Today we can go outside our home in the early morning or evening and see a bright space station flying overhead. Although space travel has become an everyday part of the modern world, for many people, space and the issues associated with it remain a mystery. So, for example, many people do not understand why the satellites do not fall to Earth and do not fly into space?
Elementary physics
If we throw the ball into the air, it will soon return to Earth, like any other object, such as an airplane, a bullet or even a balloon.
To understand why a spaceship is able to rotate around the Earth without falling, at least under normal circumstances, you need to conduct a thought experiment. Imagine that you are on a planet similar to Earth, but there is no air or atmosphere on it. We need to get rid of air so that we can make our model as simple as possible. Now, you have to mentally climb to the top of a high mountain with a cannon to understand why the satellites do not fall to Earth.
Let's put an experiment
We aim the gun barrel horizontally and shoot towards the western horizon. The projectile will fly out of the barrel with great speed and head west. As soon as the shell leaves the barrel, it will begin to approach the surface of the planet.
As the cannon ball moves rapidly west, it will fall to the ground at some distance from the top of the mountain. If we continue to increase the power of the gun, the projectile will fall to the ground much further from the place of the shot. Since our planet has the shape of a ball, every time a bullet flies out of the barrel, it will fall further, because the planet also continues to rotate around its axis. This is why satellites do not fall to Earth under the influence of gravity.
Since this is a thought experiment, we can make a pistol shot more powerful. In the end, we can imagine a situation in which a projectile moves at the same speed as the planet.
At this speed, without the air resistance that slows it down, the projectile will continue to rotate around the Earth forever, as it will continuously fall toward the planet, but the Earth will also continue to fall at the same speed, as if "escaping" from the projectile. This condition is called free fall.
On practice
In real life, everything is not as simple as in our thought experiment. Now we have to deal with air resistance, which causes a slowdown in the velocity of the projectile, ultimately depriving it of the speed it needs in order to stay in orbit and not to fall to Earth.
Even at a distance of several hundred kilometers from the Earth’s surface, there is still some air resistance that acts on satellites and space stations and slows them down. This resistance ultimately causes the spacecraft or satellite to fall into the atmosphere, where they usually burn out due to friction with the air.
If space stations and other satellites did not have acceleration capable of pushing them higher in orbit, they would all fall to Earth unsuccessfully. Thus, the speed of the satellite is regulated so that it falls on the planet at the same speed as the planet moves in a curve in the direction from the satellite. That is why satellites do not fall to Earth.
Planetary interaction
The same process applies to our Moon, which moves in orbit around the Earth. Every second, the Moon approaches approximately 0.125 cm to the Earth, but at the same time, the surface of our spherical planet moves at the same distance, dodging the Moon, therefore they remain in their orbits relative to each other.
There is nothing magical about orbits and such a phenomenon as free fall - they only explain why the satellites do not fall to Earth. It is just gravity and speed. But this is incredibly interesting, however, like everything else related to space.