Why doesn't the moon rotate and we only see one side? June 18th, 2018
As many have already noticed, the Moon always faces the same side towards the Earth. The question arises: is the rotation of these celestial bodies around their axes synchronous relative to each other?
Although the Moon rotates around its axis, it always faces the Earth with the same side, that is, the Moon’s revolution around the Earth and its rotation around its own axis are synchronized. This synchronization is caused by the friction of the tides that the Earth produced in the Moon's shell.
Another mystery: does the Moon rotate on its axis at all? The answer to this question lies in resolving the semantic problem: who is at the forefront - an observer located on Earth (in this case, the Moon does not rotate around its axis), or an observer located in extraterrestrial space (then the only satellite of our planet rotates around its axis).
Let's carry out this simple experiment: draw two circles of the same radius, touching each other. Now imagine them as disks and mentally roll one disk along the edge of the other. In this case, the rims of the discs must be in continuous contact. So, how many times do you think the rolling disk will turn around its axis, making a full revolution around the static disk. Most will say once. To test this assumption, let's take two coins of the same size and repeat the experiment in practice. So what's the result? A rolling coin has time to turn around its axis twice before it makes one revolution around a stationary coin! Surprised?
On the other hand, does a rolling coin rotate? The answer to this question, as in the case of the Earth and the Moon, depends on the observer's frame of reference. Relative to the initial point of contact with the static coin, the moving coin makes one revolution. Relative to an outside observer, during one revolution around a stationary coin, a rolling coin turns twice.
Following the publication of this coin problem in Scientific American in 1867, the editors were literally inundated with letters from indignant readers who held the opposite opinion. They almost immediately drew a parallel between the paradoxes with coins and celestial bodies (Earth and Moon). Those who held the point of view that a moving coin, in one revolution around a stationary coin, manages to turn around its own axis once, were inclined to think about the inability of the Moon to rotate around its own axis. The activity of readers regarding this problem increased so much that in April 1868 it was announced that the debate on this topic was ending in the pages of the Scientific American magazine. It was decided to continue the debate in the magazine The Wheel, specially dedicated to this “great” problem. At least one issue came out. In addition to illustrations, it contained various drawings and diagrams of intricate devices created by readers in order to convince editors that they were wrong.
Various effects generated by the rotation of celestial bodies can be detected using devices like the Foucault pendulum. If it is placed on the Moon, it will turn out that the Moon, rotating around the Earth, rotates around its own axis.
Can these physical considerations serve as an argument confirming the rotation of the Moon around its axis, regardless of the observer’s frame of reference? Oddly enough, but from the point of view general theory relativity probably not. We can generally assume that the Moon does not rotate at all, it is the Universe that rotates around it, creating gravitational fields like the Moon rotating in still space. Of course, it is more convenient to take the Universe as a stationary frame of reference. However, if you think objectively, regarding the theory of relativity, the question of whether this or that object really rotates or is at rest is generally meaningless. Only relative motion can be “real”.
To illustrate, imagine that the Earth and Moon are connected by a rod. The rod is fixed on both sides rigidly in one place. This is a situation of mutual synchronization - both one side of the Moon is visible from the Earth, and one side of the Earth is visible from the Moon. But this is not the case here; this is how Pluto and Charon rotate. But we have a situation where one end is rigidly fixed to the Moon, and the other moves along the surface of the Earth. Thus, one side of the Moon is visible from the Earth, and different sides of the Earth are visible from the Moon.
Instead of a barbell, the force of gravity acts. And its “rigid attachment” causes tidal phenomena in the body, which gradually either slow down or speed up the rotation (depending on whether the satellite is rotating too quickly or too slowly).
Some other bodies in the Solar System are also already in such synchronization.
Thanks to photography, we can still see more than half of the surface of the Moon, not 50% - one side, but 59%. There is a phenomenon of libration - the apparent oscillatory movements of the Moon. They are caused by orbital irregularities (not ideal circles), tilts of the rotation axis, and tidal forces.
The Moon is tidally locked into the Earth. Tidal locking is a situation when the period of revolution of a satellite (Moon) around its axis coincides with the period of its revolution around the central body (Earth). In this case, the satellite always faces the central body with the same side, since it rotates around its axis in the same time that it takes for it to orbit around its partner. Tidal locking occurs during the process of mutual motion and is characteristic of many large natural satellites of the planets of the Solar System, and is also used to stabilize some artificial satellites. When observing a synchronous satellite from the central body, only one side of the satellite is always visible. When observed from this side of the satellite, the central body “hangs” motionless in the sky. From the opposite side of the satellite, the central body is never visible.
Facts about the moon
There are lunar trees on Earth
Hundreds of tree seeds were carried to the Moon during the 1971 Apollo 14 mission. Former employee US Forest Service (USFS) Stuart Roosa took the seeds as personal cargo as part of a NASA/USFS project.
Upon returning to Earth, these seeds were germinated and the resulting lunar seedlings were planted throughout the United States as part of the country's bicentennial celebrations in 1977.
There is no dark side
Place your fist on the table, fingers down. You see the back of it. Someone on the other side of the table will see your knuckles. This is roughly how we see the Moon. Because it is tidally locked to our planet, we will always see it from the same perspective.
The concept of the “dark side” of the moon came out of popular culture - remember the album Pink Floyd 1973's "Dark Side of the Moon" and the 1990 thriller of the same name - and actually means the far, night side. The one we never see and which is opposite to the side closest to us.
Over a period of time, we see more than half of the Moon, thanks to libration
The Moon moves along its orbital path and moves away from the Earth (at a rate of about one inch per year), accompanying our planet around the Sun.
If you were to zoom in on the Moon as it speeds up and slows down during this journey, you would also see that it wobbles from north to south and west to east in a motion known as libration. As a result of this movement, we see part of the sphere that is usually hidden (about nine percent).
However, we will never see another 41%.
Helium-3 from the Moon could solve Earth's energy problems
The solar wind is electrically charged and occasionally collides with the Moon and is absorbed by rocks on the lunar surface. One of the most valuable gases found in this wind and absorbed by the rocks is helium-3, a rare isotope of helium-4 (commonly used for balloons).
Helium-3 is ideal for meeting reactor needs thermonuclear fusion followed by energy generation.
One hundred tons of helium-3 could satisfy the Earth's energy needs for a year, according to Extreme Tech's calculations. The surface of the Moon contains about five million tons of helium-3, while on Earth there is only 15 tons.
The idea is this: we fly to the Moon, extract helium-3 in a mine, put it in tanks and send it to Earth. True, this may not happen very soon.
Is there any truth to the myths about the madness of the full moon?
Not really. The assumption is that the brain is one of the most watery organs human body, is influenced by the moon, has its roots in legends that go back several thousand years, dating back to the time of Aristotle.
Because the Moon's gravitational pull controls the tides earth's oceans, and humans are 60% water (and 73% brain), Aristotle and the Roman scientist Pliny the Elder believed that the Moon should have a similar effect on ourselves.
This idea gave rise to the term "lunar madness", "Transylvanian effect" (which became widespread in Europe during the Middle Ages) and "lunar madness". 20th century films that linked the full moon with psychiatric disorders added particular fuel to the fire. car accidents, murders and other incidents.
In 2007, the government of the British seaside town of Brighton ordered additional police patrols during full moons (and on paydays too).
And yet science says there is no statistical connection between people's behavior and full moon, according to several studies, one of which was conducted American psychologists John Rotton and Ivan Kelly. It is unlikely that the Moon affects our psyche; rather, it simply adds light, in which it is convenient to commit crimes.
Missing moon rocks
In the 1970s, Richard Nixon's administration distributed rocks recovered from the lunar surface during the Apollo 11 and Apollo 17 missions to leaders of 270 countries.
Unfortunately, more than a hundred of these stones have gone missing and are believed to have ended up on the black market. While working for NASA in 1998, Joseph Gutheinz even conducted a covert operation called "Lunar Eclipse" to stop the illegal sale of these stones.
What was all the fuss about? A pea-sized piece of moon rock was valued at $5 million on the black market.
The moon belongs to Dennis Hope
By at least he thinks so.
In 1980, exploiting a loophole in the 1967 UN Space Ownership Treaty that "no country" could lay claim to the solar system, Nevada resident Dennis Hope wrote to the UN and claimed the right to private property. They didn't answer him.
But why wait? Hope opened a lunar embassy and began selling one-acre lots for $19.99 each. For the UN solar system is almost the same as the world's oceans: outside the economic zone and belonging to every inhabitant of the Earth. Hope claimed to have sold extraterrestrial properties to celebrities and three former US presidents.
It is unclear whether Dennis Hope really does not understand the wording of the treaty or whether he is trying to force the legislature to make a legal assessment of its actions so that the development of celestial resources can begin under more transparent legal conditions.
Sources:
To the question Why do we see only one side of the Moon asked by the author User deleted the best answer is
Reply from Flush[guru]
tak ten ot zemli padayet na lunu i ona zatmevayetsya
Reply from Gray hair[guru]
Since man appeared on Earth, the Moon has been a mystery to him. In ancient times, people worshiped the Moon, considering her to be 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, the “dark” side of the Moon in photographs taken by Soviet and American scientists. Why are we unable to look at the far side of the Moon from Earth? The fact is that the Moon is natural satellite Earth, that is, the smaller celestial body.
sizes than our planet orbiting around it. One full revolution 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 amount of time. That is why from the Earth we can only see one side of it.
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 extend a clenched fist in front of you, which should represent the Earth. Now turn the “Moon” with one side towards the “Earth”. Continuing to keep the “Moon” facing the “Earth” with the same side, make a complete revolution around the “Earth”. You will see that the “Moon” will turn around its axis, and from the “Earth” there will be still only one side of it is visible.
Reply from skinny[guru]
it's all about how the sun illuminates it.
Reply from Yoshiko[guru]
I'm still wondering how this happens lunar eclipses. I understand the sun: the moon covered the sun. And what covers the moon, there is nothing between us.
Reply from ~Messenger of Heaven~[guru]
By the way, I heard this version: on the other side of the moon there is a base of UFO ships. people tried to fly there, but they won’t let us in
Reply from Dmitry Chirkov[guru]
rotation periods coincide
Reply from Kenshi Hemuro[guru]
Because the moon does not rotate on its axis
Reply from Pavel Kulikov[newbie]
Since this is the good side, and the evil one hides behind it and feeds power from the shadows))) XD
Reply from Destroyer[newbie]
link
Why on visible side There are more craters on the moon than on the back
side?
Hypothesis.
After a massive bombardment by meteorites, the Moon's center of gravity changed.
The more massive side of the Moon entered gravitational
interaction with the Earth. The tumbler principle.
The moon stopped rotating, only vibrations called
– libration.
Reply from Alexander Green[guru]
this is how nature wanted it, why is not our business, why is it not for us to judge
Reply from Kghhy grfgf[newbie]
The period of the Moon's revolution around the Earth, when it occupies a consistently identical position among the stars when observed from the Earth, is called a sidereal month. It is 27.3 days. The rotation of the Moon around its axis occurs at a constant angular velocity in the same direction in which it revolves around the Earth. The period of rotation of the Moon around its axis is equal to the period of its revolution around the Earth - 27.3 days. That is why from the Earth we see only one hemisphere, which is called the visible hemisphere, and the other, hidden from our eyes, the invisible hemisphere is called reverse side Moons.
Reply from Oleg Pestryakov[guru]
Regardless of whether we see the Moon at full moon, when it is illuminated by the Sun, or when it is partially or completely in shadow, the Moon always faces the Earth with one side. Moving around the Earth along a complex trajectory and returning to old place approximately once every 11 years, the Moon simultaneously rotates around its axis so that one of its sides is always turned towards the Earth. This probably happens because the center of mass of the Moon is shifted towards the Earth and does not allow it to rotate freely. It even sways like a roly-poly, thanks to which from the Earth you can see slightly more of the surface of the Moon than half of it. It was possible to look at the other side for the first time on October 7, 1959 (7/X/1959), when the Soviet automatic interplanetary station Luna-3 successfully photographed the far side of the Moon. This is what the first image of the Moon looks like, taken on October 7, 1959 by the Luna-3 station. Not very high quality, but it was the first... View of the Moon from the reverse side. Strictly speaking, the Moon is very slowly, but still moving away from the Earth, and in a few hundred million years it may leave it if humanity does not want to hold on to it by that time and does not learn to correct its orbit...
Eternal companion of the Earth, surrounded romantic stories and scientific mysteries, - the Moon is shown with a fixed side 100% of the time. But why the far side of the Moon is not visible, the theory contains mystical facts or is it easy to explain the process from the point of view of physics and astronomy?
The Internet is full of photos and videos compiled from them throughout the year that show exactly how we see the Moon. The principles of celestial mechanics will help explain the phenomenon of one side of a cosmic body.
The planet rotates around its own axis and the Sun, and for the Moon the Earth becomes the “sun”. It rotates around its personal axis and the planet. The speed of a celestial body's orbit around the Earth corresponds 100% to the speed of rotation around its own axis.
This means that the Moon rotates 100% synchronously both around the planet and around its axis. This was not always the case, and the rotation process looked different at first. Under the influence of Earth's gravity and tides, the planet slowly adjusted the satellite to own characteristics. This is the reason why the far side of the Moon is not visible.
To understand exactly how turnover occurs, you can conduct a small experiment:
Did you notice that you were standing with one side to the object during the experiment? This also happens with the Earth's satellite.
Full turn the celestial body takes 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 satellite does not always rotate 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 further away, the speed slows down. It is also important to understand that they rotate celestial bodies along an ellipsoidal trajectory.
More than 4 billion years ago, the Earth and its satellite were formed, they rotated faster, and their speeds were different. Now big planet adjusted the little one for herself, and this main reason, why the far side of the Moon is not visible to the eye.
The moon is also called the goddess of the night. This is our silent neighbor, there is no life on it. It orbits the Earth at a distance of 384,400 kilometers (238.618 miles). A complete revolution of the Moon around the Earth takes 27 days and 12 hours. This fact is especially significant; it means that we will never be able to see the other side of the Moon. Scientists have calculated that the Moon should rotate around its axis much faster. But under the influence of the force of gravity, the speed of its rotation decreases, due to which the Moon’s own rotation is correlated with its movement around the Earth. This is why we always see only one side of the Moon.
The length of day and night on the Moon does not change. The lunar day lasts approximately 14 days, and the night lasts the same amount. During day and night on the Moon, the temperature changes greatly. It reaches about 120 degrees during the day and freezing temperatures at night. That is why the American astronauts who were the first to walk on the Moon had special suits - spacesuits that protected them from the heat.Neil Armstrong was the first to set foot on the moon. “This small step for man is a huge step for humanity,” he said as he descended on the surface of the Moon. This amazing event occurred on July 15, 1969. Millions of viewers could see it with their own eyes on television. Through satellite television lines, images from the Moon reached the most remote areas of the Earth.
Why is there no life on the Moon?
Now that man has carefully explored the surface of the Moon, he has learned a lot of interesting things about it. But man knew the fact that there is no life on the Moon long before he reached the Moon. The Moon has no atmosphere. Astronomers have established this because there is no twilight or sunset on the Moon. On Earth, night comes gradually because the air reflects the sun's rays even after sunset. On the Moon it is completely different: one moment it was light, and at one moment it was dark. The absence of an atmosphere means that the Moon is not protected from any solar radiation. The sun emits heat, light and radio waves. Life on Earth depends on this heat and light.
But the Sun also emits harmful radiation. The earth's atmosphere protects us from it. And on the Moon there is no atmosphere that could absorb this harmful radiation. And all the sun's rays, beneficial and harmful, safely reach the surface of the Moon.
Because there is no atmosphere, the surface of the Moon is either extremely hot or extremely cold. The Moon rotates, and the side facing the Sun becomes very hot. Temperatures can reach over 150 degrees Celsius. This is hot boiling water. A hot lunar day lasts for two weeks.It is followed by night, which also lasts two weeks. At night, temperatures drop to 125 degrees below zero. This is twice colder than the temperature observed at the North Pole.Under such conditions, none of the life forms known on Earth can exist.
The Moon is a natural satellite of the Earth, located at a distance of about 384,000 km (239,000 miles). The moon is much lighter and smaller than Earth. It takes 29 days to orbit the Earth. The Moon does not emit its own light, but only reflects the light of the Sun. As the Moon travels around the Earth, it appears to us in different forms. These various shapes we call the phases of the moon. They are obtained as a result of the fact that, as the Earth rotates around the Sun, it shades the Moon in different ways. The moon reflects different amounts of light depending on this.
The same side of the Moon always faces the Earth. Until 1959, when the Luna 3 satellite photographed the far side of the Moon, we did not know what its other hemisphere looked like.
The moon is made of solid rock. Thousands of craters are visible on its surface. There are vast, flat, dusty plains and high mountains. It is possible that the craters were formed from bubbles that burst in the lunar crust as a result of volcanic activity millions of years ago. In orbit around the Earth, the Moon is held by the force of gravity. The gravity on the Moon is 6 times less than on Earth. From time to time, the water of the Earth's oceans rushes towards the Moon. This causes hot flashes.
Now that people have already visited the Moon, they have a concrete idea of the Earth’s satellite and, accordingly, can plan the construction of stations on this planet. Of course, living conditions there are quite difficult. The surface of the Moon is literally pitted with huge craters, there are also quite high mountains, large seas of frozen volcanic lava. Once upon a time there were volcanic eruptions on the Moon, but today they are no longer active. The seas and the inner surface of the craters are covered with a thick layer of dust. There is no air, no water, no animals, no plants. Not a sound can be heard on the Moon, since sounds travel thanks to air molecules. Therefore, people need a special spacesuit to move on the Moon. Human habitations on the Moon must be absolutely sealed, like bathyscaphes for underwater research. Everything that is necessary to maintain life, right down to the air itself, must be delivered from the Earth.
The Moon floats high in the sky, bright, beautiful, with dark spots on its 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 the 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 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 you and I live. But the Moon never shows us its other side, we do not see it. Why?
The Moon rotates around 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 completes its revolution around the Earth, and... it takes the same amount of time to turn around its axis - so slowly does it complete this revolution. And that's the whole point. That's why we always see only one side of her.
But how does this happen? So that you can imagine this more clearly, 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, that will be at hand). This chair will be the imaginary Earth, and you yourself will be the Moon, which revolves around the Earth. Start moving around the table, remaining facing it the entire 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 will you see it again . This will only confirm that you have turned not only around the table, but also around yourself, your axis.
That's how the Moon is. It rotates around the Earth and at the same time around its own axis.
But everyone now knows that we finally saw the far side of the Moon! How did this happen? Do you remember?.. However, no, you don’t remember this: in those years you were still too young! And this happened in 1959, when Soviet scientists launched an automatic station towards the Moon, which flew around our satellite and transmitted images from the 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, major peaks, ring crater mountains, circuses.
While I was writing these pages, one news followed another. Before I had time to tell you about the new color map, an amazing event happened: in February 1966, the world’s first automatic station, ours, the 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 softly 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 and accurate: scientists simply pounced on these amazing documents and looked at them carefully; Now they saw what the surface of the Moon was like, what was on it, they affirmed 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 soon after that, in March 1966, Luna 10 was launched.
She began to fly around the moon, that is, she became her artificial satellite, and Luna-10’s instruments sent messages to Earth that research scientists needed to better know our celestial neighbor.
“Luna-10” made its endless flight around the Moon, so close and familiar, and in the first 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”... Our messengers are constantly soaring into outer space, they are paving the first paths to our heavenly neighbor. And the most difficult and most important thing is always what is done for the first time!
However, the news recent years 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, stepped 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 go 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 Lunokhod-4 apparatus, delivered to the Moon in November 1970. He worked hard there, doing man's work to explore the lunar surface. This amazing device only worked on a lunar day, when it could charge its batteries from solar energy. A moonlit night Oh, he was resting, as they affectionately said about him: he was sleeping.
Really, all this 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 even more, although at first we were going to talk about only one thing: why we don’t see the far side of the Moon.