Does the Moon rotate around its axis: how does the Moon rotate

The moon accompanies our planet in its great space journey for several billion years. And it shows us, earthlings, from one century to the other, always the same lunar landscape. Why do we admire only one side of our companion? Does the Moon rotate around its axis, or does it soar in outer space?

Characteristics of our space neighbor

In the solar system, satellites are much larger than the Moon. Ganymede is a satellite of Jupiter, for example, twice as heavy as the Moon. But it is the biggest satellite relative to the mother planet. Its mass is more than a percent of the earth's, and its diameter is about a quarter of the earth's. There are no more such proportions in the solar family of planets.

Let's try to answer the question of whether the Moon rotates around its axis, looking more attentively to our closest space neighbor. According to the theory accepted in scientific circles, our planet acquired a natural satellite as a protoplanet - not completely cooled, covered by the ocean of liquid red-hot lava, as a result of a collision with another planet, smaller in size. Therefore, the chemical compositions of the lunar and terrestrial soils are slightly different - the heavy nuclei of the colliding planets have merged, which is why the earth's rocks are richer in iron. The moon got the remains of the upper layers of both protoplanets, there is more stone.

Does the Moon rotate?

To be precise, the question of whether the Moon rotates is not entirely correct. After all, like any satellite in our system, it turns around the mother planet and, along with it, is spinning around the star. But, the axial rotation of the moon is not quite usual.

No matter how much you look at the moon, it is always turned to us by the crater of Tycho and the sea of Tranquility. "And does the Moon rotate around its axis?" - from century to century the Earthmen asked themselves a question. Strictly speaking, if you operate with geometric concepts, the answer depends on the chosen coordinate system. Relative to the Earth, the axial rotation of the moon is indeed absent.

But from the point of view of the observer located on the Sun-Earth line, the axial rotation of the Moon will be clearly visible, and one polar revolution to a fraction of a second will be equal in duration to the orbital one.

It is interesting that this phenomenon in the solar system is not unique. So, the satellite of the dwarf planet Pluto Charon always looks at his planet one side, the same way the satellites of Mars - Deimos and Phobos.

In scientific terms, this is called synchronous rotation or tidal capture.

What is the tide?

In order to understand the essence of this phenomenon and confidently answer the question of whether the Moon rotates around its own axis, it is necessary to disassemble the essence of tidal phenomena.

Imagine two mountains on the surface of the Moon, one of which "looks" directly to Earth, the other is at the opposite point of the moon's sphere. Obviously, if both mountains were not part of one celestial body, but rotated around our planet on their own, their rotation could not be synchronous, the one that is closer, according to the laws of Newtonian mechanics, should rotate faster. That is why the masses of the moon ball, located in opposite points towards the Earth, tend to "run away from each other".

How the moon "stopped"

How tidal forces act on this or that celestial body, it is convenient to disassemble on the example of our own planet. We, too, revolve around the Moon, or rather the Moon and Earth, as in astrophysics, "lead a round dance" around the physical center of the masses.

As a result of the action of tidal forces, the level of water covering the Earth rises both in the nearest and the most remote point from the satellite. And the maximum amplitude of the tide can reach 15 or more meters.

Another feature of this phenomenon is that these tidal "humps" circumnavigate the surface of the planet every day against its rotation, creating friction at points 1 and 2, and thus slowly stopping the globe in its rotation.

The impact of the Earth on the moon is much stronger because of the difference in mass. And although there is no ocean on the Moon, the tidal forces act no worse to the rocks. And the result of their work is obvious.

So does the Moon rotate around its axis? The answer is yes. But rotation is closely related to the movement around the planet. Tidal forces for millions of years aligned the axial rotation of the Moon with the orbital.

And what about the Earth?

Astrophysicists claim that right after the big collision that caused the formation of the moon, the angular velocity of rotation of our planet was much greater than now. The day lasted no more than five hours. But as a result of the friction of tidal waves on the ocean floor year after year, millennium after millennium, the rotation slowed, and the present day lasts 24 hours.

On average, every century adds to our days for 20-40 seconds. Scientists suggest that in a couple of billion years, our planet will look at the Moon as well as the Moon on it, that is, one side. The truth of this, most likely, will not happen, since even earlier the Sun, turning into a red giant, will "swallow" both the Earth and its faithful companion - the Moon.

By the way, the tidal forces give Earthlings not only an increase and a decrease in the level of the world ocean in the equatorial region. By influencing the masses of metals in the earth's core, deforming the hot center of our planet, the Moon helps maintain it in a liquid state. And thanks to the active liquid core, our planet has its own magnetic field, which protects the entire biosphere from the murderous solar wind and deadly cosmic rays.