Double planet Earth - Moon
The luminary of the night, the affectionate goddess Selene, as the ancient Greeks called her, the Moon invariably accompanies the Earth in its run around the Sun.
The Moon is the celestial body closest to us. The distance to it is only 384 thousand kilometers, according to on a cosmic scale- just a stone's throw away!
Compared to the Earth, the Moon is small. Its diameter is 3,476 kilometers, slightly more than a quarter of the Earth's, and its surface is equal to the area of Africa and Australia combined. The mass of the Moon is 81.3 times less than the mass of the Earth. And yet, in comparison with its size, the Earth has the largest satellite in the family of planets solar system.
Triton, Neptune's moon, is 770 times lighter than its planet; Titan, the most large satellite Saturn, 4030 times lighter than Saturn; largest moon Jupiter, Ganymede, is 12,200 times lighter than the planet. There is nothing to say about other satellites: their masses are tens and hundreds of thousands of times less than the masses of the planets around which they orbit. And that is why many astronomers call the Earth-Moon system a double planet.
In fact, the first people to view the Earth from Venus would see double star. One of them would appear very bright, and the other, located nearby, although much fainter, would be clearly visible.
The Earth, accompanied by the Moon, moves around the Sun.
How did the double planet Earth - Moon come into being? There are two assumptions on this score, or, to put it scientifically, two hypotheses.
The first one is this. Several billion years ago, both the Earth and the Moon, independently of one another, were formed from clumps of cosmic matter in various areas world space. And then the Moon, in its celestial wanderings, inadvertently came too close to the Earth, and our planet, taking advantage of its greater mass, captured the Moon according to the laws of gravity and made it a satellite.
According to the second hypothesis, both the Earth and the Moon were formed from one clump of matter. And at the beginning of their existence, these two celestial bodies were much closer friend to friend. But gradually the Moon moved away from the Earth and took its present position. The younger sister continues to move away from the older one, but many millions of years will pass before this becomes noticeable.
It is difficult to say which of the two assumptions is more correct. Scientists will still have to work a lot to finally resolve the question of the origin of the Moon.
Solar system (without observing the scales of the Sun and planets and the distances between them).
Lunar eclipses
Of all celestial phenomena People have long been most afraid of lunar and solar eclipses.
On clear sky The moon is shining brightly. Not a cloud around her. And suddenly a dark shadow approaches the shining surface of the Moon from nowhere. More, more... Here it is most of lunar surface disappeared, and then everything else disappears. True, it cannot be said that the Moon is not in the sky: it is still visible in the form of a dark purple disk.
A lunar eclipse is explained by the fact that the Moon falls into earth's shadow. If the shadow that the Earth casts from itself covers the Moon entirely, then the so-called full eclipse. And if it does not cover the entire Moon, then a partial lunar eclipse occurs.
A partial eclipse does not make as strong an impression on observers as a total eclipse. After all, the crescent moon is a familiar sight for us.
In the old days, people thought that the Moon was devoured by a terrible monster - a dragon - during an eclipse. Some peoples believed in this so much that they tried to drive away the dragon with the sound of rattles and the roar of drums. And when the Moon appeared in the sky again, people rejoiced: it means that the dragon, frightened by the noise, abandoned its victim.
And in Rus' in the old days, lunar eclipses were considered formidable harbingers of troubles.
In 1248, the chronicler wrote: “There was a sign on the moon: it was all bloody and died... And in the same summer, King Batu moved the army...”
Our ancestors thought that a lunar eclipse predicted the invasion of the Tatar Khan Batu.
How to tell if the crescent moon is growing or shrinking.
In 1471, it was written in the chronicle: “The midnight was unclear, and like blood on the moon and darkness there was a considerable time and again it gradually cleared up..”
Each eclipse was recorded in history as an important event in the life of the people. For a lunar eclipse to occur, the Sun, Earth and Moon must be in one straight line and the Earth must be between the Sun and the Moon. This position of these three luminaries in celestial space is repeated at certain intervals.
Astronomers in ancient times noticed that every 18 years 11 days 8 hours lunar eclipses are repeated in the same order; It is enough to write down the order of eclipses, and you can confidently predict eclipses for the future.
I have already said that in ancient times priests were mostly astronomers. Having learned to predict eclipses, the priests turned their knowledge to the benefit of religion. They deceived the people, assuring them that the gods themselves were telling them about the approaching eclipse. This is how they supported religious superstitions.
Now the art of predicting eclipses has been perfected high precision, and there is a schedule lunar eclipses for many years to come.
Why do lunar eclipses occur?
Science takes space by storm
Until recently, the possibility of making interplanetary travel seemed so far away... But in space age technology moves quickly, and what seemed impossible yesterday becomes feasible today.
The era of the greats geographical discoveries also did not come immediately. Before setting off in search of distant continents, people discovered coastal islands and, sailing to them, improved their skills.
The same is true with the conquest of space. Among the expanses of the solar system, the Moon is the closest space object, and the path there has already been paved.
Traveling to the Moon will be an excellent school for space flights. But even though the distance between the Earth and the Moon is small (on a cosmic scale), the space separating them has many of the properties of the Greater Space.
What if we flew to the moon - in our imagination, of course? What should we use for this? Maybe by plane?
The 384 thousand kilometers separating the Moon from the Earth is not such a long distance. We have planes that fly 2,500 kilometers per hour. This is TU-144. For such an aircraft, 384 thousand kilometers are simply nothing.
Let's do the calculation. Let's divide 384 thousand kilometers by 2500 kilometers. We get about 154 hours of flight, approximately 6.4 days. We need to stock up on enough provisions, water, and most importantly, more fuel for the engine so that there is enough for the return trip.
Fortunately, a large, roomy plane was found. Everything you need has been loaded. We sat down and drove off. How nice it is to be an explorer of world space!
The plane goes up steeply. Here the altitude indicator arrow shows 5, 10, 15 kilometers... Earthly objects are becoming smaller and smaller: rivers seem like thin winding threads, forests - dark spots.
But what is it? Our plane stopped gaining altitude.
What's the matter? - we shout to the pilot.
The air is too thin,” the pilot replies. - The engine can no longer operate normally.
And you're right, of course. You also know how to fly to the moon: on a rocket! Yes, you can only reach the Moon in a rocket, because only a rocket can break the shackles of gravity.
The shackles of gravity... What does this mean?
You push off the floor and jump, but in a split second you're on the floor. The athlete throws a hammer; Having described an arc of several tens of meters, the hammer falls onto the stadium. The anti-aircraft gunners fired at the enemy plane; the shell rose seven to eight kilometers, and its fragments flew back... All bodies of nature are attracted to the Earth.
phases relative to the rays of the Sun. The impression is as if the rays of the Sun are bent before reaching the Moon.
The answer lies in the following. The ray going from the Sun to the Moon is actually perpendicular to the line connecting the ends of the month
Rice. 36. In what position relative to the Sun do we see the Moon in different phases.
tsa, and in space it is a straight line. But our eye draws not this straight line in the sky, but its projection onto the concave vault of the sky, that is, a curved line. This is why it seems to us that the Moon is “hung incorrectly” in the sky. The artist must study these features and be able to transfer them to the canvas.
Double planet
A double planet is the Earth and the Moon. They have the right to this name because our satellite stands out sharply among the satellites of other planets due to its significant size and mass in relation to its central planet. There are satellites in the solar system that are absolutely larger and heavier, but compared to their own central planet they are much smaller than our Moon in relation to the Earth. In fact, the diameter of our Moon is more than a quarter of the Earth’s, and the diameter relative to the largest satellite of other planets is only a 10th of the diameter of its planet (Triton is a satellite of Neptune). Further, the mass of the Moon is 1/81 the mass of the Earth; Meanwhile, the heaviest of the satellites that exists in the solar system, the III satellite of Jupiter, is less than 10,000th of the mass of its central planet.
What fraction of the mass of the central planet is the mass large satellites, shows the sign on page 50.
You can see from this comparison that our Moon, in terms of its mass, makes up the largest share of its central planet.
The third thing that gives the Earth-Moon system the right to claim the name “double planet” is the close proximity of both celestial bodies. Many satellites of other planets circle at much greater distances: some satellites of Jupiter (for example, the ninth, Fig. 37 ) circle 65 times further.
In connection with this is the curious fact that the path described by the Moon around the Sun differs very little from the path of the Earth. This will seem incredible if you remember that the Moon moves around the Earth at a distance of almost 400,000 km. Let us not forget, however, that for now
The Moon makes one revolution around the Earth, the Earth itself manages to move along with it approximately the 13th part of its annual path, i.e.
Her companion | Weight (in fractions |
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mass of the planet) |
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Rice. 37. The Earth-Moon system compared with the Jupiter system. (The dimensions of the celestial bodies themselves are not shown to scale.)
70,000,000 km. Imagine the circular path of the Moon - 2,500,000 km - stretched along a distance 30 times greater. What will remain of its circular shape? Nothing. That is why the path of the Moon near the Sun almost merges with the Earth’s orbit, deviating from it only by 13 barely noticeable protrusions. It can be proven with a simple calculation (which we will not burden the exposition here) that the path of the Moon is everywhere facing the Sun with its concavity. Roughly speaking, it looks like a thirteen-sided triangle with softly rounded corners.
In Fig. 38 you see an accurate depiction of the paths of the Earth and Moon over the course of one month. The dotted line is the path of the Earth, the solid line is the path of the Moon. They are so close to each other that to depict them separately we had to take a very large drawing scale: diameter earth's orbit here it is equal to ½ m. If we take 10 cm for it, then the greatest distance in the drawing between both paths would be less than the thickness of the lines representing them. Looking at this drawing, you are clearly convinced that the Earth and the Moon move around the Sun almost along the same path and that the name “double planet” was assigned to them by astronomers quite rightly1).
So, for an observer placed on the Sun, the path of the Moon would appear to be a slightly wavy line, almost coinciding with the orbit of the Earth. This does not at all contradict the fact that in relation to the Earth the Moon moves along a small ellipse.
1) Carefully examining the drawing, you can notice that the movement of the Moon is not depicted as strictly uniform. This is actually true. The Moon moves around the Earth in an ellipse, the focus of which is the Earth, and therefore, according to Kepler’s second law, it runs faster in areas close to the Earth than in areas farther away. Eccentricity lunar orbit Quite large: 0.055.
The reason, of course, is that, looking from the Earth, we do not notice the portable movement of the Moon along with the Earth in the Earth’s orbit, since we ourselves participate in it.
Why doesn't the Moon fall on the Sun?
The question may seem naive. Why on earth would the Moon fall on the Sun? After all, the Earth attracts her more strongly distant sun and, naturally, makes it revolve around itself.
Readers who think this way will be surprised to learn that the opposite is true: the Moon is more strongly attracted by the Sun, not by the Earth!
The calculation shows that this is so. Let's compare the forces that attract the Moon: the force of the Sun and the force of the Earth. Both forces depend on two circumstances: on the magnitude of the attractive mass and on the distance of this mass from the Moon. Mass of the Sun more mass Earth 330,000 times; the Sun would attract the Moon just as many times more than the Earth if the distance to the Moon were the same in both cases. But the Sun is about 400 times farther from the Moon than the Earth. The force of attraction decreases in proportion to the square of the distance; therefore, the attraction of the Sun must be reduced by 4002, i.e. 160,000 times. This means that solar gravity is 330,000 times stronger than the earth’s, i.e.
Rice. 38. Monthly path of Lupa ( solid line) and the Earth (dotted line) around the Sun.
more than two times.
So, the Moon is attracted by the Sun twice as much as by the Earth. Why then, in fact, is the Moon not
collapsing into the sun? Why does the Earth still force the Moon to revolve around it, and does not the action of the Sun take over?
The Moon does not fall on the Sun for the same reason that the Earth does not fall on it; The Moon revolves around the Sun together with the Earth, and the attractive effect of the Sun is spent without a trace in constantly transferring both of these bodies from straight path into a curved orbit, i.e. turn straight motion into a curvilinear one. Just take a look at Fig. 38 to verify what was said.
Some readers may still have some doubts. How does this come out anyway? The Earth pulls the Moon towards itself, the Sun pulls the Moon with greater force, and the Moon, instead of falling on the Sun, circles around the Earth? It would indeed be strange if the Sun attracted only the Moon. But it attracts the Moon together with the Earth, the entire “double planet”, and, so to speak, does not interfere with internal relations members of this pair with each other. Strictly speaking, the common center of gravity of the Earth-Moon system is attracted to the Sun; This center (called the “barycenter”) revolves around the Sun under the influence of solar gravity. It is located at a distance of ⅔ of the Earth's radius from the center of the Earth towards the Moon. The Moon and the center of the Earth revolve around the barycenter, completing one revolution every month.
Visible and invisible sides of the Moon
Among the effects delivered by a stereoscope, nothing is as striking as the view of the Moon. Here you see with your own eyes that the Moon is really spherical, whereas in the real sky it seems flat, like
tea tray. | |
But how difficult is it to get something like this? | |
stereoscopic photograph of our | |
satellite, many don’t even suspect. | |
To make it you have to be good | |
familiar with the characteristics of capricious | |
movements of the night luminary. | |
The fact is that the Moon goes around the Earth | |
so that it is addressed to her all the time alone and | |
the same side. | |
As the Moon circles the Earth, it rotates | Rice. 39. How the Moon moves around |
at the same time and around its axis, and |
|
both movements end at the same time | Earth in its orbit. (Details - |
same period of time. | sti in the text.) |
In Fig. 39 you see an ellipse that should clearly depict the orbit of the Moon. The drawing deliberately enhances the elongation of the lunar ellipse; in fact, the eccentricity of the lunar orbit is 0.055 or 1/18. It is impossible to accurately represent the lunar orbit in a small drawing so that the eye can distinguish it from a circle: with the semi-major axis measuring even a whole meter, the semi-minor axis would be shorter than it by only 1 mm; The earth would be only 5.5 cm away from the center. To make it easier to understand the further explanation, a more elongated ellipse is drawn in the figure.
So, imagine that the ellipse in Fig. 39 is the path of the Moon around the Earth. The earth is placed at point O - at one of the foci of the ellipse. Kepler's laws apply not only to the movements of planets around the Sun, but also to the movements of satellites around the central planets, in particular to the formation
to the veneration of the moon. According to Kepler's second law, in a quarter of a month the Moon travels such a path AE that the area OABCDE is equal to ¼ the area of the ellipse, i.e. the area MABCD (the equality of the areas OAE and MAD in our drawing is confirmed by the approximate equality of the areas MOQ and EQD). So, in a quarter of a month the Moon travels from A to E. The rotation of the Moon, like the rotation of planets in general, in contrast to their revolution around the Sun, occurs evenly: in ¼ month it rotates exactly 90°. Therefore, when the Moon is in E, the radius of the Moon, facing the Earth at point A, will describe an arc of 90°, and will be directed not to point M, but to some other point, to the left of M, not far from another focus P of the lunar orbit. Because the Moon slightly turns its face away from the earthly observer, he will be able to see from right side a narrow strip of its previously invisible half. At point F, the Moon shows the earthly observer a narrower strip of its usual invisible side, because angle OFP is less than angle OEP. At point G - at the “apogee” of the orbit - the Moon occupies the same position in relation to the Earth as at “perigee” A. With its further movement, the Moon turns away from the Earth already at the opposite side, showing our planet another strip of its invisible side: this strip first expands, then narrows, and at point A the Moon takes its previous position.
We are convinced that, due to the elliptical shape of the lunar path, our satellite does not face the Earth with exactly the same half. The Moon invariably faces the same side not to the Earth, but to another focus of its orbit. For us, it sways around the middle position like a scale; hence the astronomical name for this rocking: “libration” - from Latin word"libra" meaning "scales". The amount of libration at each point is measured by the corresponding angle; for example, at point E the libration is equal to the angle OEP. Largest value libration 7°53", i.e. almost 8°.
It is interesting to watch how the libration angle increases and decreases as the Moon moves along its orbit. Let us place the tip of a compass at D and describe an arc passing through the foci O and P. It will intersect the orbit at points B and F. Angles OBP and OFP as inscribed are equal to half the central angle ODP. From this we conclude that when the Moon moves from A to D, the libration grows quickly at first, at point B it reaches half the maximum, then continues to increase slowly; On the way from D to F, libration decreases first slowly, then quickly. In the second half of the ellipse, libration changes its value at the same rate, but at reverse side. (The amount of libration at each point in the orbit is approximately proportional to the distance of the Moon from the major axis of the ellipse.)
That wobble of the Moon, which we have just examined, is called libration in longitude. Our satellite is also subject to another libration - in latitude. The plane of the lunar orbit is inclined to the plane of the equator
Moon at 6½°. Therefore, we see the Moon from the Earth in some cases a little from the south, in others from the north, looking a little into the “invisible” half of the Moon through its poles. This libration in latitude reaches 6½°.
Let us now explain how the astronomer-photographer uses the described slight swaying of the Moon around its middle position in order to obtain stereoscopic photographs of it. The reader probably guesses that for this it is necessary to lie in wait for two such positions of the Moon, in which in one it would be rotated relative to the other at a sufficient angle1). At points A and B, B and C, C and D, etc. The Moon occupies such different positions relative to the Earth that stereoscopic photographs are possible. But here we are faced with a new difficulty: in these positions the difference in the age of the Moon, 2 days, is too great, so that the strip of the lunar surface near the circle of illumination in one picture is already coming out of the shadow. This is unacceptable for stereoscopic images (the strip will shine like silver). Arises difficult task: to lie in wait for identical phases of the Moon, which differ in the amount of libration (in longitude) so that the circle of illumination passes over the same parts of the lunar surface. But this is not enough: in both positions there must also be equal librations in latitude.
You now see how difficult it is to get good stereo photographs of the Moon, and you will not be surprised to learn that often one photograph of a stereoscopic pair is taken several years later than the other.
Our reader is unlikely to take lunar stereo photographs. The method of obtaining them is explained here, of course, not with practical purpose, but only for the sake of it to consider the features lunar movement, giving astronomers the opportunity to see a small strip of the usually inaccessible side of our satellite. Thanks to both lunar librations, we see, in general, not half of the entire lunar surface, but 59% of it. 41% remains completely inaccessible to our vision. No one knows how this part of the lunar surface is structured; one can only guess that it does not differ significantly from the visible one. Ingenious attempts were made, by continuing back parts of the lunar ridges and light stripes emerging from the invisible part of the Moon onto the visible one, to sketch out some fortune-telling details of the half inaccessible to us. It is not yet possible to verify such guesses. We say “yet” not without reason: methods have long been developed to fly around the Moon on a special aircraft, which can overcome the gravity of the earth and move in interplanetary space (see my book “Interplanetary Travel”). The implementation of this bold undertaking is now not so far away. So far, one thing is known: the often expressed idea about the existence of an atmosphere and water on this
1) To obtain stereoscopic images, a rotation of the Moon by 1° is sufficient. (For more on this, see my Fun Physics.)
Lesson 16. Earth and Moon - double planet
Lesson Objectives
Personal : organize independent cognitive activity, express confidence in the possibility of knowing the world around us, in the unity of methods for studying the characteristics of the Earth and other planets.
Metasubject : provide evidence for considering the Earth and the Moon as a double planet, justify own opinion regarding the prospects for lunar exploration.
Subject : characterize the nature of the Earth; list the main physical conditions on the surface of the Moon; explain the differences between the two types of lunar surface (seas and continents); explain the processes of formation of the lunar surface and its relief; list the results of research carried out by automated vehicles and astronauts; characterize internal structure Moons, chemical composition of lunar rocks.
Main material
Determination of the main criteria for characterizing and comparing planets. Characteristics of the Earth according to the selected criteria. Characteristics of the Moon according to the selected criteria. Comparative characteristics of the atmosphere of the Moon and the Earth and the astrophysical and geological consequences of the difference. Comparative characteristics of the relief of the planets. Comparative characteristics of the chemical composition of the planets. Justification of the Earth-Moon system as a unique double planet in the Solar System.
Equipment: media projector, screen, internet,Web-services (Online planetarium, online telescope, Astronomy for children),texts containing information about the planets
DURING THE CLASSES
I. Updating knowledge
– Hello guys! Sit down! Today we will continue to study the knowledge of the sky. Now let’s check how you have mastered the material from previous classes.
II. Checking homework
Marathon across the starry sky.
How many stars are there in the sky?(6000), how much do we see? (3000)
How many constellations-88 (72 visible in our country)
What is the upper culmination of a luminary called??(the phenomenon of a luminary crossing the celestial meridian)
What is the ecliptic?(circle celestial sphere, according to which it occurs annual movement Sun)
Name the zodiac constellations.
What is the name of the 13th constellation (Ophiuchus)
Tell us about this constellation (homework)
III. Explanation of the new theoretical material
Staging educational problem
1. Why in his book “Secrets of the Birth of Stars and Planets” A. N. Tomilin calls the considered hypothesis of O. Yu. Schmidt about the origin of the bodies of the Solar System “capture theory”?
2. Describe the stages of formation of the Solar system, according to the hypothesis of O. Yu. Schmidt. What are the structural features of our planetary system can this hypothesis explain?
3. In the book “Secrets of the Birth of Stars and Planets” A. N. Tomilin writes:“The problem of gravitational acceleration of a spacecraft is the closest theoretical relative of the problems that are solved by capture theory" .
Explain this statement .
Work organization students in two areas: nature research
Earth and study of the nature of the Moon.
General discussion plan (list of criteria) by which any planet in the solar system should be analyzed.
Summary of the discussion.
1. Features of the structure of shells (atmosphere, hydrosphere, lithosphere).
2. physical characteristics planets (surface temperature, mass, radius, length of day, sidereal period).
3. Characteristics of the planet's relief.
4. Chemical composition of the planet's surface.
5. Distinctive features.
6. Peculiarities of planetary exploration by unmanned spacecraft/astronauts
(for the Moon).
Completing the task using the Astronomy for Children website
Teacher. I suggest dividing into 2 groups. And so, there are 2 groups of you. I propose to leave the distribution of planets to Lady Luck.
- Auction of planets : in front of you are encrypted planets in the form of questions. Choose one of them and you will find out which planet Lady Luck provided for study. Texts containing information about the planets are distributed.
Group 1. Describe the Earth as one of the planets in the solar system using the plan provided.
Group 2. Describe the Moon, the planetary body of the Solar System closest to Earth.
The result of the work : discussion of these characteristics of the Earth and the Moon, but not separately, but in comparison according to each of the first four criteria. During the discussion, students take notes on characteristics. At comparative characteristics The following recordings were made of the Earth and Moon.
1. Nsignificant gas envelope The moon has virtually no effect on the properties of the cislunar space - there is no protection against small particles falling onto the surface particulate matter substances.
2. Compared to the terrestrial periods of the day, dawn and sunset are absent on the Moon due to the absence of an atmosphere.
3. The use of concepts related to surface relief (“crater”, “sea”, “continent”, etc.) for the Moon has its own meaning and is determined more by historical factors. So, unlike lunar craters, on Earth volcanic craters are also called this way, despite their different structure and the reason that caused their appearance.
Working with the lunar map and earth's surface for both hemispheres.
(independent observations of the Moon usingWeb- online telescope service.
4 The characteristic that brings the Earth and the Moon closer together is their similarity in chemical composition. Their quantitative ratio and the presence of compounds, the formation of which is possible only in the presence of water, allows us to compare the two celestial bodies.
Prove by calculations the characteristics of the relationships of distinctive features :(UsageWebplanetarium service online.link.
http://onlinevsem.ru/obuchenie/planetarij-onlajn.)
Conclusion.
- planetary masses : using reference data, you can find that for the Earth and the Moon in the Solar System it is maximum and amounts to 1/81 (for example, for Neptune and Triton this ratio is 10 times less and is about 1/800);
- sizes of celestial bodies : Reference data allows students to determine that the radius of the Earth is less than 4 times the radius of the Moon (for example, the radius of Neptune is 10 times the radius of Triton);
- distances between a planet and its satellite : According to the reference data, students determine that this distance is only 384,400 km.
III Reinforcing the material learned
test
Option I :
1.What explains the absence of an atmosphere on the Moon?
A. 6 times less acceleration than on Earth free fall.
B. The acceleration of free fall is 6 times greater than on Earth.
B. 1.6 times less than on Earth, the acceleration of free fall.
2. What is the structure and physical properties upper layer of the lunar surface?
A. Porous structure.
B. The structure is porous, the strength is low, in a vacuum the particles that make up upper layer, stick together.
B. Continental type surface.
3. Is it possible to observe meteors on the Moon?
A. Yes, due to the lack of atmosphere.
B. No, due to the lack of atmosphere.
Q. Yes, this phenomenon is observed on all bodies of the Solar System.
4. How many times faster does the Moon move across the sky than the Sun?
A. The Sun and Moon move across the sky in the opposite direction daily rotation sky. During the day the Sun travels approximately 1 O , and the Moon is 13 O . Therefore, the Moon moves across the sky 13 times faster than the Sun.
B. The Sun and Moon move across the sky in the opposite direction to the daily rotation of the sky. During the day the Sun travels approximately 13 O , and the Moon – 1 O
B. The Sun and Moon move across the sky in a direction aligned with the daily rotation of the sky. During the day the Sun travels approximately 1 O , and the Moon is 13 O . Consequently, the Moon moves across the sky 13 times slower than the Sun.
6. What are the two main factors that constantly change shape? earth's mountains, do not take part in the formation of lunar mountains?
A. Atmosphere and temperature.
B. Water and temperature.
B. Atmosphere and water.
Option II :
1.What explains the significant temperature changes on the lunar surface from day to night?
A. The absence of an atmosphere, as well as the high porosity and low thermal conductivity of the upper layer of the Moon.
B. Lack of atmosphere.
B. High porosity and low thermal conductivity of the upper layer of the Moon.
2. How can we judge the difference in age of the craters observed on the Moon?
A. Because of the basalt type rock.
B. According to the chemical composition of the rock.
B. According to the degree of destruction and sequence of formation.
3. What are the seas that form the “lunar face” with their outlines?
A. Ice blocks.
B. Solid, containing 90% iron.
B. Solidified lava outpourings.
4. Kepler in his book “Lunar Astronomy” wrote: “Levania (the Moon) consists of two hemispheres: one facing the Earth, the other in the opposite direction. From the first the Earth is always visible, from the second it is impossible to see the Earth... In Levania, like here, there is a change of days and nights... It seems that the Earth is motionless.” Is the information about the Moon given by Kepler correct? What is a day on the Moon?
A. The information given by Kepler is practically correct. On moonlit sky The earth is almost motionless. For an astronaut, on most of the lunar surface it does not rise or set. A solar day on the Moon is equal to 29.5 Earth days, and a sidereal day is 27.3 days.
B. The information given by Kepler is not correct. For an astronaut, on most of the lunar surface it does not rise or set. A solar day on the Moon is equal to 29.5 Earth days, and a sidereal day is 27.3 days.
B. The information given by Kepler is practically correct. In the lunar sky, the Earth is almost motionless. For an astronaut, on most of the lunar surface it does not rise or set. A solar day on the Moon is equal to 27.5 Earth days, and a sidereal day is 29.3 days.
5. What is a day on the Moon, how is the Earth visible to an astronaut on the Moon, and are there areas on the Moon where the Earth rises and sets? 5. What is a day on the Moon, how is the Earth visible to an astronaut on the Moon, and are there areas on the Moon where the Earth rises and sets?
A. A solar day on the Moon is equal to 29.5 Earth days. The Earth on the Moon hangs practically motionless in the sky and does not make the same movements as the Moon in the Earth's sky. This is a consequence of the fact that the Moon always faces the Earth with one side. But thanks to the physical librations (swaying) of the Moon, regular sunrises and sunsets of the Earth can be observed from areas near the edge of the lunar disk. The Earth rises and sets (rises above the horizon and falls below the horizon) with a period of about 27.3 Earth days.
B. A solar day on the Moon is equal to 27.3 Earth days. The Earth on the Moon hangs practically motionless in the sky and does not make the same movements as the Moon in the Earth's sky. This is a consequence of the fact that the Moon always faces the Earth with one side. But thanks to the physical librations (swaying) of the Moon, regular sunrises and sunsets of the Earth can be observed from areas near the edge of the lunar disk. The Earth rises and sets (rises above the horizon and falls below the horizon) with a period of about 29.5 Earth days.
B. A solar day on the Moon is equal to 29.5 Earth days. The Earth on the Moon hangs practically motionless in the sky and does not make the same movements as the Moon in the Earth's sky. But thanks to the physical librations (swaying) of the Moon, regular sunrises and sunsets of the Earth can be observed from areas near the edge of the lunar disk. The Earth rises and sets (rises above the horizon and falls below the horizon) with a period of about 29.3 Earth days.
6. How does the history of lunar geological activity differ from that on Earth?
A. 1 billion years after its formation, the Moon became geologically dead celestial body, and on Earth there are volcanoes, mountain building and continental drift occur.
B. 2 billion years after its formation, the Moon became geologically dead heavenly body, and on Earth there are volcanoes, mountain building and continental drift occur.
B. 2 billion years after its formation, the Moon became a geologically dead celestial body, and volcanoes are active on Earth
IY Lesson summary .The conclusion is that the Earth and the Moon constitute a double planet, which distinguishes each of them in the system of planets of the Solar System and their satellites.
V Reflection.
VI Homework § 17; practical tasks.
1. How many sidereal days pass between two successive geocentric conjunctions of the Moon with a certain star near the ecliptic,
if the sidereal period of the Moon is 27.3217 solar days?
2. In the literature you can often find a statement that an observer on Earth always sees the same half of the Moon. Confirm or deny this fact, using the concept of libration and its various types.
Tasks for preparing for the Unified State Exam in Physics
1. The Moon moves around the Earth in a nearly circular orbit at a speed of about 1 km/s. The average distance from the Earth to the Moon is 384 thousand km. Determine the mass of the Earth from these data.
2. The average distance between the centers of the Earth and the Moon is about 60 Earth radii, and the mass of the Moon is 81 times less than the mass of the Earth. Determine at what point on the segment connecting the centers of the Earth and the Moon, spacecraft will be attracted
Earth and Moon with equal strength.
3. The average density of the Moon is approximately 3300 kg/m3, and the radius of the planet is 1700 km. Determine the acceleration of gravity on the surface of the Moon.
Internet resources
:
http://onlinevsem.ru/poleznye-servisy/onlajn-teleskop
http://galspace.spb.ru/index27.html - Planet
Earth and Moon.
http://lar.org.ua/id0391.htm - Life and mind.
The Earth and Moon are a double planet.
2Y - Nature Northern Territory- movement__
Slowing down the speed of rotation of the Earth by the MoonLet's return to the Earth-Moon pair and illustrate some of their interactions with the following figure. For clarity, all scales on it are violated, and the considered distances, forces, speeds, details and processes are repeatedly exaggerated. However, the qualitative side of the phenomena, the essence of the matter, does not suffer from this.
The hypothetical observer is on high altitude, approximately above north pole Earth* (blue ball on the left). Point O1 is both the center of the Earth and the projection of the pole (more precisely, both poles) onto the drawing plane. The yellow ball on the right is the Moon.
*Note(for precision lovers). Due to the tilt earth's axis, it is better for the observer to be not above the pole itself, but at any distant point of the perpendicular established from the center of the Earth in relation to the plane of the Moon’s orbit (which itself does not coincide slightly, by about 5 degrees, with the plane of the Earth’s orbit - the ecliptic). And even more precisely, drawn through the GCM point (see below), and not through the center of the Earth itself. However, none of these three clarifications doesn't change anything in the bycatch mechanism under consideration (but only complicates the understanding of the issue). It does not depend in any way on the location (or presence) of the observer.
Both of these cosmic bodies together rotate (with a periodicity of about 29 days) around them general center masses OCM, and he himself moves along the so-called. "Earth's orbit" around the Sun. (Due to its large radius, it is conventionally shown as a straight line segment). It is somehow not customary to notice the rotation of the Earth itself around the GCM with a lunar (almost monthly) cycle. True, this has almost nothing to do with the problem of tides. (But fairness is important).
Under the influence of the gravitational force of the Moon, the globe (and molten subsoil, and Earth's crust with the oceans, and the atmosphere) turns into ellipsoid, elongated in the direction of the Moon (indicated in red, on the left). The point on the earth's surface 1 closest to the Moon moves to position 2.
Note that this elongation is on average less than one meter. Large difference in water level at sea tides and low tides (in some places on the planet - more than 10 meters) is explained by significant ocean masses of water collected from distances of thousands of kilometers in relatively small shallow waters.
The right (according to the drawing) elevation of the Earth's surface level (point 2) is caused directly by the gravitational force of the Moon. The opposite, left elevation is caused, perhaps, by the specifics of the forces surface tension spherical melt of the planet, which is subject to a lateral force. (The author has no firm confidence in the correctness of this explanation.) In the case of a thick layer of crust (or a completely cooled core), the picture would be similar due to the elastic forces of the solid rocks of the planet.
Other interpreters explain the left elevation by the difference in gravity in different places deformed globe. In the direction perpendicular to the Earth-Moon line, in the low tide zone, the diameter of the Earth is smaller (due to the constancy of the total volume of the planet), which means that gravity is there greatest. And since on average it is unchanged on Earth, it means that on the left there are several smaller. That is why a left elevation is formed there (Perhaps this explanation is correct).
One way or another, in real life ebbs and flows on Earth alternate every 6 hours, so the picture of an ellipsoid elongated in both directions is beyond any doubt.
Due to the relatively rapid rotation of the Earth around its axis ( linear speed surface movement near the equator is approximately 460 m/s), the top of the tidal elevation accumulated at point 2 (no matter whether it is water or land!) is constantly carried away at this speed to the east, to point 3. At point 2, the surface is again slightly raised by the gravitational force of the Moon, but this elevation is again carried away to point 3. Thus, the real position of the top of the tidal rise, point 3, is always shifted in the direction of the Earth’s rotation by an angle of approximately 2 degrees (in the figure indicated by a red arc going from point 2 to point 3 ).
A similar tidal elevation due to the Earth's gravitational force is also present on the solid Moon. According to calculated data, point 5 is elevated above the level of the standard sphere of the Moon (point 4) by 13 meters. Since the Moon is always turned to the earth with one side, the position of point 5 is unchanged both for an terrestrial observer and for an observer located on the Moon itself. (That is, it is a fixed point on the map of the visible part of the Moon).
The gravitational force of the Moon affects not only the entire Earth, but also, in particular, both tidal elevations on Earth. Since the left one is located significantly, almost 13,000 km further, the main impact occurs precisely on the right elevation, the center of which is located at point 3. (This impact is predominant and decisive, so we will only consider it further). Conventionally, it is indicated by force F1. Since its direction does not coincide with the direction to the center of the Earth, it acts on point 3 in such a way as to return it to point 2 (or at least closer to it).
In reality, this work (literally!) is done by force, equal F1, but directed oppositely to it and applied to point 3. This force has a vertical (in the drawing!) component (Ft), directed from t.3 to t.2.
And this component is concrete and real slows down rotation Earth ! Due to this, the length of the earth's day increases annually by 2.10^(-5) seconds. It seems like quite a bit. But what will happen, for example, in a million years? The day will increase by 20 seconds.
And in a few billion years?
The science
Last week there were reports that the “non-planet” Pluto had warmed up another satellite near it. New object, located in the orbit of Pluto, was spotted using space telescope Hubble, and one more was added to the four previously known satellites. But is it really by four?
Now new hypotheses have emerged. For example, that in fact Pluto previously had not 4 satellites, but 3, which were discovered by the same Hubble telescope over the past 7 years. However, a fourth object, called Charon, which was discovered in 1978 and was thought to be a moon of Pluto, is now in doubt. This object may be a planet itself.
Charon's mass is 12 percent of Pluto's mass. This may not seem like much, but, for example, the mass of the Moon is only 1 percent of the mass of the Earth. The remaining moons of Pluto are very small compared to Pluto itself.
Because of this mass ratio, Pluto and Charon seem to waltz around a common central mass. The same thing happens with the Earth and the Moon, but the center of gravity is in this case is within the radius of the Earth. If an outside observer were to look at the Moon and Earth from the outside, he might also assume that these objects resemble a "double planet."
The remaining satellites of Pluto, except Charon, do not rotate exactly in the orbit of Pluto, but follow Keplerian orbits, that is, they rotate around the center of gravity, which is located between Pluto and Charon. Pluto and Charon do full turn around each other in 6.3 days.
This phenomenon is observed in systems double stars. In our galaxy, about half the stars are actually binary systems. It is believed that they were formed due to the fragmentation of a dissipating nebula, the particles of which began to condense to form bodies such as stars.
Since 1993, dozens of binary asteroids have been documented. They could have formed when bodies split into fragments or as a result of collisions between different cosmic bodies. Why is it impossible for double planets to exist? Popular theory states that Charon and other moons of Pluto were formed due to a collision with another icy dwarf planet.
According to a similar theory, our planet's satellite, the Moon, formed approximately 4.4 billion years ago, although this theory has recently been called into question. It is possible that other double planets exist somewhere, but so far no such system has been noticed. These systems may be located outside of debris belts, such as the asteroid belt and the Kuiper belt, where Pluto was discovered.
However, astronomers remain hopeful that double planets may exist and that they may be habitable. The interaction between such worlds could be very interesting. The possibility that Pluto and Charon could be a double system of planets was written about back in 2006, but this hypothesis was somehow hushed up. By the way, Hollywood screenwriters have already taken this opportunity into account; a new science fiction film is coming out in September." Parallel Worlds", which tells the story of events taking place on two planets that are pulled close to each other.