the same reasoning as above is not that these objects are not subject to gravity, but that the gravity of these objects is all used to provide the centripetal force for their circular motion around the Earth. So the pulling force on the suspended spring scale is zero.

The essence of gravity is still gravitational force, and the moon should be said to be subject to the gravitational pull of the earth, and it is not interesting to say gravity.

Weightlessness of celestial bodies? Do you mean the weightlessness of astronauts after flying to the moon? That is, on the moon, the gravitational pull of the moon on people is not as great as when it is on earth.

The so-called weightlessness means that the gravity is zero, that is, zero gravity.

The so-called gravitational force is the gravitational pull of celestial bodies on objects.

The magnitude of the gravitational force is directly proportional to the mass and inversely proportional to the square of the distance.

In the case of a celestial body with a certain mass, the farther away the object is from it, the less gravitational pull it will experience, that is, the smaller the gravitational force.

At a distance of sufficient distance, its gravitational pull is negligible. But there is more than one celestial body in the universe, and many celestial bodies are introduced.

The force forms a gravitational field. Therefore, space will not be a weightless environment.

Of course, in terms of local areas, such as in the Earth-Moon system, only the gravitational pull of the Earth and the Moon is considered, and in the Earth.

At some point between the Earth and the Moon, the gravitational pull of the Earth and the Moon cancels each other out, and the gravitational force is zero. Between the sun and the earth.

There is also a gravitational equilibrium point.

Manned spacecraft flying around the Earth are generally only a few hundred kilometers above the ground, and space there certainly will not be.

In a zero-gravity environment, even if a spacecraft orbits the Earth at an altitude of 36,000 kilometers, the surrounding space will not be.

Zero gravity, but only light gravity, i.e. gravity is somewhat lighter (less) than on the earth's surface.