Axial rotation of the earth and its consequences briefly. Geographic Consequences of the Earth's Axial and Orbital Rotation

The rotation of the Earth around its axis is manifested in many phenomena on its surface. For example, the trade winds (constant winds in the tropical regions of both hemispheres, blowing towards the equator), due to the rotation of the Earth from west to east, blow from the northeast in the northern hemisphere and from the southeast in the southern hemisphere; in the northern hemisphere, the right banks of rivers are washed away, in the southern - the left; when a cyclone moves from south to north, its path deviates to the east, and so on.

a) b)

Rice. 12 : Foucault pendulum. BUT is the swing plane of the pendulum.

But the most obvious consequence of the rotation of the Earth is the experience with physical pendulum, first posed by the physicist Foucault in 1851.

Foucault's experience is based on the property of a free pendulum to keep the direction of the plane of its oscillations unchanged in space, if no force acts on it, except for gravity. Let the Foucault pendulum be suspended at the north pole of the Earth and oscillate at some point in the plane of a certain meridian l(fig.12, a). After some time, to an observer connected with the earth's surface and not noticing its rotation, it will seem that the plane of the pendulum's oscillations is continuously shifting in the direction from east to west, “behind the Sun”, i.e. clockwise (Fig. 12, 6 ). But since the swing plane of the pendulum cannot arbitrarily change its direction, we have to admit that in reality the Earth turns under it in the direction from west to east. In one sidereal day, the plane of oscillation of the pendulum will make full turn relative to the earth's surface angular velocity w= 15° at the sidereal hour. At the south pole of the Earth, the pendulum will make 24 finest hour also one turn, but counterclockwise.

Fig 13.

If the pendulum is suspended on the earth's equator and the plane of its swing is oriented in the plane of the equator, i.e. at a right angle to the meridian l(Fig. 12), then the observer will not notice the displacement of the plane of his oscillations relative to terrestrial objects, i.e. it will appear stationary and remain perpendicular to the meridian. The result will not change if the pendulum at the equator oscillates in any other plane. It is usually said that at the equator the period of rotation of the oscillation plane of the Foucault pendulum is infinitely large.

If the Foucault pendulum is hung at latitude j, then its oscillations will occur in a plane vertical for a given place on the Earth.

Due to the rotation of the Earth, it will seem to the observer that the plane of oscillation of the pendulum rotates around the vertical of this place. The angular velocity of this rotation w j is equal to the projection of the vector of the angular velocity of the Earth's rotation w onto the vertical in this place O(Fig. 13), i.e.

w j --= w sin j= 15°sin j.

Thus, the angle of apparent rotation of the plane of oscillation of the pendulum relative to the Earth's surface is proportional to the sine of geographic latitude.

Foucault staged his experience by hanging a pendulum under the dome of the Pantheon in Paris. The length of the pendulum was 67 m, lentil weight - 28 kg. In 1931 in Leningrad in the building St. Isaac's Cathedral a pendulum 93 long was suspended m and weighing 54 kg. The oscillation amplitude of this pendulum is 5 m, the period is about 20 seconds. The point of his lentils at each next return to one of extreme provisions shifted to the side by 6 mm. Thus, in 1-2 minutes you can make sure that the Earth really rotates around its axis.

Rice. fourteen

The second consequence of the Earth's rotation (but less obvious) is the deflection of falling bodies to the east. This experience is based on the fact that the farther a point is from the axis of rotation of the Earth, the greater its linear speed with which it moves from west to east due to the rotation of the Earth. Therefore, the top high tower AT moves to the east with a greater linear speed than its base O(Fig. 14). The motion of a body freely falling from the top of the tower will occur under the action of the force of gravity of the Earth with initial speed top of the tower. Consequently, before falling to the Earth, the body will move along an ellipse, and although the speed of its movement gradually increases, it will fall to the Earth's surface not at the base of the tower, but will somewhat overtake it, i.e. deviate from the base in the direction of the rotation of the Earth, to the east.

AT theoretical mechanics to calculate the magnitude of the deviation of the body to the east X the formula is obtained

where h- body fall height in meters, j - geographical latitude places of experience, and X expressed in millimeters.

The phenomena of daily rhythm and biorhythms are associated with axial movement. The daily rhythm is associated with light and temperature conditions. Biorhythms are important process in the development and existence of life. Without them, photosynthesis, the vital activity of diurnal and nocturnal animals and plants and, of course, the life of the person himself (owl people, lark people) are impossible.

Currently, the rotation of the Earth is directly observed from space.

Earth (lat. Terra) - the third planet from the Sun solar system, the largest in diameter, mass and density among the terrestrial planets.

The earth interacts (attracts gravitational forces) with other objects in space, including the Sun and Moon. The Earth revolves around the Sun and makes a complete revolution around it in about 365.26 days. This period of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° relative to its orbital plane, which causes seasonal changes on the planet's surface with a period of one tropical year (365.24 solar days).

One of the evidence orbital rotation Earth is the change of seasons. Right Understanding observed celestial phenomena and the place of the Earth in the solar system has evolved over the centuries. Nicolaus Copernicus finally broke the idea of the immobility of the Earth. Copernicus showed that it was the rotation of the Earth around the Sun that could explain the apparent loop-like motions of the planets. Center planetary system is the Sun.

The axis of rotation of the Earth is deviated from the axis of the orbit (i.e., straight, perpendicular to the plane orbit) at an angle of approximately 23.5°. Without this tilt, there would be no change of seasons. The regular change of seasons is a consequence of the movement of the Earth around the Sun and the inclination of the Earth's axis of rotation to the plane of the orbit. In the northern hemisphere of the Earth, summer comes, when the north pole of the Earth is illuminated by the Sun, and the south pole of the planet is located in its shadow. At the same time, winter is coming in the southern hemisphere. When it's spring in the northern hemisphere, it's autumn in the southern hemisphere. When it's autumn in the northern hemisphere, it's spring in the southern hemisphere. The seasons in the southern and northern hemispheres are always opposite. Around March 21 and September 23 around the world, day and night last 12 hours. These days are called the spring and autumn equinoxes. In summer, the duration of daylight hours is longer than in winter, therefore, the northern hemisphere of the Earth during spring and summer from March 21 to September 23 receives much more heat than in autumn and winter from September 23 to March 21.

As you know, the Earth revolves in its orbit around the Sun. For us, people on the surface of the Earth, such an annual movement of the Earth around the Sun is noticeable in the form of an annual movement of the Sun against the background of stars. As we already know, the path of the Sun among the stars is a great circle. celestial sphere and is called the ecliptic. This means that the ecliptic is a celestial reflection of the Earth's orbit, so the plane of the Earth's orbit is also called the plane of the ecliptic. The axis of rotation of the Earth is not perpendicular to the plane of the ecliptic, but deviates from the perpendicular by an angle. Due to this, the seasons change on Earth (see Fig. 15). Accordingly, the plane of the earth's equator is inclined at the same angle to the plane of the ecliptic. The line of intersection of the plane of the earth's equator and the plane of the ecliptic retains (if precession is not taken into account) an unchanged position in space. One end points to the vernal equinox, the other to the autumn equinox. These points are fixed relative to the stars (up to precessional motion!) and together with them participate in daily rotation.

Rice. fifteen.

Near March 21 and September 23, the Earth is located relative to the Sun in such a way that the boundary of light and shadow on the Earth's surface passes through the poles. And since every point on the surface of the Earth makes diurnal movement around the earth's axis, then exactly half of the day it will be on the illuminated part the globe, and the second half - on the shaded one. Thus, on these dates, day equals night, and they are named accordingly. days spring and autumn equinoxes. The Earth at this time is on the line of intersection of the planes of the equator and the ecliptic, i.e. at the spring and autumn equinoxes, respectively.

We single out two more special points in the Earth's orbit, which are called solstices, and the dates on which the Earth passes through these points are called solstices.

At the point of the summer solstice, at which the Earth is near June 22 (the day of the summer solstice), the north pole of the Earth is pointing towards the Sun, and most days, any point of the northern hemisphere is illuminated by the Sun, i.e. This date is the longest day of the year.

At the point of the winter solstice, at which the Earth is near December 22 (the day of the winter solstice), the north pole of the Earth is directed away from the Sun, and for most of the day any point of the northern hemisphere is in the shade, i.e. on this date, the night is the longest of the year, and the day is the shortest.

Because of calendar year does not coincide in duration with the period of revolution of the Earth around the Sun, the days of the equinoxes and solstices in different years may fall on different days(-+ one day from the above dates). However, in the future, when solving problems, we will neglect this and assume that the days of equinoxes and solstices always fall on the dates indicated above.

Let's move on from real movement Earth in space to visible movement Sun for an observer at latitude. During the year, the center of the Sun moves in a large circle of the celestial sphere, along the ecliptic, counterclockwise. Since the plane of the ecliptic in space is fixed relative to the stars, the ecliptic, together with the stars, will participate in the daily rotation of the celestial sphere. Unlike celestial equator and the celestial meridian, the ecliptic will change its position relative to the horizon during the day.

How do the coordinates of the Sun change during the year? Right Ascension changes from 0 to 24 h, and the declination changes from - to +. This can best be seen on heavenly map equatorial zone(Fig. 16).

Rice. 16.

For four days in a year, we know the coordinates of the Sun exactly. The table below provides this information.

Table 2. Data on the Sun during the equinoxes and solstices

t. sunrise	t.	h max
	0 h 00 m
23 o 26"	6 h 00 m	north-east
	12 h 00 m
23 o 26"	18 h 00 m

The table also shows the noon (at the time of the upper culmination) height of the Sun for these dates. In order to calculate the height of the Sun at the moments of culminations on any other day of the year, we need to know that day.

All planets move in the universe. These movements are due to different physical influences on cosmic bodies and have complex nature. The earth also makes many movements that can be analyzed and decomposed into different components.

These movements can be classified in scales:

the universe;
Galaxies;
solar system;
common center of mass with the Moon;
Earth.

The galaxy in which the solar system is located is called the Milky Way. Scientists suggest that this galaxy revolves around the center of the universe along with other galaxies. The solar system with all objects, including the Earth, revolves around the center of the Milky Way, and it completes this path in one galactic year, which is approximately 230 million years.

When moving to an even smaller scale, it will be found that our planet makes a path around the sun. In addition, the Earth and the Moon revolve around their common center mass, which is not located in the center of the globe, but close to its surface. Because of this, our planet orbits in a slightly helical path when viewed from the side rather than from Earth. All these types of movements are imperceptible or barely noticeable to earthlings.

Rotational speed

You can say that the rotation of the body has two speeds, depending on which measurement system to use:

linear;
angular.

If we measure the speed of rotation as the distance that a point travels in certain time, then the further the point is located from the imaginary axis of rotation, the higher its speed will be. And the closer the point is to the axis, the lower its speed. This speed is called linear. At the points of the axis - the speed is equal to zero.

But if the speed of rotation is measured in degrees, then any point on the surface of the body or inside it will move at the same speed, regardless of whether it is far from the axis or close. The speed of rotation, measured in degrees, is called angular.

Can be measured earth rotation speed by observing the movement of two objects on the surface, located on the same meridian, but at different latitudes. Let's say object A will be at the equator, and object B will be at northern latitude. As a result, it will be found that the object, A relative to the axis of the planet, has traveled a distance per unit of time greater than the object B. This means that the object, A, was moving faster than the object B.

But if you measure the angular velocity in degrees for the same objects or marks, then they will have the same angular velocity, since they will rotate relative to the planet's axis by the same angle in a certain period of time. For the study of many natural phenomena, such as, for example, the Coriolis force, it is necessary to use linear way rotation speed measurements.

At the Earth, the surface around the equator will have the maximum linear speed of rotation, and this speed is 465 m/s or 1674 km/h. How closer point on the surface of the globe to any of the poles, the lower will be the speed. At the poles, the linear speed of rotation is zero, since these points are on an imaginary axis.

Change of time of day

The most noticeable circumstance for the inhabitants of the Earth and the main geographical consequence axial rotation our planet is the change of seasons, and for earthlings living at a certain distance from the equator - also the seasons.

Day and night change because that parallel rays of light from the Sun hit only one side of the planet at a time. The opposite side of the Earth is in shadow. This means that on the side turned to the star there will be day, and on the opposite side - night. If the globe were constantly turned with only one side towards the Sun, then on the illuminated side there would be a temperature of about + 100 ° C, all the water would have to evaporate, and on dark side the surface of the planet would be under a layer of ice. Conditions on both sides of the Earth in this case would be unsuitable for life.

Due to the rhythm of the change of day and night, the seasons, and, therefore, light and temperature conditions, on Earth, all living things obey certain biorhythms. At the same time, not only all plants and animals are subject to rhythmic changes, but also inanimate nature.

The earth rotates on its axis counterclockwise when viewed from the side polar star, namely with north side. And if the observation point is from the side of the equator, when North Pole above, then the planet rotates from left to right or from west to east.

In connection with the rotation of the Earth around its axis, the concept of a day is used. But the days are different:

stellar;
sunny;
average sunny.

Sidereal days are used for astronomical research and observations. A solar day is the period of rotation of the Earth around its axis relative to the Sun. They may vary in duration, so to measure time in Everyday life averages are used solar day that last 24 medium solar hours and longer than a sidereal day by 4 minutes.

Time Zones

With the development of communications between different parts of the world, time zones were invented for convenience and safety. Most of all, such unification was in demand in order to eliminate confusion and accidents on railway.

Accurate time measurement using time zones began to be used in the 19th century. The first person to come up with this idea was English doctor William Hyde Wollaston. The earth's surface was conditionally divided into 24 sectors perpendicular to the equator, each of which is 15 degrees, and together they determine the daily cycle. Each zone has its own time (with a difference of one hour from the next one). At the same time, the further to the west the belt is located, the more time lags behind.

If the boundaries of the time zone do not coincide with state or administrative outlines, they are adjusted for convenience to the area. Therefore, time zone boundaries are not always straight. Their countdown starts from zero, located on Greenwich meridian . This belt indicates universal time.

Change of seasons

The axis of the Earth relative to the plane of the orbit along which the planet moves around the Sun is not perpendicular, but at an angle. Because of this, an uneven amount of heat from the Sun hits the surface of the planet in its different parts.

When the Earth is in orbit on one side of the Sun, it is tilted with its axis so that the North Pole faces the star, but, having moved along the orbit by opposite side from the Sun, the planet will be tilted by the South Pole. This means that, in the first case, summer will be in the Northern Hemisphere, and in the Southern - winter. In the second case, it will be winter in the Northern Hemisphere, and summer in the Southern Hemisphere. In the intermediate positions of the Earth in orbit on its hemispheres there will be autumn and spring.

If the Earth's axis were perpendicular to the plane of its orbit, then there would be no seasons, since the Northern and Southern hemispheres would always receive the same portion of light and heat during the day.

Deflection of falling bodies

All objects on the surface of the Earth move along with it at the same linear speed, caused by the rotation of the planet around its axis. The farther from the axis there is an object moving with the planet, the higher its speed will be. The higher the object above the surface, the greater the linear speed it moves with the Earth around its axis.

Items thrown from high altitude, initially move along with the Earth and fall to the ground, slightly shifted to the east. This is due to inertia., which is preserved by an object thrown from a height. He maintains the speed he was at his best. This speed is always higher than on the surface of the Earth. During the fall, this eastward velocity is perpendicular to the fall velocity.

As a result, the object does not fall vertically, but slightly to the east. At the poles, this effect will not be due to the lack of linear speed of movement. Airplane or other aircraft are not suitable for conducting such an experiment, since they are not rigidly connected with the earth's surface and do not move synchronously with it. For this, a tower or high building.

Foucault pendulum

This experiment is the simplest and most obvious test of the Earth's axial rotation.

According to the law of physics, the plane of the trajectory of a swinging pendulum is always in the same position with respect to the World space. But, if you follow the pendulum during the day, it becomes obvious that the direction of its swings is constantly changing. This is due to the rotation of the planet around own axis.

This pendulum was first used in his experiment by the French scientist Jean Foucault, after whom the instrument was named.

Compression of the Earth from the poles

During rotation, centrifugal force arises, which is no exception in the case of planets. In this way, Under the influence centrifugal force , acting perpendicular to the axis is especially strong in the equator region, our planet for a long time acquired the shape of an ellipsoid (a ball flattened from the poles).

The influence of the gravity of the moon

The natural satellite of the Earth has an impact not only on the earth's surface, but also on the layers that lie under it. This happens under the influence of gravity or gravity. Most of all, the gravity of the moon is visible on the surface of the oceans. earth water is attracted by the satellite and forms a wave that follows the moon. The satellite moves around the earth in opposite direction the rotation of our planet on its axis. And, since the rotation of the globe around its axis is faster than the movement of the satellite around the Earth, tidal wave does not move from east to west how the moon moves, and from west to east.

This opposite movement contributes to the gradual slowing down of the rotation of both celestial bodies. The Moon is always located in relation to the Earth on one side. Scientists argue that in the distant future the same will happen to our planet, that is, both celestial bodies will be directed towards each other by one of their sides and will continue to rotate around their common center of mass.

Coriolis force

The body that does rectilinear motion in a rotating medium, deviates to the side relative to this medium. Such a rotating medium is called a non-inertial coordinate system. The Earth is such a system. If the medium rotates clockwise, then the body moving in this system will deviate to the left, relative to the medium. When the non-inertial system rotates counterclockwise, the body deviates to the right.

For example, it will look like this: if a cannon at the North Pole fires a cannonball in the direction of the equator, then for an observer on Earth, the cannonball will gradually deviate to the right. This is because the planet moves, rotating around its axis, and while the core flies, it has time to turn. If the observer is not on the Earth, that is, does not move with it, then the motion of the nucleus will be rectilinear.

AT southern hemisphere such a deviation of moving bodies will occur to the left, since, if viewed from the side South Pole, the planet rotates around its axis clockwise.

This effect is called the Coriolis force.. It is named after the French scientist who discovered the phenomenon. It is noteworthy that this principle is valid for any direction of the body along earth's surface. If you shoot a cannonball from a cannon located on the equator towards the North Pole, then the projectile for an observer on Earth will deviate to the right, just like when reverse direction, that is, when shooting from the North Pole to the equator.

When firing from the equator to the South Pole, the projectile will deviate to the left, as when firing from the South Pole to the equator. This effect is observed due to the inertia of the core, directed towards the rotation of the planet. At the beginning of the movement, the projectile was at the equator (at the earth's point with the highest speed resulting from axial rotation). As the nucleus moves towards the pole, it flies over points on the earth's surface that move slower than the equator, and, therefore, the lateral movement of the nucleus, which is preserved due to inertia. Thus, the core gradually "overtakes" the earth's surface in the lateral direction and deviates to the side.

The Coriolis force always acts perpendicular to the motion of an object. This force acts not only on bodies moving in the direction of the meridians, but also in any other direction, regardless of which direction the movement occurs.

It is not entirely correct to call the Coriolis force a force, since, in fact, it does not pull anyone anywhere by itself. This effect is strictly relative and exists only in a non-inertial system.

But the consequences of this effect are quite palpable. For example, due to the Coriolis force, cyclones form on the planet. Air from zones high pressure tends to a region of low pressure and the Coriolis force deflects air masses relative to the moving surface to the right or left, depending on the hemisphere. Therefore, cyclones twist counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere.

The Coriolis force acts on rivers and their channels. In the Northern Hemisphere, usually the right banks of the rivers are steeper and washed away by water, which is pulled to the right by the rotating planet, in the Southern - on the contrary, the left.

Railroad tracks are also affected given force. The right rails of single track roads in the Northern Hemisphere will wear more as the train pulls to the right. In the Southern Hemisphere, left rails wear out more.

These are general consequences rotation of our planet around its axis, which, in turn, affect great amount circumstances and events both on Earth and around it. Similar topic disclosed in the textbook on geography "Axial rotation of the earth" Grade 5.

The Earth simultaneously rotates around its axis, moves around the Sun, near the common centers of gravity with the Moon and near the centers of gravity common to the entire Solar System, and also moves around the nucleus of the Galaxy as part of the Solar System. However, for life on the planet, the main processes are the axial and orbital movements of our planet. The earth rotates from west to east counterclockwise and makes a complete rotation around its axis in 23 h 56 min 4,1 With(sidereal day).

An imaginary straight line around which the Earth revolves is taken as the earth's axis. The earth's axis intersects with the earth's surface at two points, called the poles - North and South.

The equator is a great circle formed by the intersection of the Earth, perpendicular to the axis of rotation at a distance equal to both poles. If you mentally cross the Earth with a number of planes parallel to the equator, lines will appear on the earth's surface, called parallels having a west-east direction. When the Earth is mentally crossed by planes passing through the axis of its rotation, lines appear on the surface of the Earth, called meridians having a north-south direction. The linear speed of rotation of all points on one meridian decreases from the equator to the poles.

Period of complete axial rotation of the Earth- day. They are taken for natural unit time measurements. The length of time it takes for the Earth to rotate on its axis with respect to the Sun is called true solar days. The solar day is somewhat longer than the sidereal day, which is explained by the simultaneous rotation of the Earth around its axis and its movement around the Sun. At the same time, the Earth changes speed during its orbital movement: being closer to the Sun (at perihelion), it moves faster, and further (at aphelion) it moves more slowly. This leads to the fact that the duration of the true solar day is not the same throughout the year. For convenience, true solar time replaced by the mean solar, which is always 24 h. The moment of the lower culmination of the mean Sun is taken as the beginning of the day, i.e. midnight.

The day begins simultaneously on the entire meridian. Each meridian has its own local time, and the further east it is located, the earlier the day begins on it. Rotating, the Earth turns 15 o in 1 hour, therefore, on meridians 15 o apart from each other, local time differs by 1 hour. If the distance between the meridians is 1 o, the time difference is 4 minutes. The local time inconvenient due to differences in time between neighboring points located on different meridians, therefore, in late XIX in. introduced standard time, dividing the entire surface of the Earth into 24 time zones of 15 about each. When crossing the border, the time changes by 1 hour.

The initial belt runs on both sides of the zero meridian, called Greenwich. Time prime meridian accepted as universal time. The boundaries of the belts are not always drawn along the meridians, but taking into account political, administrative and economic boundaries. The boundaries of the belts are not always drawn along the meridians, but taking into account political, administrative and economic boundaries.

In order to save energy and make better use of solar lighting by the population in morning hours in many countries, including Russia, at the end of March, the clock hands were moved 1 hour ahead. This time is called summer. At the end of October, the hands were moved back 1 hour - this winter time, corresponding to the belt. In 2011, winter time was canceled in Russia.

When moving from one time zone to another, you need to move the clock hands forward if you are moving east, or backward if you are moving west. In the end world travel from west to east, the arrows will be moved forward 24 hours, i.e. one day will be "lost". In order for the time to be correct when flying from one hemisphere to another, they established conditional line - international date line. It runs along the 180th meridian in pacific ocean and does not cross land. When crossing this line from east to west, one day is discarded from the account, i.e. after September 1, 3 will come, and when crossing this line from west to east, the same number will repeat the next day. The earth rotates on its own axis and at the same time revolves around the sun. average speed 30 km/s. With such high speed it makes a complete revolution around the Sun in 365 days 5 hours 48 minutes 46 seconds.

This period is called astronomical year . The path that the earth takes around the sun is called orbit. The orbit is a closed curve shaped like an ellipse 940 million km long. The sun is not in the center, but shifted to the side - to one of the foci, so the distance from the Earth to the Sun varies depending on the position of the Earth in orbit. The seasons on earth exist because earth's axis is not at right angles to the plane of the orbit. When moving in orbit, the direction of the earth's axis does not change and is always directed towards the North Star.

night can be equal at all latitudes only at the moment when the terrestrial

the axis lies in the light-separating plane, and the light-separating line passes through geographic poles. it day of spring equinox.Then every day until June 21, the Sun at noon is at its zenith at more northern points planets. In the Northern Hemisphere, summer occurs when the N Pole is tilted towards the Sun. June 22 is called summer solstice day. The sun is at its zenith on the parallel 23 o 27 ΄ with. sh. This parallel is called the Northern Tropic - the Tropic of Cancer. At this time, the longest duration of the light part of the day, it does not change for several days. At the same time, on the parallel 66 about 33΄ s. sh. up to 90° the Earth is completely illuminated and does not fall into the shadow during rotation. There is no change of day and night. This time is called polar day. After June 22, all these phenomena occur in reverse order until September 23, the Sun is again at noon at the zenith on the equatorial line and the line separating the illuminated hemisphere from the unilluminated one passes through the poles. it sunny day(autumn) equinoxes.

The earth continues to move in orbit and turns more and more towards

the sun in its southern hemisphere. On December 22, the Sun at noon is at its zenith at its most southern points on parallel 23 about 27΄ S. sh., which

called the southern tropic - the tropic of Capricorn. This is the second solstice of the year - summer in the Southern Hemisphere. At this time, north of the North polar circle happens polar night, and south of the Antarctic Circle - polar day. It became possible to establish the age of the Earth after the discovery of the phenomenon of radioactivity. It became clear that radioactive nuclei decay with constant speed, independent of changes in the surrounding physico-chemical conditions. In nature, there are elements contained in minerals, radioactive decay which is used in the geological chronology. These are U238, U235, Th232, K40, Rb87, C14.

Absolute age rock is determined from the quantitative

relations in it radioactive element and its decay products.

long time considered to be the most ancient rocks Earth 3.8-3.9 billion years. They are found in Eastern Siberia, in Western Greenland, in Antarctica. Later, in Australia, in sandstones aged 2.9 billion years, the mineral zircon was discovered, which is 4.3 billion years old. Zircon got into sandstones during the destruction of older rocks. As a result of the processing of terrestrial and lunar rock samples, meteorites

their age is established - 4.55 billion years.

So, it is assumed that the earth-like planets have an age of 4.6-4.55 billion years, and the age of the Sun is 4.65-4.6 billion years

Just as the earth revolves around the sun, Moon- natural satellite our planet, located at a distance of 384,000 km. The diameter of the moon is 4 times, and the mass is 81 times smaller than Earth, so the gravitational force on the moon is about 6 times less than the earth.

Weak strength gravity does not allow the moon to retain a dense atmosphere and keep water on its surface. The Moon has a very weak magnetic field and no iron core. The moon is covered with a loose layer of regolith, consisting of fractions igneous rocks. The mineralogical composition of lunar rocks is close to that of terrestrial basalts, but differs in the content of iron and titanium oxides. Regolith is a good heat insulator that does not allow sharp temperature fluctuations (from +130 to -170 ° C) to penetrate deeper than several tens of centimeters. Yes, during lunar day, which lasts 15 Earth days, the rays of the Sun glow lunar soil near the equator to 130 o C. During the night, which also lasts 15 Earth days, the soil cools down to -70 o C. origin. In separate places lunar surface a small outflow of volcanic gases was recorded.

The moon makes a full circle in the sky in 27 days 7 hours 43 minutes - this is sidereal month called sidereal. The origin of the Moon is the subject of a number of hypotheses. It is assumed that 1) the formation of the Moon from the same gas-dust cloud proceeded simultaneously with the Earth; 2) The earth rotated very quickly and threw off part of its substance; 3) there was a capture of the Moon as a foreign body by the Earth; 4) there was a gliding impact on the Earth of a cosmic body, the mass of which corresponds to the mass of Mars and the release of the substance of the Earth's mantle into near-Earth space, followed by the formation of the Moon from this substance. Since the composition of lunar rocks is close to the composition of the Earth's mantle matter, the latter hypothesis is the most popular.

Under the influence of the Moon's attraction, the Earth's body experiences an elastic de-

formation, taking the form of a symmetrical egg, extended towards the Moon along a line connecting the centers of the Earth and the Moon. undergoes a particularly noticeable deformation. water shell Earth. At the point of the ocean surface closest to the Moon and at the diametrically opposite point, swelling is formed water mass(tidal protrusion), and on a circle located in the middle between these points perpendicular to the line Earth - Moon, a decrease occurs water surface. Due to the rotation of the Earth, tidal bulges turn into a tidal wave that goes around the globe, moving towards the rotation of the Earth, i.e. from east to west. The passage through some place of the crest of a wave creates a tide here, the passage of a hollow of a wave creates an ebb. During lunar day There are two rises and two falls in sea level. The time interval between two adjacent highest (or lowest) level stands is 12 h 25 min. During the new moon and full moon, when the sun and moon are located almost on the same straight line, the tidal influences of both space bodies add up, and the tides on Earth reach their greatest height. When the directions to the Moon and the Sun form a right angle, their influences are subtracted, and the tides on Earth are at their lowest.

The material gives an idea of what the axial rotation of the planet is. Reveals the mystery of the rising and setting of the sun and indicates the factors that influence the shape of the earth as a result of its rotation.

Axial rotation of the earth and its consequences

Thanks to astronomical observations a fact has been established which proves that the Earth simultaneously receives Active participation in several types of movement. If we consider our planet as part of the solar system, then it makes revolutions around the center Milky Way. And if we consider the planet as a unit of the Galaxy, then it is already a participant in the movement at the galactic level.

Rice. 1. Axial rotation of the earth.

The main type of motion that has been studied by scientists since ancient times is the rotation of the Earth around its own axis.

The axial rotation of the Earth is called its measured rotation around the represented axis. All objects that are on the surface of the planet also rotate with it. The rotation of the planet is made in the opposite direction relative to the usual clockwise movement. Thanks to this, the sunrise can be celebrated in the east, and the sunset in the west. The Earth's axis has an angle of inclination equal to 661/2° relative to the orbital plane.

The axis has clear reference points in space: its northern tip all the time facing the North Star.

The axial rotation of the Earth gives an idea of the apparent movement of celestial bodies without the use of specialized equipment.

Effect of axial rotation on the shape of the earth

Planet Earth is a perfect sphere. But due to the fact that it is slightly compressed at the poles, the distance from its center to the poles is 21 kilometers less than the distance from the center of the Earth to the equator. Therefore, the meridians are 72 kilometers shorter than the equator.

Axial rotation causes:

diurnal changes;
the flow of light and heat to the surface;
the ability to observe the obvious movement of celestial bodies;
time differences in different parts earth.

To understand how axial rotation affects the shape of the earth, one must take into account the operation of generally accepted laws of physics. As already noted, the planet has a "flattening" at the poles due to the action of centrifugal force and gravity on it.

The planet rotates in the same way as it moves around the sun. Quantities such as the shape, parameters and motion of the Earth play big role in the development of all geographical phenomena and processes.

Today it is reliably known that the Earth is actually gradually slowing down its rotation. Due to the strength of the tides that connect our planet with the moon, every century the day becomes longer by 1.5-2 milliseconds. In almost one and a half million years there will be one hour more in a day. People should not be afraid of a complete stop of the Earth. Civilization simply will not live up to this point. Approximately in 5 billion years, the Sun will increase in size and swallow our planet.4.6. Total ratings received: 181.

The earth rotates around its axis from west to east, that is, counterclockwise, if you look at the earth from the North Star (from the North Pole). In this case, the angular velocity of rotation, i.e., the angle by which any point on the surface of the Earth rotates, is the same and amounts to 15 ° per hour. Linear speed depends on latitude: at the equator it is the highest - 464 m / s, and the geographical poles are fixed.

The main physical proof of the rotation of the Earth around its axis is the experiment with Foucault's swinging pendulum. After the French physicist J. Foucault carried out his famous experiment in the Paris Pantheon in 1851, the rotation of the Earth around its axis became an indisputable truth.

Physical evidence of the Earth's axial rotation is also measured by the 1° meridian arc, which is 110.6 km at the equator and 111.7 km at the poles. These measurements prove the compression of the Earth at the poles, and it is characteristic only of rotating bodies. And finally, the third proof is the deviation of falling bodies from the plumb line at all latitudes, except for the poles. The reason for this deviation is due to the preservation by inertia of a greater linear velocity of point A (at a height) compared to point B (near the earth's surface). Falling objects are deflected on the Earth to the east because it rotates from west to east. The magnitude of the deviation is maximum at the equator. At the poles, bodies fall vertically, without deviating from the direction of the earth's axis.

The geographical significance of the axial rotation of the Earth is exceptionally great. First of all, it affects the figure of the Earth. The compression of the Earth at the poles is the result of its axial rotation. Previously, when the Earth rotated at a higher angular velocity, the polar contraction was more significant. Lengthening of the day and, as a result, a decrease in the equatorial radius and an increase in the polar one is accompanied by tectonic deformations earth's crust(faults, folds) and the restructuring of the Earth's macrorelief.

An important consequence of the axial rotation of the Earth is the deviation of bodies moving in a horizontal plane (winds, rivers, sea currents, etc.) from their original direction: in the northern hemisphere - to the right, in the southern hemisphere - to the left (this is one of the forces of inertia, called the Coriolis acceleration in honor of the French scientist who first explained this phenomenon). According to the law of inertia, every moving body strives to keep the direction and speed of its movement in the world space unchanged.

Deviation is the result of the fact that the body participates simultaneously in both translational and rotational movements. At the equator, where the meridians are parallel to each other, their direction in world space does not change during rotation and the deviation is zero. Towards the poles, the deviation increases and becomes greatest at the poles, since there each meridian changes its direction in space by 360 ° per day. The Coriolis force is calculated by the formula F=m*2w*v*sinj, where F is the Coriolis force, m is the mass of the moving body, w is the angular velocity, v is the speed of the moving body, j is the geographic latitude. The manifestation of the Coriolis force in natural processes is very diverse. It is because of it that vortices of various scales arise in the atmosphere, including cyclones and anticyclones, winds deviate from the gradient direction and sea currents, influencing the climate and through it the natural zonality and regionality; the asymmetry of large river valleys is associated with it: in the northern hemisphere, many rivers (Dnepr, Volga, etc.) for this reason, the right banks are steep, the left ones are gentle, and vice versa in the southern hemisphere.

With the rotation of the Earth, a natural unit of time is associated - a day, and there is a change of day and night. Days are stellar and sunny. sidereal day is the time interval between two successive upper culminations of the star through the meridian of the observation point. During a sidereal day, the Earth makes a complete revolution around its axis. They are equal to 23 hours 56 minutes 4 seconds. Sidereal days are used in astronomical observations. A true solar day is the time interval between two successive upper culminations of the center of the Sun through the meridian of the observation point. The duration of a true solar day varies throughout the year, primarily due to the uneven movement of the Earth in an elliptical orbit. Hence, they are also inconvenient for measuring time. For practical purposes, the average solar day is used. Mean solar time is measured by the so-called mean Sun - an imaginary point that moves uniformly along the ecliptic and makes a complete revolution per year, like the true Sun. The average solar day is 24 hours. They are longer than stellar ones, since the Earth rotates around its axis in the same direction in which it orbits around the Sun with an angular velocity of about 1 ° per day. Because of this, the Sun moves against the background of the stars, and the Earth still needs to “turn around” by about 1 ° so that the Sun “comes” to the same meridian. Thus, in a solar day, the Earth rotates approximately 361 °. To convert true solar time to mean solar time, a correction is introduced - the so-called equation of time. Its maximum positive value is +14 min on February 11, the largest negative value is -16 min on November 3. The beginning of the average solar day is taken as the moment of the lower climax of the average Sun - midnight. This account of time is called civil time.

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