The constant companion of our planet not only makes you think about the eternal, but also throws food for thought. Why do we only see one side of the moon if all celestial bodies rotate around its own axis? Maybe this is part of some conspiracy, and on the back of the satellite there is some kind of secret alien base or traces of colonization by an ancient civilization?

How did the moon appear?

The moon is a massive body that has fallen into the zone of action of the Earth's gravity. Exist several theories of its origin:

• It was captured by gravity several billion years ago.
• It was formed as a result of the union of several hundred meteorites that fell under the influence of gravity.
• It is a part of the earth's crust that broke away as a result of a collision with a meteorite.

The most popular theory today is that once there was a collision of the Earth and a small planet with an unstable orbit.

According to another version, the culprit of the cataclysm is a meteorite that passed "on a tangent" and directly beat off part of the earth's crust.

In the first case, the Moon must be part of this same planet. In the second - part of the surface of our planet, under the influence of centrifugal force formed into a sphere.

The whole problem lies in the fact that we are talking about events that took place billions of years ago. Now we cannot tell with certainty about the events of a thousand years ago, what can we say about such colossal terms.

Why doesn't the moon fall to earth?

The moon simultaneously revolves around the earth and around its own orbit. As a result, two forces interact:

Thanks to the interaction of two forces, our eternal companion"can't fly away from us. But it also cannot fall to the surface of the planet, for exactly the same reasons.

If one day this state of equilibrium is disturbed, a terrible cataclysm can occur. But we are talking about cosmic quantities, not a single person is able to influence them. In any case, at the current level of development of science.

Thanks to this pleasant coincidence, the Earth has a satellite. And thanks to another coincidence, in the form of an identical period of rotation around the planet and around its axis, we only see the "bright" side of the moon.

Why does the moon glow at night?

But why is the side facing us always “bright”? After all, the moon does not have its own luminary that would illuminate it according to some kind of schedule.

And to delve into the further description, it is better recall the course of school physics:

1. The sun's rays can reflect off surfaces.
2. After reflection, the angle of propagation of the rays changes.
3. Despite contact with the surface, the reflected light travels further.
4. The ability to reflect depends on the number of rays that continue their path.

At night, the Earth turns to the Sun on the other side, so it gets dark in our hemisphere. But nothing prevents the Moon from contacting the nearest star.

Direct sunlight hits its surface. Part of it remains there, their energy is spent on heating the lunar soil. No wonder its temperature can exceed a hundred degrees.

But a small part of the rays is reflected from the surface and directed in our direction. Thanks to this phenomenon, there is another source of light in the night sky.

Why don't they fly to the moon anymore?

The second half of the last century was marked by real hysteria, in which the two powers were drawn. It's about "lunar race" when Americans and Soviet citizens aspired to the same goal - to be the first to land on the moon.

The United States unconditionally won this competition, which is more offensive - no one Soviet cosmonaut did not set foot on the surface of our satellite. This is despite the fact that humanity first saw the "dark side" precisely thanks to the apparatus made and launched in the Union.

But decades go by, and no one really aspires to the moon anymore.

This is motivated by a number of reasons:

• Lack of funding.
• The main experiments and studies have already been carried out.
• For the coming decades, there is enough surface data to be processed.
• Flights are extremely expensive.
• There is no one else to compete with and thus prove their superiority.

Some of the arguments sound pretty plausible. But, on the other hand, more than one, not even two expeditions were sent to the Moon. There were more. And then everything stopped. And no other country has tried to land to get another reason for pride.

Silent consent, it seems that all countries of the world were able to agree on one issue. Maybe somewhere there, at a distance of about 300 thousand kilometers, there really was a contact with something unknown and humanity was hinted opaquely what further research is fraught with?

These are just conspiracy theories, but after all, after a jerk to the side, all countries “turned on the back” and stopped developing their space programs so actively. Perhaps we are not really welcome there.

The invisible side of the moon

The lunar cycle is 28 days, almost everyone remembers this. The problem is that both periods of rotation fit in 28 days - around the Earth and its own axis. Such a coincidence, but because of it, we are forced to constantly observe only one half of the celestial body.

Due to the current situation, a person will never be able to see the “dark side” while on the surface of the Earth. Actually, it sounds like a challenge. And it will be nice to know that humanity passed this test with dignity.

Thanks to unmanned expeditions, we have photos and detailed maps that "invisible" half. From the point of view of “science for the sake of science”, the achievement is unprecedented, but if you think about practical application received data.

True, there is one positive moment . We made sure that there is no alien lurking behind the moon space fleet that its surface is not littered with someone's bases. Such is the consolation for paranoids and dreamers.

Above natural phenomena I'm either too lazy to think about it, or I don't have time for it. And why we see only one side of the Moon, and because of what the seasons change - this was all once explained, but too long ago.

Video about the position and rotation of the moon

After watching this video, it will become clear to you why the Moon always faces the earth with the same side:

The Moon floats high in the sky, bright, beautiful, with dark spots on a shiny disk. On a full moon, it resembles someone's round, good-natured, slightly mocking face. We always see her like this. And before us, for thousands of years, people looked at the exact same Moon and dark spots were distributed on it in the same way, which make it look like a human face. For thousands of years, people have been observing the changes in her bright face - from the thin sickle of a newborn month to the full radiance of her disk. Meanwhile, the Moon is a ball, the same as other planets, including our Earth, on which we live. But the moon never shows us its other side, we don't see it. Why?

The moon rotates on its axis and at the same time makes its way around the earth, because it is a satellite of the earth.

In twenty-nine and a half days, it makes its revolution around the Earth, and ... it takes the same amount of time to turn around its axis - it makes this revolution so slowly. And that's the whole point. That is why we always see only one side of it.

But how does it happen anyway? To make this clearer to you, let's do a little experiment. Take some small table (if there is no table - a chair or something else that is more convenient for you, what will be at hand). This chair will be an imaginary Earth, and you yourself will be the Moon, which wraps around the Earth. Start moving around the table, staying facing it all the time. At the beginning of your movement, for example, you saw a window in front of you, but then, as you make your circle around the table (that is, the Earth), this window will be behind you, and only at the end of the path you will see it again . This will only confirm that you have turned not only around the table, but also around yourself, your axis.

So is the Moon. It makes a revolution around the Earth and at the same time around its own axis.

But everyone now knows that we still saw the far side of the moon! How did it happen? Do you remember? .. However, no, you don’t remember this: in those years you were still too small! And this happened in 1959, when Soviet scientists launched an automatic station towards the Moon, which flew around our satellite and transmitted images from its other side to us on Earth. And people all over the world saw the far side of the moon for the first time!

And that's not all. A few years later, Soviet scientists again sent an automatic station towards the Moon, and this time again photographs were taken and sent to Earth. Thanks to the images, scientists then compiled the first map of both sides of the lunar surface, and then a new color map of the Moon with lunar seas, mountain ranges, the most important peaks, ring crater mountains, circuses.

While I was writing these pages, one piece of news followed another. Before I had time to tell you about the new color map, an amazing event took place: in February 1966, the world's first automatic station, our Soviet one, landed on the Earth's satellite! She made, as scientists say, a soft landing - this means that she landed on the moon smoothly, without breaking the equipment.

Having gently landed on the moon, the automatic station immediately began to work hard - it sent more and more pictures of the lunar surface, and these pictures were taken at close range. But this is extremely important! The images were large, accurate: scientists simply pounced on these amazing documents, carefully examined them; now they saw what the surface of the moon is like, what is on it, asserted or, on the contrary, changed their points of view about the lunar surface.

"Luna-9" made a soft landing on our satellite - the Moon. And shortly after that, in March 1966, Luna 10 was launched.

She began to fly around the Moon, that is, she became her artificial satellite, and the Luna-10 devices sent messages to Earth that researchers needed to know our celestial neighbor better.

"Luna-10" made its endless flight around the Moon, so close, familiar, and in the early days, the whole world could hear the melody of the communist anthem "The Internationale" coming from it.

After "Luna-10" there were also "Luna-11", and "Luna-12", and "Luna-14", and "Luna-16" ... All the time they soar into space our messengers, they pave the first path to our heavenly neighbor. And always the most difficult and most important thing is what is done for the first time!

However, the news of recent years is amazing! American astronauts, spaceship Apollo 11, Neil Armstrong, Edwin Aldrin and Michael Collins were the first to fly to the moon in July 1969, two of them, Neil Armstrong and Edwin Aldrin, set foot on its surface, the third, Michael Collins, was waiting for them, making circles around the moon .

The names of these cosmonauts will go down in history just like the name of our glorious Gagarin, who was the first to travel into space and see our planet Earth from the outside.

And a very special place in the study of our celestial neighbor is occupied by the amazing apparatus "Lunokhod-4", delivered to the Moon in November 1970. He worked hard there, doing the work of exploring the lunar surface for a man. This amazing apparatus worked only on a lunar day, when it could charge its batteries from the energy of the sun. And on a moonlit night, he rested, as they affectionately said about him: he slept.

Really, it all looks like a fairy tale.

And it may well happen that during the time this book is being printed, new amazing events will occur and we will have to expand this chapter, although at the beginning we were going to tell only about one thing: why we do not see the far side of the moon.

And beautiful, it has attracted the eyes of astronomers since ancient times. Even then, many of its features were noticed: phase changes, the time of sunrise and sunset, the duration lunar month. The ancient scientists also noticed the constancy of the face of the night star. True, in those days they did not wonder why the Moon turned to the Earth on one side. For them, this was the only possible position, fully consistent with the prevailing beliefs about the structure of the sky.

Today things are somewhat different. Our ideas about the movement and interaction of space objects, supported by numerous observations, are very different from those that existed in ancient times. And almost everyone from school knows why the Moon is turned to the Earth on one side.

The beginning of the story

Today, one of the secrets that the Moon stubbornly refuses to reveal to us is its origin. Various studies carried out in order to obtain a definitive answer to this question have so far given rise to several versions. According to one of them, the Moon and the Earth are sisters, formed at about the same time from a common protoplanetary cloud. This is supported by the results of radioisotope analysis, which made it possible to determine the same age of two cosmic bodies. However, there are also data indicating large differences in the composition of our planet and its satellite. A version is put forward to match them: the Moon was formed somewhere far away in space and, approaching the Earth, was captured by it. The hypothesis is also close to it, suggesting that several space objects were attracted, which after a while collided and formed the Moon. Finally, there is a theory according to which our planet is more like a mother for its satellite: the Moon appeared as a result of the collision of the Earth with a huge body. The knocked-out part and subsequently began to orbit around the "progenitor".

"satellite-planet" system

Be that as it may, it is only known for certain that the Moon is a natural satellite of the Earth. According to astronomical data, the night luminary at the time of its formation was located much closer to our planet. Moreover, it circled the Earth faster and turned first one side, then the other. This situation is typical for initial stage evolution of the satellite-planet system. An example of the outcome of the development of such "relationships" is Pluto and Charon accompanying him. Both cosmic bodies are always turned to each other on the same side, their rotation is synchronized. But first things first.

Tidal acceleration

The young Moon immediately began to affect the Earth. This was expressed in the formation of tidal waves in the newly formed oceans, as well as in the crust. This effect has two main implications. First, as a result of some features and its rotation, the tidal wave is ahead of the Moon. The entire mass of our planet, contained in such waves, in turn, affects the satellite, gives it acceleration, and the Moon begins to move faster, gradually moving away from the Earth. Secondly, in this process, an oppositely directed force arises, which slows down the movement of the continents. As a result, the speed of rotation of the Earth around its axis decreases, the length of the day increases.

The moon is moving away from our planet by about 4 cm per year. However, this is not an eternal process, and the probability of the Earth losing its satellite is negligible. The “escape” of the Moon will be completed at the moment when the rotation of the Earth around its axis is synchronized with the movement of the satellite in orbit. In this case, our planet will always look at the night star with the same side.

Similar process

It is easy to assume that the answer to the question of why the Moon is turned to the Earth on one side is associated with a similar phenomenon. Indeed, the Earth causes similar tidal waves in the bowels of the satellite. Since our planet is more massive, the force of its impact is much more tangible. Obeying it, the Moon has long synchronized its rotation with the movement around the Earth. As a result, the always visible and invisible side of the Moon appeared.

Slightly more than half

An attentive amateur astronomer can quickly find out that the face of the night star is still somewhat changing. Visible side The moon does not occupy exactly half of it. The orbit of the night star deviates from the plane of rotation of the Earth around the Sun (the ecliptic) by about 5º. In addition, its axis is displaced by 1.5º relative to the trajectory of the Moon. As a result, up to 6.5º above and below the satellite's poles are available for observation. This process is called the libration of the lunar latitude. Similarly, there is a fluctuation of the longitude of the satellite. It leads to a change in the speed of the moon, depending on the distance from the Earth. Due to this, the part of the satellite hidden from the eyes is reduced, and the other side of the Moon, illuminated, increases to 7º longitude. So it turns out that in total You can observe up to 59% of the lunar surface.

In the distant future

So, the question of why the Moon always looks at the Earth with one side finds the answer in the features of the effect of the planet's gravitational force on the satellite. However, as was said, a similar process after a certain time will lead to the fact that the Earth will also look at the night star with only one of its parts, regardless of what phase the Moon is in. According to the calculations of John Darwin, the grandson of the founder of the theory of evolution, the duration of the day by this moment will be equal to fifty days familiar to us. The distance separating the Earth and the Moon will increase in this case by about one and a half times. This will be the very ideal state of the satellite-planet system.

solar tides

There is, however, some possibility that the Moon is never destined to reach a sufficient distance. The reason for this possibility lies in the solar tides. The daylight has an effect similar to the lunar one both on the planet and on the satellite. If this fact is included in the theoretical construction of the future of two cosmic bodies, it turns out that at a certain distance from the Earth, the Moon will again begin to approach. This shortening of the distance will have devastating consequences. When the Moon is at a distance of 2.9, it will be torn apart by the forces of gravity.

One more "but"

However, this picture may not materialize. The fact is that according to forecasts, the removal of the moon, then its approach and, finally, death will take several trillion years. During this time, a catastrophe of a more serious scale can happen, at least for all life on the planet. The Sun will go out, having exhausted all the reserves of stellar fuel. Following this, all the conditions of interaction in the planetary system of the star will change.

Study

The other side of the moon, inaccessible to direct observation, long time was a mystery, literally shrouded in darkness. It just gave me the opportunity to get to know her better. First aircraft that photographed about 70% of the surface of the hidden part was the Soviet Luna-3. The photographs transmitted to Earth showed that the relief of the reverse side is somewhat different from the nature of the visible surface. There were practically no plains of the seas. Only two such formations were discovered, later named the Sea of ​​Moscow and the Sea of ​​Dreams.

giant crater

In 1965, the Zond-3 spacecraft headed for the moon. He completed the survey of the invisible part of the satellite. The image of the remaining 30% of the surface only confirmed the earlier conclusions: the surface in this part is covered with craters and mountains, but there are practically no seas on it.

The most impressive size is one of the craters, located precisely on the dark side of the moon. Its length is 2250 km, and its depth is 12 km.

Hypotheses

Today, the mysteries are largely unraveled. However, the human mind tends to fantasize about those things and phenomena that are inaccessible to direct observation. Therefore, on the Internet, it is easy to find the most bizarre hypotheses related to the entire Moon as a whole or only to its hidden side. There are suggestions about the artificial origin of the satellite, its population with extraterrestrial intelligence and the deliberate concealment of one of the parties. There are also references to a mysterious space base located on the dark part of the satellite. Such versions are quite difficult both to confirm and to refute. No matter how true or false they are, they are based on the same reason that inspired people to explore space: the hope to find fellow minds in the vast expanses of the Universe, the desire to touch the unknown.

However, today it is quite precisely known why the Moon is turned to the Earth on one side. And the assumption of an artificial origin has not received any serious continuation. The answer to this question has become as obvious as understanding what phase the moon is in today and why. True, it cannot be said that we know everything about the earthly satellite and no discoveries are expected in the future. On the contrary, the night luminary, to match the ancient deities who personified it, remains mysterious and is in no hurry to share secrets. Mankind has yet to learn a lot of interesting things about the satellite of our planet. It is possible that a new stage of study, which began quite recently, will bear fruit in the near future. It is absolutely certain that the implementation of some NASA projects is of great importance in this sense. Among them is "Avatar", which consists in the development of a telepresence suit. It will allow, while on Earth, with the help of robots to conduct experiments on the Moon. Great hopes are also pinned on the colonization project, the implementation of which will result in the deployment of a scientific base on the satellite of our planet.

Everything about everything. Volume 3 Likum Arkady

Why do we only see one side of the moon?

Ever since man appeared on Earth, the Moon has been a mystery to him. In ancient times, people worshiped the moon, considering her the goddess of the night. Today, however, we know much more about what it really is. We can even see the "reverse", or, as it is also called, "dark" side of the Moon in photographs taken by Soviet and American scientists. Why can't we look at the far side of the Moon from Earth? The fact is that the Moon is a natural satellite of the Earth, that is, a celestial body smaller than our planet, revolving around it. One complete orbit of the Moon in orbit around the Earth is approximately 29.5 days.

It is remarkable that the Moon rotates around its axis in the same time. That is why we can see only one side of it from the Earth. To better understand how this happens, try the following experiment. Take an apple or orange and draw a line on it dividing it into two halves. Imagine that this is the moon. Then stretch out a clenched fist in front of you, which should represent the Earth. Now turn the "Moon" with one side to the "Earth". Continuing to keep the "Moon" facing the "Earth" with the same side, make it complete a revolution around the "Earth". You will see that the "Moon" will turn around its axis, and from the "Earth" only one side of it will still be visible.

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The eternal companion of the Earth, surrounded by romantic stories and scientific mysteries - the Moon - is shown as a fixed side 100% of the time. But why can't you see back side Moon, are there mystical facts in the theory or is it easy to explain the process from the point of view of physics and astronomy?

How is the turnover?

The internet is full of photos and videos compiled from them over the course of a year that show exactly how we see the moon. The principles of celestial mechanics will help explain the phenomenon of one side of the cosmic body.

The planet rotates around its own axis and the Sun, and for the Moon, the "sun" becomes the Earth. It revolves around the personal axis and the planet. The speed of a celestial body going around the Earth is 100% the same as the speed of rotation around its own axis.

This means that the Moon rotates 100% synchronously around the planet and around the axis. This was not always the case, and the process of rotation at first looked different. Under the influence of the Earth's gravity and the tides, the planet slowly adjusted the satellite to its own characteristics. This is the reason why the far side of the Moon is not visible.

Practical rotation example

To understand exactly how the turnover occurs, you can conduct a small experiment:

1. Place a chair in the center of the room. This is Earth.
2. Stand at arm's length and place your fingertips in the center of the object. You are the Moon.
3. Start moving so that your fingers do not move. Make a full circle.

Did you notice that you were on one side of the object during the experiment? This also happens with the Earth's satellite.

Do we see exactly half from Earth?

The celestial body makes a complete revolution in only 27 days 7 hours and 43.1 minutes of time. If you look at the video, where the process is recorded for a whole year, it becomes clear that we see more than 50% of the Moon. On the opposite side, 41% of the surface remains inaccessible.

The rotation of the satellite does not always occur at the same speed. Lunar librations occur - when the satellite approaches the Earth at a minimum distance, the speed increases. As the lunar orbit gets farther, the speed slows down. It is also important to understand that celestial bodies rotate along an ellipsoidal trajectory.

More than 4 billion years ago, the Earth and its satellite formed, they rotated faster, and their speeds differed. Now the big planet has adjusted the small one for itself, and this main reason Why is the far side of the moon not visible to the eye.