What is the shape of the globe. What is the shape of the Earth

Earth figure is a term for the shape of the earth's surface. Depending on the definition of the figure of the Earth, various systems coordinates

History of the issue Back in the 6th century. BC Pythagoras believed that the Earth was spherical. 200 years later, Aristotle proved this, citing the fact that during lunar eclipses the Earth's shadow is always round. After another 100 years, Eratosthenes, knowing the distance from Alexandria to Syene and using the gnomon near the Library of Alexandria during the position of the Sun above Syene at its zenith, was able to measure the length of the earth's meridian (250,000 stadia) and calculate the radius of the Earth (40,000 stadia). Since it is unknown which stages Eratosthenes used, it is impossible to establish this value in modern units length.

It was Newton who first showed that the shape of the Earth should be different from that of a sphere. He proposed the following thought experiment. It is necessary to dig two mines: from the pole to the center of the Earth and from the equator to the center of the Earth. These mines are filled with water. If the Earth is spherical, then the depth of the mines is the same. But the water in the equatorial mine is affected by centrifugal force, while the water in the polar mine is not. Therefore, to balance the water in both shafts, it is necessary that the equatorial shaft be longer.

Further development of the theory of the figure of the Earth came thanks to the work of Huygens, Cassini, Clairaut, Maclaurin, d'Alembert, Lagrange, Laplace, Legendre, Jacobi, Dirichlet, Poincaré and others.

Modern ideas about the figure of the Earth

To a zero approximation, we can assume that the Earth has the shape of a sphere with an average radius of 6371.3 km. This representation of our planet is well suited for problems in which the accuracy of calculations does not exceed 0.5%. In reality, the Earth is not a perfect sphere. Due to the daily rotation, it is flattened at the poles; the heights of the continents are different; The shape of the surface is also distorted by tidal deformations. In geodesy and astronautics, an ellipsoid of revolution or a geoid is usually chosen to describe the figure of the Earth. A system of astronomical coordinates is associated with the geoid, and a system of geodetic coordinates is associated with the ellipsoid of revolution.

By definition, the geoid is a surface everywhere normal to gravity. If the Earth were entirely covered by ocean and not subject to tidal influences from other celestial bodies and other similar disturbances, it would have the shape of a geoid. In fact, in various places The Earth's surface can differ significantly from the geoid. For better approximation of the surface, the concept of a reference ellipsoid is introduced, which coincides well with the geoid only on some portion of the surface. The geometric parameters of the reference ellipsoids differ from the parameters of the average Earth ellipsoid, which describes earth's surface generally.

In practice, several different mean terrestrial ellipsoids and associated terrestrial coordinate systems are used.

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The problem of the shape of the Earth has concerned people for many millennia. This is one of the important questions not only for geography and ecology, but also for astronomy, philosophy, physics, history and even literature. This issue Many works of scientists from all eras, especially Antiquity and the Enlightenment, are devoted to it.

Scientists' hypotheses about the shape of the Earth

So Pythagoras in the 6th century BC already believed that our planet has the shape of a ball. His statement was shared by Parmenides, Anaximander of Miletus, Eratosthenes and others. Aristotle conducted various experiments and was able to prove that the Earth has a round shape, since during eclipses of the Moon the shadow is always in the shape of a circle. Considering that at that time there were discussions between supporters of absolutely two opposing points of view, some of which argued that the earth was flat, others that it was round, the theory of sphericity, although it was accepted by many thinkers, needed significant revision.

Newton stated that the shape of our planet differs from that of a sphere. He was inclined to believe that it was more likely an ellipsoid, and to prove this, he conducted various experiments. Further, the works of Poincaré and Clairaut, Huygens and d’Alembert were devoted to the shape of the earth.

Modern concept of planet shape

Many generations of scientists have conducted basic research to set the shape of the Earth. Only after the first flight into space was it possible to dispel all the myths. Now the accepted point of view is that our planet has the shape of an ellipsoid, and it is far from perfect shape, flattened from the poles.

For various studies and educational programs a model of the earth has been created - a globe, which has the shape of a ball, but this is all very conditional. It is difficult to depict absolutely everything in scale and proportion on its surface. geographical features of our planet. As for the radius, a value of 6371.3 kilometers is used for various purposes.

For problems of astronautics and geodesy, in order to describe the figure of the planet, the concept of an ellipsoid of revolution or geoid is used. However, at different points the earth differs from the geoid. To solve various problems, they are subsequently used various models terrestrial ellipsoids, for example, the reference ellipsoid.

Thus, the shape of the planet is a difficult question even for modern science, which has worried people since ancient times. Yes, we can fly into space and see the shape of the Earth, but mathematical and other calculations are not yet enough to accurately depict the figure, since our planet is unique and has a different simple form, like geometric bodies.

Who said the earth is round? December 17th, 2014

They say that this is...

However, the hypothesis that our planet is spherical has existed for a very long time. The first to express this idea back in the 6th century BC was the ancient Greek philosopher and mathematician Pythagoras. Another philosopher, Aristotle, who lived in Ancient Greece two centuries later, he provided visual evidence of sphericity: after all, during lunar eclipses, the Earth casts a precisely round shadow on the Moon!

Gradually, the idea that the Earth is a ball hanging in space and not supported by anything spread more and more widely. Centuries have passed, people have long known that the Earth is not flat and does not rest on whales or elephants... We walked around the world, crossed our ball in literally all directions, flew around it on an airplane, photographed it from space. We even know why not only ours, but also all other planets, the Sun, the stars, the Moon, and other large satellites are “round” and not some other shape. After all, they are large and have enormous mass. Their own strength gravity - gravity - strives to give celestial bodies the shape of a ball.

Even if some force, greater than gravity, appeared, which would give the Earth the shape of, say, a suitcase, the end would still be the same: as soon as the action of this force ceased, the force of gravity would begin to collect the Earth again into a ball, “pulling in” protruding parts until all points on the surface are on equal distance from the center.

Let's continue thinking about this topic...

Not a ball!

Back in the 17th century, the famous physicist and mathematician Newton made a bold assumption that the Earth is not a ball, or rather, not quite a ball. He assumed it and proved it mathematically.

Newton “drilled” (mentally, of course!) two communicating channels to the center of the planet: one from the North Pole, the other from the equator, and “filled” them with water. Calculations showed that the water settled at different levels. After all, in a polar well, only the force of gravity acts on the water, but in an equatorial well, it is also opposed by centrifugal force. The scientist argued: in order for both columns of water to exert equal pressure on the center of the Earth, that is, so that they have equal weight, the water level in the equatorial well should be higher - according to Newton's calculations, by 1/230 of the average radius of the planet. In other words, the distance from the center to the equator is greater than to the pole.

To check Newton's calculations, the Paris Academy of Sciences sent two expeditions in 1735 - 1737: to Peru and Lapland. The expedition members had to measure meridian arcs - 1 degree each: one - in equatorial latitudes, in Peru, the other - in polar latitudes, in Lapland. After processing the expedition data, the head of the northern expedition, geodesist Pierre-Louis Maupertuis, announced that Newton was right: the Earth is compressed at the poles! This discovery of Maupertuis was immortalized by Voltaire in... an epigram:

Envoy of physics, brave sailor,
Having overcome both mountains and seas.
Dragging the quadrant among the snow and swamps,
Almost turning into a Lapp.
You found out after many losses.
What Newton knew without walking out the door.

It was in vain that Voltaire was so sarcastic: how can science exist without experimental confirmation of its theories?!

Be that as it may, now we know for sure that the Earth is flattened at the poles (if you like, stretched out at the equator). It is stretched, however, quite a bit: the polar radius is 6357 km, and the equatorial radius is 6378 km, only 21 km more.

Does it look like a pear?

However, is it possible to call the Earth, if not a ball, but an “oblate” ball, namely an ellipsoid of rotation? After all, as we know, its relief is uneven: there are mountains, there are also depressions. In addition, it is affected by the gravitational forces of other celestial bodies, primarily the Sun and the Moon. Even if their influence is small, the Moon is still capable of bending the shape of the liquid shell of the Earth - the World Ocean - by several meters, creating ebbs and flows. This means that the radii of “rotation” are different at different points!

In addition, in the north there is a “liquid” ocean, and in the south there is a “solid” continent covered with ice - Antarctica. It turns out that the Earth does not have a completely regular shape, it resembles a pear elongated towards North Pole. And according to by and large its surface is so complex that it does not lend itself to strict mathematical description. Therefore, scientists have proposed a special name for the shape of the Earth - geoid. The geoid is an irregular stereometric figure. Its surface approximately coincides with the surface of the World Ocean and continues on the mainland. The same “height above sea level” that is indicated in atlases and dictionaries is measured precisely from this geoid surface.

Well, scientifically:

Geoid(from ancient Greek γῆ - Earth and other Greek εἶδος - view, literally “something like the Earth”) - a convex closed surface that coincides with the surface of water in the seas and oceans in a calm state and perpendicular to the direction of gravity at any point. Geometric body, deviating from the figure of rotation An ellipsoid of revolution and reflecting the properties of the gravity potential on the Earth (near the Earth's surface), an important concept in geodesy.

1. The world's oceans
2. Earth's ellipsoid
3. Plumb lines
4. Body of the Earth
5. Geoid

The geoid is defined as the equipotential surface of the earth's gravity field (level surface), approximately coinciding with the average water level of the World Ocean in an undisturbed state and conditionally extended under the continents. The difference between the actual mean sea level and the geoid can reach 1 m.

By definition of an equipotential surface, the surface of the geoid is perpendicular to the plumb line everywhere.

A geoid is not a geoid!

To be completely honest, it is worth admitting that due to the difference in temperature in different parts of the planet and the salinity of the oceans and seas, atmospheric pressure and other factors, the surface of the water surface does not coincide in shape even with the geoid, but has deviations. For example, at the latitude of the Panama Canal, the difference in levels between the Pacific and Atlantic Oceans is 62 cm.

The shape of the globe is affected by strong earthquakes. One of these magnitude 9 earthquakes occurred on December 26, 2004 in South-East Asia, in Sumatra. University of Milan professors Roberto Sabadini and Giorgio Dalla Via believe that it left a “scar” on the planet’s gravitational field, causing the geoid to bend significantly. To test this assumption, the Europeans intend to send a new GOCE satellite, equipped with modern highly sensitive equipment. We hope that he will soon send us accurate information about what shape the Earth has today.

Our planet is one of 9 that revolve around the Sun. Even in ancient times, the first ideas about the shape and size of the Earth appeared.

How have ideas about the shape of the Earth changed?

Ancient thinkers (Aristotle - 3rd century BC, Pythagoras - 5th century BC, etc.) many centuries ago expressed the idea that our planet has a spherical shape. Aristotle (pictured below), in particular, taught, following Eudoxus, that the Earth, which is the center of the Universe, is spherical. He saw proof of this in the character that lunar eclipses have. With them, the shadow cast by our planet on the Moon has a rounded shape at the edges, which is possible only if it is spherical.

Astronomical and geodetic research carried out in subsequent centuries has given us the opportunity to judge what the actual shape and size of the Earth is. Today, everyone knows that it is round, young and old. But there were times in history when it was believed that planet Earth was flat. Today, thanks to the progress of science, we no longer doubt that it is round and not flat. Indisputable proof of this is space photographs. The spherical shape of our planet leads to the fact that the earth's surface is heated unevenly.

But in fact, the shape of the Earth is not quite the same as we used to think. This fact is known to scientists, and it is currently used to solve problems in the field of satellite navigation, geodesy, astronautics, astrophysics and other related sciences. For the first time, the idea of ​​what the actual shape of the Earth was was expressed by Newton at the turn of the 17th-18th centuries. He theoretically substantiated the assumption that our planet, under the influence of gravity, should be compressed in the direction of the axis of rotation. This means that the shape of the Earth is either a spheroid or an ellipsoid of revolution. The degree of compression depends on the angular speed of rotation. That is, the faster a body rotates, the more it flattens at the poles. This scientist proceeded from the principle universal gravity, as well as from the assumption of a homogeneous liquid mass. He assumed that the Earth is a compressed ellipsoid, and determined, depending on the speed of rotation, the dimensions of the compression. After some time, Maclaurin proved that if our planet is an ellipsoid compressed at the poles, then the balance of the oceans covering the Earth is indeed ensured.

Can we assume that the Earth is round?

If planet Earth is viewed from afar, it will appear almost perfectly round. An observer to whom greater measurement accuracy is not important may well regard it as such. The average radius of the Earth in this case is 6371.3 km. But if we, taking the shape of our planet as an ideal sphere, begin to do precise measurements different coordinates of points on the surface, we won’t succeed. The fact is that our planet is not a perfectly round ball.

Different ways to describe the shape of the Earth

The shape of planet Earth can be described in two main, as well as several derivative, ways. It can be taken in most cases as either a geoid or an ellipsoid. It is interesting that the second option is mathematically easy to describe, but the first cannot be described in any way, since to determine the exact shape of the geoid (and, consequently, the Earth), practical measurements of gravity are carried out at various points on the surface of our planet.

Ellipsoid of revolution

Everything is clear with the ellipsoid of rotation: this figure resembles a ball, which is flattened from below and from above. The fact that the shape of the Earth is an ellipsoid is quite understandable: centrifugal forces arise due to the rotation of our planet at the equator, while they do not exist at the poles. As a result of rotation, as well as centrifugal forces, the Earth “fatten”: the diameter of the planet at the equator is approximately 50 km larger than the polar one.

Features of a figure called "geoid"

An extremely complex figure is the geoid. It exists only theoretically, but in practice it cannot be touched or seen. You can imagine the geoid as a surface, the force of gravity at each point of which is directed strictly vertically. If our planet were a regular sphere filled evenly with some substance, then the plumb line at any point would point to the center of the sphere. But the situation is complicated by the fact that the density of our planet is heterogeneous. In some places there are heavy rocks, in others, voids, mountains and depressions are scattered across the entire surface, and plains and seas are also unevenly distributed. All this changes the gravitational potential at each specific point. Is that the form globe- geoid, the ethereal wind that blows our planet from the north is also to blame.

Who studied geoids?

Note that the very concept of “geoid” was introduced by Johann Listing (pictured below), a physicist and mathematician, in 1873.

By it, meaning “view of the Earth” in Greek, was meant a figure, formed by surface The world's oceans, as well as the seas communicating with it, with an average water level, the absence of disturbances from tides, currents, as well as differences in atmospheric pressure, etc. When they say that such and such a height above sea level, this means height from the surface of the geoid at this point on the globe, despite the fact that there is no sea in this place, and it is located several thousand kilometers away.

The concept of geoid was subsequently refined several times. Thus, the Soviet scientist M. S. Molodensky created his theory of determining the gravitational field and figure of the Earth from measurements taken on its surface. To do this, he developed a special device that measures gravity - a spring gravimeter. It was he who also proposed the use of a quasi-geoid, which is determined by the values ​​​​accepted by the gravity potential on the Earth's surface.

More about geoid

If gravity is measured 100 km from the mountains, then the plumb line (that is, a weight on a string) will begin to deviate in their direction. Such a deviation from the vertical is invisible to our eyes, but is easily detected by instruments. A similar picture is observed everywhere: the deviations of the plumb line are larger in some places, and smaller in others. And we remember that the geoid surface is always perpendicular to the plumb line. From this it becomes clear that the geoid is a very complex figure. In order to better imagine it, you can do the following: mold a ball of clay, then squeeze it on both sides to form a flattened shape, then make bumps and dents on the resulting ellipsoid with your fingers. Such a flattened, crumpled ball will show the shape of our planet quite realistically.

Why do you need to know the exact shape of the Earth?

Why do you need to know its shape so precisely? Why do scientists not like the spherical shape of the Earth? Should the picture be complicated by the geoid and the ellipsoid of revolution? Yes, there is an urgent need for this: figures close to the geoid help create coordinate grids, which are the most accurate. Neither astronomical research, nor geodetic surveys, nor various satellite navigation systems (GLONASS, GPS) can exist and be carried out without determining a fairly accurate shape of our planet.

Various coordinate systems

The world currently has several three-dimensional and two-dimensional coordinate systems with global significance, as well as several dozen local ones. Each of them has its own shape of the Earth. This leads to the fact that the coordinates that were determined by different systems are slightly different. It is interesting that, in order to calculate them for points located on the territory of one country, it will be most convenient to take the shape of the Earth as a reference ellipsoid. This has now been established even at the highest legislative level.

Krasovsky's ellipsoid

If we talk about the CIS countries or Russia, then on the territory of these states the shape of our planet is described by the so-called Krasovsky ellipsoid. It was defined back in 1940. Domestic (PZ-90, SK-63, SK-42) and foreign (Afgooye, Hanoi 1972) coordinate systems were created based on this figure. They are still used for practical and scientific purposes. It is interesting that GLONASS relies on the PZ-90 system, which is superior in accuracy to the similar WGS84 system adopted as the basis for GPS.

Conclusion

To summarize, let's say once again that the shape of our planet is different from a sphere. The Earth is approaching its shape to an ellipsoid of revolution. As we have already noted, this question is not at all idle. Precise definition the shape of the Earth provides a powerful tool for scientists to calculate the coordinates of celestial and terrestrial bodies. And this is very important for space and marine navigation, during construction, geodetic work, as well as in many other areas of human activity.

Human space flight is greatest event in the history of mankind. What did the inhabitants of the Earth see through the eyes of the first astronauts? Before the eyes of the world's first astronaut Yu. A. Gagarin closest and deep space, deprived of an airy, light-scattering medium, appeared as a silent kingdom of endless night, universal peace and order, where large, convex, cold and unblinking stars shone against the impenetrable background of velvet darkness, constellations looked like diamond and pearl pendants, countless galaxies and Milky Way. All blue, covered in clouds and rainbow halos, the Earth seemed to be floating in the ocean of the universe.

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https://pandia.ru/text/78/303/images/image004_34.jpg" width="189" height="151 src=">.jpg" align="left" width="333" height="346" src=">Various layers of brightness were visible in the Earth's atmosphere - the result of a dazzling glow in the air, which turned into raging flames of various colors with a predominance of crimson and blue colors. The magical spectacle presented polar shine over Antarctica. These were golden rays, like the teeth of a giant crown. Thunderstorms, flashes of many lightnings, silvery clouds and traces of those burning in the sky looked just as majestic from above. earth's atmosphere meteorites.

Fig.5. Map, compiled With using space pictures

As we approach Earth, our planet appears soft blue with vast blue patches of clouds, green expanses of forests, and yellow-orange zones of steppes and deserts.

We live with you on planet Earth, which rushes through the endless expanse of the Universe, surrounded by a soft blue halo. In the minds of astronauts, the picture of the cosmic abyss with planets and stars amazes the imagination with amazing, unusual, bright, dazzlingly pure colors. According to photographs and, especially, according to the descriptions of astronauts, our Earth in space looks like a silvery-bluish ball, shining in the dark blue expanse of stars flickering with cold light.

As we approach Earth, our planet appears a soft blue with vast patches of ocean and green islands of forest that lie between yellow-orange zones of deserts and steppes.

Interesting fact. The astronaut admitted that he was captivated and fascinated by the picture of the cosmic abyss. You look at the stars - they are motionless, and the Sun seems to be sealed into the velvet of the sky. Only the Earth rushes before my eyes. The endless space was breathtaking. Returning to Earth, A. Leonov painted an amazing picture: an astronaut soars high above the planet, covering part of the Earth’s surface with his shadow. And what amazing, unusual colors - pure, dazzlingly bright.

Now any schoolchild will say that our planet is spherical. And it is very simple to prove this - with a photograph of the Earth taken from space for the first time by an astronaut pilot in 1961.

Thousands of years separate us from the times when people first thought about the shape of the Earth. According to surviving sources, scientists, bit by bit, have restored for us those distant ideas about the shape of our planet. What were they like? Here are some of them.

What were first representation ancient of people O form Earth?

IN Ancient Egypt They believed that the Sun god arises from the boundless waters of the Ocean, which is the beginning of all things. He separates the forces of Heaven and Earth, and therefore is depicted between them, supporting the starry sky with his hands.

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The Egyptians, whose whole life was connected with the Nile Valley, imagined the Earth as oblong, stretching from north to south, like the bottom of a long box. The sky stretched overhead “like a tent to live in.”

Rice. 7. Performance O form Earth at ancient Babylonians

In Ancient Babylon, the Earth was viewed either as an overturned boat, or as a “pyramid temple” with seven floors, and sometimes as a large dome or as a hollow mountain rising from the depths of the Ocean.

Peoples ancient india imagined the Earth to be flat, lying on the backs of three elephants, which were swimming in the vast Ocean on a huge turtle.

Fig.8. Representation O form Earth at ancient Hindus.

The ancient Chinese had myths about an egg-shaped world. However, they imagined the Earth to be square rather than round.

For the first time, the idea that the Earth is not a flat, but a three-dimensional body appeared among ancient Greek scientists. At first, they believed that the Earth as a kind of “circular” body (drum, disk) floats in the Ocean. These ideas were formed not through precise calculations, but speculatively, as a philosophical theory.

The idea of ​​a spherical shape of the Earth was first expressed by ancient Greek scientists Parmenides(c. 540 or 520 BC), who believed that the shape of the ball was ideal.

The first proof of the sphericity of the Earth was given by Aristotle, watching the shadow of the Earth on the surface of the Moon at night.

Rice. 9. Gradual moving shadows Earth on surfaces Moon

By drawing determine which one form It has shadow from Earth on surfaces Moons. ABOUT how This testifies?

The famous ancient Greek mathematician agreed with Aristotle's idea Archimedes(around 2 BC). He believed that since there is on Earth high mountains, plains and deep depressions, then it cannot be an ideal ball. Archimedes was the first to suggest using the term spheroid , denoting a figure close to sphere, but not quite a perfect ball. (A sphere is a closed surface, all points of which are equidistant from the center; the surface and internal space of a ball.)

The idea of ​​an “infallible” round planet existed for a very long time - until the end of the 18th century. But the Earth could only be a perfectly regular sphere if it did not rotate around its axis. Then the substance that makes up the planet would be distributed evenly around its center.

Englishman Isaac Newton(years) and Dutchman Christian Huygens(gg.) proved that the Earth cannot have the shape of a regular sphere. After all, if a spherical body rotates quickly and for a long time around its axis, then it will be compressed at the poles and elongated in the middle. This form was called ellipsoid .

Rice. 10. Ellipsoid.

The Earth shrank at the poles in the distant past, when, according to one hypothesis, it was an uncooled, plastic body. The equatorial part of the Earth moved away from the axis of rotation, and the poles moved closer. As a result, it turned out that the distance from the center to the poles is 6356 km, and from the center to the equator it is 22 km more, and amounts to 6378 km.

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(Geoid – from Greek words ge - Earth, eidos- view, i.e. having the appearance of the Earth, a closed figure, which is taken for the smoothed figure of the Earth.)

Rice. 12. Uneven distribution masses earthly substances

Rice. 13. Geoid

Interesting fact . Looking carefully at Figure 12, it is easy to see that the Northern and Southern hemispheres of the Earth are asymmetrical (from the Greek Asittetri- disproportion, violation of symmetry): one is not a mirror image of the other. What explains this asymmetry of the Northern and Southern hemispheres Earth?

It has been established that the structure and composition of the rocks composing these hemispheres are different. Forces directed parallel to the axis of rotation (namely, from south to north) moved the masses of the earth's matter in the same direction. Therefore, the density of the earth's matter in the Southern Hemisphere decreases and during rotation it experiences greater compression than the Northern Hemisphere. As a result of this, the Earth acquired a rather peculiar shape: South Pole it is slightly concave, in the Northern one it is convex (See Fig. 14). Experts have come up with a name for it: cardioid - heart-shaped figure.

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Polar shine Geoid Horizon Sphere Spheroid Ellipsoid

Check their knowledge

1. Describe How looks Earth from space.

Imagine to myself, What You are back from space flight. U you weight impressions. All are waiting from you interesting stories. ABOUT what impressions, experiences You will you tell me?

2. Which representation O form Earth were at ancient Egyptians?

3. Which representation O form Earth were at ancient Babylonians, Chinese And Indians?

4. Which are common representation O form Earth were at ancient Greek scientists? On how They based?

5. Who And How first proved sphericity Earth?

6. Which amendments V idea sphericity Earth contributed Archimedes? How He named form Earth?

7. Who And How proved What Earth It has form ellipsoid?

8. Why Earth Not Maybe be correct ellipsoid, And which Name given form Earth?

9. How explained asymmetry Northern And Southern hemispheres Earth And How called such form our planets?

10. Imagine, What Earth It has form disk or drum, floating V Ocean. Can whether Then commit around the world journey? Why?

11. Imagine to myself, What You commit mine first space flight. Flying by by Earth, You, undoubtedly saw would, How she beautiful And perfect By form. Why V Space form Earth perceived How ball?

§ 27. What is the earth’s axis and what is the significance of the earth’s rotation around it

Terrestrial axis called an imaginary straight line around which the Earth's daily rotation takes place. The earth's axis passes through the center of the earth and intersects the earth's surface at geographic poles. Its northern end is directed to a point near the North Star.

Find And Show her on drawing 15 earthly axis And Polar star.

Fig. 15. Direction terrestrial axes

The Earth's rotation axis is inclined to the plane of its orbit at an angle 66.5° ( or 23.5° from vertical ). This tilt provides the most favorable conditions for life on most of the Earth.

The Earth rotates around its axis from west to east in the same direction in which it moves along its orbit. The Earth makes a complete revolution around its axis in 24 hours, that is, in a day.

The rotation of the Earth around its axis is called axial or daily allowance

Rice. 16. Rotation Earth around his axes

The axial rotation of the Earth deflects bodies moving horizontally, to the right in the Northern Hemisphere, and to the left in the Southern Hemisphere. As a result, there is a deviation of directions constant winds, displacement of river channels and their erosion of the right banks in the Northern Hemisphere and the left ones in the Southern.

Rice. 17 Valleys rivers V different hemispheres

By drawings determine V what hemispheres are leaking these rivers. By what signs You This determined?

Which meaning It has change day And nights For alive organisms?

As you know, the change of day and night is of great importance for living organisms. You could observe how the flowers of dandelion, calendula and other plants open and close at certain times of the day.

Only in a few habitats (dark caves, lower layers of soil, on deep sea) the change of day and night has practically no effect on living organisms.

During the day, the activity of most animals and plants changes significantly. This phenomenon is called daily allowance rhythm, it is caused by periodic changes in illumination due to the rotation of the Earth around its axis.

Differences in illumination and temperature during the day lead to changes in the intensity of such complex processes in living organisms as formation organic matter, breathing, evaporation of water by plant leaves.

The daily routine of the body’s life is most clearly manifested in periods of wakefulness and sleep, in the need to change active activity and rest. During sleep is coming restoration of vital body processes that protect it from exhaustion.

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Rice. 19. Animals, presenters different image life

So: Earth rotates around imaginary lines - axles, which tilted To plane orbits under angle, equal 66.5°. Full turnover around his axes our planet commits behind period time, which called for days. Behind This time period is happening change day And nights.

Axial rotation Earth rejects bodies, moving horizontally: V Northern hemispheres - right, V South - to the left.

Change day And nights at alive organisms formed daily allowance rhythms V alternation periods activity (awake) And peace (sleep).

Axial rotation Earth * Axis rotation Earth * Day * Daily allowance rotation Earth

* Daily allowance rhythms alive organisms

Interesting fact. There are a number of experiments confirming the rotation of the Earth around its axis. One of them was developed and demonstrated in 1851 by a French physicist Jean Foucault(years). The essence of this experience is as follows. A pendulum - a weight hanging freely on a long thread - when swinging, invariably maintains the plane of its swing. Such a pendulum, attached to the ceiling of a tall building, moves in space along with it due to the rotation of the Earth, but at the same time continues to maintain the direction of its oscillations.

Foucault attached a point to the pendulum's weight, and placed sand rollers on the floor in a circle. As the pendulum swung, the tip left more and more marks in the sand. In Foucault's experiments in Paris, the length of the pendulum was 67 meters; and the cargo weight is 28 kg. The longer the pendulum thread, the slower the swing. The farther from the equator the experiment is carried out, the greater the apparent deflection of the pendulum. At each pole, the discrepancy between the initial direction of the pendulum's swing and the direction after an hour is 15°. At the equator there is no deflection of the pendulum.

Foucault's experience from 1931 until recently was demonstrated in St. Petersburg in St. Isaac's Cathedral. The length of the pendulum was 98 m; and the load had a mass of 60 kg.

Armadillo" href="/text/category/bronosetc/" rel="bookmark">Armadillos - almost all their lives.

For some people, half the dose of sleep is enough. Such people, for example, were Peter I, Napoleon Bonaparte, Thomas Edison.

A person deprived of sleep for a long time begins to see objects as if in a distorting mirror, through a foggy haze. He dreams in reality. Disruption of the rhythm of sleep and wakefulness can lead not only to insomnia, but also to diseases of the cardiovascular, respiratory and digestive systems. Prolonged (more than 10 days) sleep deprivation can lead to death.

Interesting fact. Under the influence of other planets solar system The angle of inclination of the earth's axis increases annually by 0.468". Calculations show that this angle will increase for approximately 15,000 years and then begin to decrease. This explains minor changes direction of the Earth's rotation axis.

Check their knowledge

1. What called axis Earth?

2. Select correct answer: axis Earth Can see on map; photos Earth V space; globe; compass.

3. What such day? Why They equal And How called miscellaneous time days?

4. How Can observe axial rotation Earth?

5. Name consequences rotation Earth around his axes.

6. IN how manifests itself daily rhythm at alive organisms?

7*.On which groups share alive organisms V dependencies from alternation at them periods activity And peace? Bring examples.