Do you know why the Moon doesn't fall to Earth?

Surely you have watched the movie "Fall of the Moon». Or read science fiction disaster novels. Or simply looked at the night sky and thought about the eternal. Has the question ever occurred to you: why doesn’t the Moon fall to Earth? Let's figure it out together.

The theory of gravity, formulated by Isaac Newton in the 17th century, describes the rotation of celestial bodies in their orbits, including the movement of the Moon around the Earth. According to it, the force of attraction between two objects is proportional to their masses and inversely proportional to the square of the distance between them.

That is, the Earth attracts The moon with its gravitational force, but it does the same. This interaction is determined by the masses and distance between objects.

If the Moon were hanging motionless in a vacuum, the Earth would pull it with its gravity much stronger and the satellite would fall onto our planet. So-so option.

But the moon, fortunately, moves around the Earth, and at a significant speed - 1.023 km/s. This provides the necessary inertia - the property of an object to maintain its state of motion if no other forces act on it. Thanks to her Moon remains in its orbit.

If our satellite were moving slower, the Earth's gravity would prevail over its movement and it would fall onto it. If the Moon did this faster, it would break out of orbit and fly into space.

Where does the Moon have such inertia that it has been rotating in Earth’s orbit for billions of years and is fine? Well, to answer we need to remember how our satellite was formed.

According to modern ideas (the so-called giant impact theory), the Moon arose when a large object approximately the size of Mars crashed into the Earth. This happened about 4.5 billion years ago. As a result, the Earth and the celestial body that collided with it (planet Theia) merged into one planet, where we are now we live.

The force of the impact was so great that the ejected debris never fell back, but collected in orbit and formed the Moon. Check out this NASA animation to get a better idea of ​​what it looked like. In reality the process is like claim scientists, took only a few hours.

Fortunately, at that moment there was no one on Earth yet (life had not arisen then), so all these fascinating events on a cosmic scale took place without us. We we observe only the result of the collision is the Moon.

According to the law of conservation of motion, if an object is not acted upon by external forces, then its momentum (the product of mass and speed) is conserved. And since there is no significant resistance or friction in outer space, the Moon continues to move by inertia and moves around the Earth in its orbit.

For that matter, the satellite is not going to fall on our planet, but, on the contrary, gradually flies away into the space. Earth's powerful gravity slows it down rotation around its own axis - this is called tidal interaction. Because of this, the Moon is moving away from the Earth at a rate of approximately 3.8 cm per year. In billions of years, our satellite will most likely fly away, but by that time the planet will already be uninhabitable due to rising solar temperatures.

So don't worry, the moon will definitely not fall on us.