In the night sky, we see the only satellite of the Earth that accompanies our planet. We usually only see it at night. But why does not the Moon fall to the Earth, what keeps it in the sky?
The scientific explanation for the question "Why doesn't the moon fall?"
The moon is not firmly attached to the globe. It revolves around our planet. Therefore, on different days we see different forms of our natural satellite. Sometimes he appears in the cloudless sky in the evening, and sometimes - late at night. We say that the month rises and sets, that today is the full moon, and in 20 days there will be a new moon. But it is difficult to answer the question "Why the Moon does not fall". Indeed, according to Newton's law, an attractive force acts on any body, and it must fall.
The moon is influenced by the earth and the sun. They pull her in two directions. But the attraction from the main luminary is much stronger than from our planet. Therefore, the Moon and Earth revolve around the center of the Universe, but at the same time they are next to each other. If only the Sun acted on the Moon, then it would move along a route with strongly concave points. But our planet also affects it. Its action in comparison with the action of a powerful luminary is much smaller, but the Earth is closer to a month. Therefore, our planet aligns the trajectory of its satellite, changing it from time to time.
It turns out that the moon is attracted by two large celestial bodies. But this is not enough to keep her from falling. It doesn't fall because it moves. Its speed is 1 km / sec. This is enough not to fall, but not enough to stay in its orbit. If the night star can stop something, then it will fall on earth surface.
The answer to the question "Why does the moon not fall to the Earth?"
The attraction of two bodies, movement in Space - all this can be easily modeled. Try it - and you will understand why the Moon cannot fall to the Earth. The answer can be obtained with a little and very simple experience. Take an item that you can easily attach to a string. Tie it well and start twisting. Now your subject is spinning pretty fast. He does not fall, he does not fly anywhere. The thread is the force of attraction. Your hand is the Earth. The subject on a string is the Moon. The movement does not allow it to fall, get out of orbit, and the thread does not allow it to fly away from you. If the thread breaks, the object will fly off. So it is with the moon. When the planet's gravitational force weakens, the night star will fly away into distant Space.
Another experiment will help to understand the way the satellite of our planet moves. Take an apple. Unclench your hand - it will fall. Newton's force is at work. Take the apple again and try to throw it parallel to the surface. The apple will fly by for a while and fall. What if we throw an apple on a big globe? Then parallel to him? Then the apple will fly over the globe and fall somewhere else. And if the globe attracts, then the apple will fly parallel to its surface.
Why doesn't the moon fall on the sun?
If the Sun is stronger than the Earth, then why does the Moon not fall on? Why is the power of the center of the Universe not able to attract this night star to itself? Capable. The sun's attraction is twice as strong as the earth's. But our planet does not allow the Moon to fall on the Sun. Although she attracts the moon to herself weaker, she is next to her. This proximity compensates for the influence of the sun. And the month does not fly away from its orbit to fall on the solar surface.
Distance balances two different forces of attraction. But scientists prove that the moon is getting farther from us every year. A month moves away from the Earth by 3-4 cm per year. This is imperceptible on the scale of human life. However, the further the satellite moves away from the Earth, the less force our planet will exert on it, and the influence of the Sun will increase.
So far, the only satellite of our planet revolves around us, and the Earth, together with its satellite, revolves around the Sun. The solar power is spent on the fact that these two bodies do not move in a straight line, but go along a curved orbit. For more power, the daylight is not enough.
Why doesn't the moon fall to earth? Short answer
3 points of the answer “Why doesn't it fall to the Earth?”:
1. It is held by gravity. If it is not there, the Moon will fly away into the open space.
2. From falling to the Earth, the Moon is protected by the solar attraction. The power of this star is twice as strong, but our satellite is closer to its planet. This equalizes the impact of the two large bodies.
3. Movement prevents the Moon from falling. If it stops, it will fall to the earth's surface.
Even if we assume that the night star has stopped and began to fall on the earth's surface, then a huge energy will be released, which will destroy the month. As a result, our satellite will cease to be a solid body.
Ministry of Education of the Russian Federation
MOU "Secondary school with. Solodniki ".
abstract
on the topic of:
Why doesn't the moon fall to earth?
Completed by: Pupil 9 Cl,
Feklistov Andrey.
Checked:
Mikhailova E.A.
S. Solodniki 2006
1. Introduction
2. The law of universal gravitation
3. Can the force with which the Earth attracts the moon be called the weight of the moon?
4. Is there centrifugal force in the Earth-Moon system, what does it act on?
5. Around what does the moon revolve?
6. Can the Earth and the Moon collide? Their orbits around the Sun intersect, and even more than once
7. Conclusion
8. Literature
Introduction
The starry sky at all times occupied the imagination of people. Why do stars light up? How many of them shine in the night? Are they far from us? Does the stellar universe have boundaries? Since ancient times, people have pondered these and many other questions, sought to understand and comprehend the structure of that big worldin which we live. This opened up the broadest area for the study of the Universe, where the forces of gravity play a decisive role.
Among all the forces that exist in nature, the force of gravity differs, first of all, in that it manifests itself everywhere. All bodies have mass, which is defined as the ratio of the force applied to the body to the acceleration that the body acquires under the action of this force. The force of attraction acting between any two bodies depends on the masses of both bodies; it is proportional to the product of the masses of the bodies under consideration. In addition, the force of gravity is characterized by the fact that it obeys the law inversely proportional to the square of the distance. Other forces may depend on distance in a very different way; many such forces are known.
All weighty bodies mutually experience gravitation, this force determines the movement of the planets around the sun and satellites around the planets. The theory of gravity, a theory created by Newton, stood at the cradle of modern science. Another theory of gravity, developed by Einstein, is the greatest achievement of theoretical physics in the 20th century. During the centuries of human development, people observed the phenomenon of mutual attraction of bodies and measured its magnitude; they tried to put this phenomenon in their service, to surpass its influence, and, finally, already in the very recent times calculate it with extreme accuracy during the first steps deep into the universe
The story is widely known that the fall of an apple from a tree brought about the discovery of Newton's law of universal gravitation. We do not know how reliable this story is, but the fact remains that the question: “why does the moon not fall to the earth?” Interested Newton and led him to the discovery of the law of universal gravitation. The forces of gravity are otherwise called gravitational.
The law of universal gravitation
Newton's merit lies not only in his ingenious guess about the mutual attraction of bodies, but also in the fact that he was able to find the law of their interaction, that is, the formula for calculating gravitational force between two bodies.
The law of universal gravitation says: any two bodies are attracted to each other with a force directly proportional to the mass of each of them and inversely proportional to the square of the distance between them
Newton calculated the acceleration imparted to the Moon by the Earth. The acceleration of freely falling bodies near the earth's surface is 9.8 m / s 2... The moon is distant from the Earth at a distance equal to about 60 Earth radii. Therefore, Newton reasoned, the acceleration at this distance will be:. The moon, falling with such an acceleration, should approach the Earth in the first second by 0.27 / 2 \u003d 0.13 cm
But the Moon, in addition, also moves by inertia in the direction of instantaneous velocity, i.e. along a straight line tangent at a given point to its orbit around the Earth (Fig. 1). Moving by inertia, the Moon should move away from the Earth, as the calculation shows, in one second by 1.3 mm.Of course, we do not observe such a movement in which the Moon would move along the radius to the center of the Earth in the first second, and tangentially in the second second. Both movements add up continuously. The moon moves along a curved line close to a circle.
Let us consider an experiment from which it is seen how the force of attraction acting on a body at right angles to the direction of motion by inertia transforms rectilinear motion into curvilinear (Fig. 2). The ball, having rolled off the inclined chute, continues to move in a straight line by inertia. If you put a magnet on the side, then under the action of the force of attraction to the magnet, the trajectory of the ball is curved.
No matter how hard you try, you cannot throw the cork ball so that it describes circles in the air, but by tying a thread to it, you can make the ball rotate in a circle around your hand. Experience (Fig. 3): a weight suspended from a thread passing through a glass tube pulls the thread. The force of tension on the thread causes centripetal acceleration, which characterizes the change in the linear velocity in the direction.
The moon revolves around the earth, held by gravity. The steel rope that would replace this force should have a diameter of about 600 km.But, despite such a huge force of gravity, the Moon does not fall to the Earth, because it has an initial velocity and, moreover, moves by inertia.
Knowing the distance from the Earth to the Moon and the number of revolutions of the Moon around the Earth, Newton determined the magnitude of the centripetal acceleration of the Moon.
It turned out the same number - 0.0027 m / s 2
Stop the action of the force of attraction of the Moon to the Earth - and it rushes in a straight line into the abyss of outer space. The ball will fly away tangentially (Fig. 3), if the thread that holds the ball while rotating around the circle breaks. In the device in Fig. 4, on a centrifugal machine, only the link (thread) holds the balls in a circular orbit. When the thread breaks, the balls run tangentially. With the eye it is difficult to catch their rectilinear movement when they are disconnected, but if we make such a drawing (Fig. 5), then it follows from it that the balls will move rectilinearly, tangentially to the circle.
Stop moving by inertia - and the Moon would fall to Earth. The fall would have lasted four days nineteen hours fifty-four minutes fifty-seven seconds, Newton calculated.
Using the formula for the law of universal gravitation, you can determine with what force the Earth attracts the moon: where G -gravitational constant, t 1 and m 2 are the masses of the Earth and the Moon, r is the distance between them. Substituting specific data in the formula, we get the value of the force with which the Earth attracts the moon and it is approximately 2 10 17 N
The law of universal gravitation applies to all bodies, which means that the sun also attracts the moon. Let's calculate with what force?
The mass of the Sun is 300,000 times the mass of the Earth, but the distance between the Sun and the Moon is 400 times greater than the distance between the Earth and the Moon. Therefore, in the formula, the numerator will increase 300,000 times, and the denominator - 400 2, or 160,000 times. The force of gravity will be almost twice as large.
But why doesn't the moon fall on the sun?
The moon falls on the sun in the same way as on the earth, that is, only enough to remain at approximately the same distance, revolving around the sun.
The Earth revolves around the Sun together with its satellite - the Moon, which means that the Moon revolves around the Sun.
The following question arises: the Moon does not fall to the Earth, because, having an initial velocity, it moves by inertia. But according to Newton's third law, the forces with which two bodies act on each other are equal in magnitude and oppositely directed. Therefore, with what force the Earth attracts the Moon to itself, with the same force the Moon attracts the Earth. Why doesn't the Earth fall on the Moon? Or does it also revolve around the moon?
The fact is that both the Moon and the Earth revolve around a common center of mass, or, to simplify, one might say, around a common center of gravity. Think back to the experience with balls and a centrifugal machine. The mass of one of the balls is twice the mass of the other. In order for the balls connected by a thread to remain in equilibrium with respect to the axis of rotation during rotation, their distance from the axis, or the center of rotation, must be inversely proportional to their masses. The point or center around which these balls revolve is called the center of mass of the two balls.
Newton's third law in the experiment with balls is not violated: the forces with which the balls pull each other towards the common center of mass are equal. In the Earth-Moon system, the common center of mass revolves around the Sun.
Is it possible the force with which the Earth attracts Lou well, called the weight of the moon?
No. We call the weight of a body the force caused by the Earth's gravity, with which the body presses on some support: a weighing pan, for example, or stretches the spring of a dynamometer. If you put a stand under the Moon (from the side facing the Earth), then the Moon will not press on it. The moon will not stretch the dynamometer spring, if they could hang it. The entire action of the force of attraction of the Moon by the Earth is expressed only in keeping the Moon in orbit, in imparting centripetal acceleration to it. It can be said about the Moon that in relation to the Earth it is weightless, just as objects in a spaceship-satellite are weightless, when the engine stops working and only the force of attraction to the Earth acts on the spacecraft, but this force cannot be called weight. All objects released by the astronauts from their hands (fountain pen, notebook) do not fall, but float freely inside the cabin. All the bodies on the Moon, in relation to the Moon, of course, are weighty and will fall on its surface if they are not supported by something, but in relation to the Earth these bodies will be weightless and cannot fall to the Earth.
Is there centrifugal force in to the Earth-Moon system, what does it act on?
In the Earth-Moon system, the forces of mutual attraction of the Earth and the Moon are equal and oppositely directed, namely to the center of mass. Both of these forces are centripetal. There is no centrifugal force here.
The distance from the Earth to the Moon is approximately 384,000 km.The ratio of the mass of the Moon to the mass of the Earth is 1/81. Consequently, the distances from the center of mass to the centers of the Moon and Earth will be inversely proportional to these numbers. Dividing 384,000 kmby 81, we get about 4 700 km.This means that the center of mass is at a distance of 4 700 kmfrom the center of the earth.
The radius of the Earth is about 6400 km.Consequently, the center of mass of the Earth-Moon system lies inside the globe. Therefore, if you do not pursue accuracy, we can talk about the revolution of the moon around the earth.
It is easier to fly from Earth to the Moon or from the Moon to Earth, because it is known that in order for a rocket to become an artificial satellite of the Earth, it must be told its initial velocity ≈ 8 km / sec... In order for the rocket to leave the Earth's sphere of gravity, the so-called second cosmic speed, equal to 11.2 km / sec.To launch rockets from the moon, you need a lower speed because the force of gravity on the moon is six times less than on Earth.
The bodies inside the rocket become weightless from the moment when the engines stop working and the rocket will fly freely in orbit around the Earth, while being in the Earth's gravitational field. During free flight around the Earth, both the satellite and all objects in it relative to the center of mass of the Earth move with the same centripetal acceleration and therefore are weightless.
How did the balls not tied by a thread move on a centrifugal machine: along a radius or tangentially to a circle? The answer depends on the choice of the frame of reference, i.e., relative to which reference body we will consider the motion of the balls. If the table surface is taken as the reference system, then the balls moved along tangents to the circles they describe. If we take the rotating device itself as a frame of reference, then the balls moved along a radius. Without specifying a reference frame, the question of motion has no meaning at all. To move means to move relative to other bodies, and we must definitely indicate which ones.
What is the moon around?
If we consider the motion relative to the Earth, then the Moon revolves around the Earth. If the Sun is taken as the reference body, then it is around the Sun.
Could Earth and Moon Collide? Their op the bits around the sun intersect, and not even once .
Of course not. Collision is possible only if the Moon's orbit relative to the Earth crossed the Earth. With the position of the Earth or the Moon at the point of intersection of the shown orbits (relative to the Sun), the distance between the Earth and the Moon is on average 380,000 km.To better understand this, let's draw the following. He depicted the Earth's orbit as an arc of a circle with a radius of 15 cm (the distance from the Earth to the Sun, as you know, is equal to 150,000,000 km).On an arc equal to a part of the circle (the monthly path of the Earth), he noted five points at equal distances, counting the extreme ones. These points will be the centers of the lunar orbits relative to the Earth in successive quarters of the month. The radius of the lunar orbits cannot be drawn on the same scale as the Earth's orbit, as it will be too small. To draw the lunar orbits, the selected scale must be increased by about ten times, then the radius of the lunar orbit will be about 4 mm.Thereafter indicated on each orbit the position of the moon, starting with a full moon, and connected the marked points with a smooth dashed line.
The main task was to split the reference bodies. In the experiment with a centrifugal machine, both reference bodies are simultaneously projected onto the plane of the table, so it is very difficult to focus on one of them. We have solved our problem as follows. A ruler made of thick paper (you can replace it with a strip of tin, plexiglass, etc.) will serve as a rod along which a cardboard circle resembling a ball slides. The circle is double, glued along the circumference, but slots are left on two diametrically opposite sides through which the ruler is threaded. Holes are made along the axis of the ruler. The reference bodies are a ruler and a sheet of blank paper, which we attached to a sheet of plywood with buttons so as not to spoil the table. Putting the ruler on the pin, like on an axis, they stuck the pin into the plywood (Fig. 6). When you turn the ruler to equal angles consecutive holes were on one straight line. But when the ruler turned, a cardboard circle slid along it, the successive positions of which had to be noted on paper. For this purpose, a hole was also made in the center of the circle.
At each turn of the ruler, the point of a pencil marked on the paper the position of the center of the circle. When the ruler passed through all the positions previously planned for it, the ruler was removed. Having connected the marks on the paper, we made sure that the center of the circle moved relative to the second reference body in a straight line, or rather along a tangent to the initial circle.
But while working on the device, I made some interesting discoveries. First, with uniform rotation of the rod (ruler), the ball (circle) moves along it not evenly, but accelerated. By inertia, the body must move evenly and rectilinearly - this is the law of nature. But did our ball move only by inertia, that is, freely? No! The rod pushed him and gave him acceleration. This will be clear to everyone if we refer to the drawing (Fig. 7). On a horizontal line (tangent) by points 0, 1, 2, 3, 4 the positions of the ball are marked if it were moving completely freely. The corresponding positions of the radii with the same numerical designations indicate that the ball is moving at an accelerated rate. The ball is accelerated by the elastic force of the rod. In addition, the friction between the ball and the rod resists movement. If we assume that the friction force is equal to the force that imparts acceleration to the ball, the motion of the ball along the rod should be uniform. As can be seen from Figure 8, the motion of the ball relative to the paper on the table is curvilinear. In drawing lessons, we were told that such a curve is called the "Archimedes spiral". On such a curve, the profile of the cams is drawn in some mechanisms when they want to turn a uniform rotational movement into a uniform translational movement. If you put two such curves together, the cam will get a heart-shaped shape. With uniform rotation of a part of this shape, the rod resting on it will perform a forward-reverse motion. I made a model of such a cam (Fig. 9) and a model of a mechanism for evenly winding threads on a spool (Fig. 10).
I did not make any discoveries while completing the assignment. But I learned a lot while making this diagram (Figure 11). It was necessary to correctly determine the position of the Moon in its phases, to think about the direction of movement of the Moon and the Earth in their orbits. There are inaccuracies in the drawing. I'll talk about them now. At the selected scale, the curvature of the lunar orbit is displayed incorrectly. It must be all the time concave with respect to the Sun, that is, the center of curvature must be inside the orbit. In addition, there are not 12 lunar months in a year, but more. But one twelfth of a circle is easy to construct, so I tentatively assumed that there are 12 lunar months in a year. And, finally, not the Earth itself revolves around the Sun, but the common center of mass of the Earth-Moon system.
Conclusion
One of striking examples achievements of science, one of the evidence of the unlimited cognizability of nature was the discovery of the planet Neptune by calculations - "at the tip of a pen."
Uranus, the planet following Saturn, which for many centuries was considered the most distant of the planets, was discovered by V. Herschel at the end of the 18th century. Uranus is hardly visible to the naked eye. By the 40s of the XIX century. accurate observations have shown that Uranus is barely noticeable deviating from the path that it should follow "in view of the perturbations of all known planets. Thus, the theory of motion of celestial bodies, so rigorous and accurate, was tested.
Le Verrier (in France) and Adam (in England) suggested that if perturbations from the known planets do not explain the deviation in the motion of Uranus, it means that the attraction of a still unknown body acts on it. They almost simultaneously calculated where behind Uranus there should be an unknown body, producing these deviations by its attraction. They calculated the orbit of the unknown planet, its mass and indicated the place in the sky where the unknown planet was supposed to be at this time. This planet was found in a telescope at the place indicated by them in 1846. It was named Neptune. Neptune is invisible to the naked eye. Thus, the disagreement between theory and practice, which seemed to undermine the authority of materialistic science, led to its triumph.
List of references:
1. M.I. Bludov - Conversations on Physics, part one, second edition, revised, Moscow "Education" 1972.
2. B.A. Vorontsov-Veliamov - Astronomy! Grade 1, 19th edition, Moscow "Enlightenment" 1991.
3. A.A. Leonovich - I know the world, Physics, Moscow AST 1998.
4. A.V. Peryshkin, E.M. Gutnik - Physics grade 9, Publishing House Bustard 1999.
5. Ya.I. Perelman - Entertaining physics, Book 2, Edition 19th, Publishing House "Science", Moscow 1976.
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One ancient Greek, allegedly Plutarch, uttered: they say, as soon as the Moon slows down, it will immediately fall to the Earth, like a stone released from a sling. This was said back when the stars were falling, not meteorites. Seventeen centuries later, Galileo, already armed not only with the art of reasonable generalizations, but also with a telescope, continued: The moon, they say, does not slow down because it moves by inertia, and obviously nothing prevents this movement. Said it suddenly and bluntly. Two hundred and three years later, Newton inserted himself: they say, dear ones, if the Moon moved only by inertia, it would move in a straight line, long ago disappearing into the abyss of the Universe; The Earth and the Moon are held close to each other by the force of mutual gravity, forcing the latter to move in a circle. Moreover, he said, gravity, being, most likely, the primary cause of any movement in the Universe, is capable of even accelerating the slightly slowed run of the Moon in certain parts of the elliptical (Keplerian) orbit ... gravitation. That's all. Therefore, it is inertia and gravity, forcing the moon to move in a closed orbit, and are the reasons that prevent the moon from falling to Earth. In short, if the gravitational mass of the Earth suddenly increases, then the Moon will only move away from it in its higher orbit. But ... The satellites of the planets cannot have any closed orbits - circular and elliptical. Now we will look at the joint "fall" of the Earth and the Moon on the Sun and make sure of this. So, the Earth and the Moon together "fall" in the gravitational space of the Sun for about 4 billion years. In this case, the speed of the Earth relative to the Sun is about 30 km / s, and the Moon's - 31. For 30 days, the Earth travels along its trajectory 77.8 million km (30 x 3600 x 24 x 30), and the Moon - 80.3. 80.3 - 77.8 \u003d 2.5 million km. The radius of the moon's orbit is approximately 400,000 km. Therefore, the circumference of the Moon's orbit is 400,000 x 2 x 3.14 \u003d 2.5 million km. In our reasoning alone, 2.5 million km is already the "curvature" of an almost straight trajectory of the Moon. A large-scale display of the trajectories of the Earth and the Moon may look like this: if there is 1 million km in one cell, then the path traversed by the Earth and the Moon in a month will not fit into the entire turn of the notebook into a cell, while the maximum distance of the trajectory of the Moon from the trajectory of the Earth in the phases of the full moon and new moon will be equal to only 2 millimeters. However, you can take a segment of an arbitrary length that represents the path of the Earth, and draw the movement of the Moon in a month. The movement of the Earth and the Moon occurs from right to left, that is, counterclockwise. If the Sun is somewhere at the bottom of the figure, then on the right side of the figure we will mark the Moon in the full moon phase with a dot. Let the Earth at this time be exactly under this point. In 15 days, the Moon will be in the new moon phase, that is, just in the middle of our segment and just under the Earth in the figure. On the left side of the figure, we again denote by dots the position of the Moon and the Earth in the full moon phase. The moon twice crosses the trajectory of the Earth in the so-called nodes during the month. The first node will be approximately 7.5 days from the full moon phase. From the Earth at this time, just half of the lunar disk is visible. This phase is called the first quarter, since the Moon by this time passes a quarter of its monthly path. The second time the Moon crosses the Earth's trajectory in the last quarter, that is, approximately 7.5 days from the new moon phase. Have you painted? Here's what's interesting: the Moon at the node of the first quarter is 400,000 km ahead of the Earth, and at the node of the last quarter - already 400,000 km behind it. It turns out that the Moon "along the upper crest of the wave" moves with acceleration, and "along the lower" - with deceleration; the path of the Moon from the node of the last quarter to the node of the first quarter is 800,000 km longer. Of course, the Moon in its motion along the "upper arc" does not accelerate spontaneously, it is the Earth with its gravitational mass that captures it and, as it were, throws it over itself. It is this property of moving planets - to capture and toss - and is used to accelerate space probes during the so-called gravity assist. If the probe crosses the path of the planet in front of it, then we have a gravitational maneuver with the probe slowing down. It's simple. The full moon phase repeats after 29 days, 12 hours and 44 minutes. This is the synodic period of the Moon's revolution. Theoretically, the Moon should travel through its orbit in 27 days, 7 hours and 43 minutes. This is the sidereal period of circulation. The "inconsistency" in two days in textbooks is explained by the movement of the Earth and the Moon in a month relative to the round Sun. We explained this by the absence of any orbit of the moon. So, Newton explained the "non-fall" of the Moon to the Earth by its temporary accelerations while moving in an elliptical orbit. We seem to have explained it even easier. And most importantly - more correctly. '' Victor Babintsev
The article tells about why the Moon does not fall on the Earth, the reasons for its movement around the Earth and some other aspects of the celestial mechanics of our solar system.
The beginning of the space age
The natural satellite of our planet has always attracted attention. In ancient times, the Moon was the subject of the cult of some religions, and with the invention of primitive telescopes, the first astronomers could not stop gazing at the majestic craters.
A little later, with the discovery in other areas of astronomy, it became clear that not only our planet, but also a number of others have such a celestial satellite. And Jupiter has 67 of them! But ours is the leader in size in the entire system. But why doesn't the moon fall to earth? What is the reason for its movement in the same orbit? We will talk about this.
Celestial Mechanics
To begin with, you need to understand what movement in orbit is and why it occurs. According to the definitionused by physicists and astronomers, an orbit is movement in another, significantly superior in mass, object. For a long time, it was believed that the orbits of planets and satellites have a circular shape as the most natural and perfect, but Kepler, after unsuccessful attempts to apply this theory to the motion of Mars, rejected it.
As you know from the physics course, any two objects experience mutual so-called gravity. The same forces are affecting our planet and the moon. But if they are attracted, then why does the Moon not fall to the Earth, as it would be most logical?
The thing is that the Earth does not stand still, but moves around the Sun in an ellipse, as if constantly "running away" from its satellite. And that, in turn, has an inertial speed, which is why it travels in an elliptical orbit again.
The simplest example that can explain this phenomenon is a ball on a rope. If you spin it, it will hold the object in one plane or another, and if you slow down, then it will not be enough and the ball will fall. The same forces act and the Earth drags it along, not allowing it to stand still, and the centrifugal force developed as a result of rotation holds it, preventing it from approaching a critical distance.
If an even simpler explanation is given to the question of why the Moon does not fall on the Earth, then the reason for this is the equal interaction of forces. Our planet attracts the satellite, forcing it to rotate, and the centrifugal force, as it were, repels.
The sun
Similar laws apply not only to our planet and satellite, all others obey them In general, gravity is very interesting topic... The movement of the planets around is often compared to the clockwork, it is so accurate and verified. And most importantly, it is extremely difficult to break it. Even if we remove several planets from it, the rest with a very high probability will be rearranged to new orbits, and collapse with a fall on the central star will not occur.
But if our star has such a colossal gravitational effect even on the most distant objects, then why does the Moon not fall on the Sun? Of course, the star is at a much farther distance than the Earth, but its mass, and hence gravity, is an order of magnitude higher.
The thing is that its satellite also moves in an orbit around the Sun, and the latter affects not separately on the Moon and the Earth, but on their common center of mass. And on the moon there is a double influence of gravity - the stars and planets, and after it the centrifugal force, which balances them. Otherwise, all satellites and other objects would have burned out in a hot light long ago. This is exactly the answer to frequent question about why the moon doesn't fall.
Movement of the sun
It is also worth mentioning the fact that the Sun is also moving! And along with it, our entire system, although we are used to thinking that outer space is stable and unchanging, with the exception of the orbits of the planets.
If you look more globally, within the framework of systems and their entire clusters, you can see that they also move along their trajectories. In this case, the Sun with its "satellites" revolves around the center of the galaxy. If we conditionally present this picture from above, it looks like a spiral with many branches, which are called galactic arms. In one of these arms, along with millions of other stars, our Sun is also moving.
The fall
But still, if you ask such a question and dream up? What conditions are needed under which the Moon will crash into the Earth or go on a journey to the Sun?
This can happen if the satellite stops rotating around the main object and the centrifugal force disappears, or if something changes its orbit and adds speed, for example, a collision with a meteorite.
Well, it will go to the star if purposefully somehow stop its movement around the Earth and give the initial acceleration to the star. But most likely, the Moon will simply gradually rise into a new curved orbit.
To summarize: the Moon does not fall on the Earth, because, in addition to the attraction of our planet, it is also affected by a centrifugal force, which, as it were, repels it. As a result, these two phenomena counterbalance each other, the satellite does not fly away and does not crash into the planet.
Relevance:
On April 12, our country recalls a grandiose event - a manned flight into space. In the lessons we also discussed the topic of space, drew pictures. And the teacher asked us to prepare interesting reports about space. Therefore, I chose this particular topic, since I myself am interested in it. And on the eve of this holiday "Cosmonautics Day" for us it is relevant, I think that you will be interested too.
My assumptions:
At home, I got the encyclopedia "Heavenly Bodies" and began to read. Then I asked myself, can the Moon fall on us? I replied that, probably, the moon will fall if it gets closer to the Earth. Or maybe something keeps it with the Earth, so it does not fall and does not fly away anywhere.
The purpose and objectives of my work:
I decided to study the literature in more detail, how the Moon was formed, how it affects the Earth, what connects it with the Earth, and why the Moon does not fly into space and does not fall on the Earth. And here's what I learned.
Introduction
In astronomy, a satellite is a body that revolves around a large body and is held by the force of its attraction. The Moon is the Earth's satellite. Earth is a satellite of the Sun. The moon is a solid, cold, spherical celestial body, which is 4 times smaller than the Earth.
The moon is the closest celestial body to the Earth. If it were possible, the tourist would walk to the moon for 40 years
The Earth-Moon system is unique in Solar systemsince no planet has such a large satellite. The moon is the only satellite of the earth.
It is visible to the naked eye better than any planet through a telescope. Our companion conceals many mysteries.
The moon is so far the only cosmic body that man has visited. The Moon revolves around the Earth in the same way as the Earth revolves around the Sun (see Fig. 1).
The distance between the centers of the Moon and the Earth is approximately 384467 km.
What does the moon look like?
The moon is not at all like the earth. There is no air, no water, no life. The concentration of gases near the lunar surface is equivalent to a deep vacuum. Due to the lack of atmosphere, its gloomy dusty expanses heat up during the day to + 120 ° С and freeze at night or just in the shade up to - 160 ° С. The sky on the moon is always black, even during the day. The huge disk of the Earth looks from the Moon more than 3.5 times than the Moon from the Earth, and hangs in the sky almost motionless (see Fig. 2).
The entire surface of the moon is pitted with funnels, which are called craters. You can see them by looking closely at the moon on a clear night. Some craters are so big that a huge city could fit inside. The main variants of crater formation are two - volcanic and meteoric.
The lunar surface can be divided into two types: very old mountainous terrain (lunar continent) and relatively smooth and younger lunar seas.
Lunar seas, which make up approximately 16% of the entire surface of the Moon, are huge craters created by collisions with celestial bodies that were later flooded with liquid lava. The lunar seas were named: Sea of \u200b\u200bCrises, Sea of \u200b\u200bAbundance, Sea of \u200b\u200bTranquility, Sea of \u200b\u200bRains, Sea of \u200b\u200bClouds, Sea of \u200b\u200bMoscow and others.
Compared to Earth, the Moon is very small. The radius of the moon is 1738 km, the volume of the moon is 2% of the volume of the earth, and the area is about 7.5%
How was the moon formed?
The moon and the earth are almost the same age. Here is one of the versions of the formation of the moon.
1. Soon after the formation of the Earth, a huge celestial body crashed into it.
2. From the impact it shattered into many fragments.
3. Under the influence of gravity (attraction) of the Earth, the fragments began to revolve around it.
4. Over time, the fragments came together, and from them the moon was formed.
Moon phases
The moon changes its appearance every day. First a narrow sickle, then the moon gets fat and after a few days it becomes round. Some more days full moon gradually becomes smaller and smaller and again becomes like a sickle. The crescent moon is often referred to as the month. If the sickle is turned with a bulge to the left, like the letter "C", then they say that the moon is "aging". In 14 days and 19 hours after the full moon, the old month will disappear completely. The moon is not visible. This phase of the moon is called "new moon". Then gradually the Moon from a narrow crescent, turned to the right, turns back into a full moon.
For the moon to “grow” again, the same period of time is required: 14 days and 19 hours. Changing the appearance of the moon, i.e. the change in lunar phases, from full moon to full moon, occurs every four weeks, more precisely in 29 and a half days. This is the lunar month. It served as the basis for the compilation of the lunar calendar. During the full moon, the Moon is turned towards the Earth with the illuminated side, and during the new moon - with the unlit side. Turning around the Earth, the moon turns to it either with a completely illuminated surface, sometimes with a partially illuminated surface, sometimes with a dark one. That is why the appearance of the moon is constantly changing during the month.
Ebb and flow
The gravitational forces between the Earth and the Moon have some interesting effects. The most famous of these is the ebb and flow of the sea. The difference in high and low tide levels in open areas of the ocean is small and amounts to 30–40 cm. However, near the coast, due to the onslaught of the tidal wave on the solid bottom, the tidal wave increases in height in the same way as ordinary wind waves of the surf.
Taking into account the direction of rotation of the Moon around the Earth, it is possible to form a picture of the following of a tidal wave in the ocean. The maximum amplitude of the tidal wave on Earth is observed in the Bay of Fundy in Canada and is 18 meters.
Moon exploration
The moon has attracted people's attention since ancient times. The invention of telescopes made it possible to distinguish between the finer details of the relief (surface shape) of the Moon. One of the first lunar maps was compiled by Giovanni Riccioli in 1651, he also gave names to large dark areas, calling them “seas”, which we still use today. In 1881 Jules Janssen compiled a detailed Photographic Atlas of the Moon.
Since the beginning of the space age, the amount of our knowledge about the Moon has increased significantly. The Soviet spacecraft Luna-2 visited the Moon for the first time on September 13, 1959.
For the first time it was possible to look at the far side of the Moon in 1959, when the Soviet station Luna-3 flew over it and photographed the part of its surface invisible from Earth.
The American manned mission to the moon was called the Apollo.
The first landing took place on July 20, 1969, and the first person to set foot on the lunar surface was American Neil Armstrong. Six expeditions have visited the moon, but the last time was back in 1972, since the expeditions are very expensive. Each time two people landed on it, who spent up to three days on the moon. New expeditions are currently being prepared.
Why doesn't the moon fall to earth?
The moon would instantly fall to Earth if it were stationary. But the Moon does not stand still, it revolves around the Earth.
When we throw an object, such as a tennis ball, gravity pulls it towards the center of the earth. Even a tennis ball thrown at high speed will still fall to the ground, but the picture changes if the object is much further away and moves much faster.
My experience:
I asked this question to my dad and he explained it to me with a simple example. We tied an ordinary eraser to a string. Imagine that you are the Earth and the eraser is the moon, and start spinning it. The eraser on the thread will pull out of your hand, but the thread will not let it go. The moon is so far away and moving so fast that it never falls down in one direction. Even falling constantly, the moon will never fall to earth. Instead, it moves around the earth in a constant path.
If we rotate the eraser very hard, the thread will break, and if we rotate it slowly, the eraser will fall.
We conclude: if the moon moved even faster, then it would overcome the gravity of the earth and flew into space; if the moon moved slower, the force of gravity would pull it to the earth. This precise balance of the speed of gravity creates what we call an orbit, where the smaller celestial body constantly revolves around the larger one.
The force that prevents the Moon from “running away” as it rotates is the Earth's gravity. And the force that prevents the Moon from falling to the Earth is the centrifugal force that occurs when the Moon rotates around the Earth.
Orbiting the Earth, the Moon moves in orbit at a speed of 1 km / sec, that is, slow enough not to leave its orbit and “fly away” into space, but also fast enough not to fall to Earth.
By the way...
You will be surprised, but in fact the Moon ... is moving away from the Earth at a rate of 3-4 cm per year! The movement of the moon around the earth can be thought of as a slowly unwinding spiral. The reason for this trajectory of the Moon is the Sun, which attracts the Moon 2 times more than the Earth.
Why, then, does the moon not fall on the sun? And because the Moon, together with the Earth, revolves, in turn, around the Sun, and the attractive action of the Sun is completely spent on constantly transferring both of these bodies from a straight path into a curved orbit.
- The Moon itself does not shine, it only reflects the sunlight falling on it;
- The moon turns around its axis in 27 Earth days; during the same time, it makes one revolution around the Earth;
- The moon, revolving around the earth, always faces us with one side, its reverse side remains invisible to us;
- The moon, moving in its orbit, is gradually moving away from the Earth by about 4 cm per year.
- The force of gravity on the Moon is 6 times less than on Earth.
Therefore, it is much easier for a rocket to take off from the Moon than from Earth.
It is possible that soon on distant interplanetary flights spaceships will be sent not from the Earth, but from the Moon.
At the beginning of this century, China announced its readiness to explore the moon, as well as to build several habitable lunar bases there. After this statement space organizations leading countries, in particular the United States (NASA) and ESA (European Space Agency) again deployed their space programs.
What will come of this?
Let's see in 2020. It was for this year that G. Bush planned the landing of people on the moon. This date is ahead of China by a whole ten years, since in their space program it was said that the creation of inhabited lunar bases and the landing of people on them would take place only in 2030.
The moon is the most studied celestial body, but for humans it still harbors many mysteries: perhaps it is the base of extraterrestrial civilizations, perhaps life on Earth would be completely different if there was no moon, perhaps in the future a person will settle on the moon ...
Conclusions:
So, we found out that the moon is natural satellite Earth, it revolves around our planet and, together with the Earth, moves in an orbit around the Sun;
- the question of the origin of the moon is still controversial;
- changes in the shape of the moon are called phases. They exist only for us
One of my assumptions turned out to be correct, the Moon is really held by something, and this is the Earth's gravity and centrifugal force.
And my other assumption that the moon will fall if it approaches the Earth is not entirely correct. The Moon will fall to the Earth when the Moon stops rotating, is motionless, then the centrifugal force will not work.
Studying encyclopedias and the Internet, I learned a lot of new and interesting things. I will definitely share these discoveries with my classmates in the world around me class.
We managed to solve some of the riddles of the Moon, but this did not make it less interesting and attractive!
References:
1. “Space. Supernova Atlas of the Universe ”, M.,” Eksmo ”, 2006.
2. New school encyclopedia "Celestial bodies", M., "Rosmen", 2005
3. "Why Much" Children's Encyclopedia, M., "Rosmen", 2005.
4. “What is it? Who it?" children's encyclopedia, M., "Pedagogy -
Press "1995
5. Internet - reference books, pictures about space.
Completed: student of grade 3B
Khaliullin Ildar
Leader: Sakaeva G.Ch.
MOU Secondary School No. 79, Ufa