The fact that the Earth revolves both on its axis and around the Sun, our natural luminary, today there is no doubt in any of the people. This is an absolute and confirmed fact, but why does the Earth rotate exactly the way it does? In this issue, we will figure it out today.
Why does the Earth revolve on its axis
We will start with the very first question, which is the nature of the independent rotation of our planet.
And the answer to this question, as to many other questions about the secrets of our universe, is the Sun. It is the impact of the Sun's rays on our planet that sets it in motion. If we delve a little more into this issue, then it is worth noting that the sun's rays warm up the atmosphere and hydrosphere of the planet, which are set in motion during the heating process. This movement makes the Earth move.
As for the answer to the question why the Earth rotates counterclockwise, and not along it, as such, there is no actual confirmation of this fact. However, it is worth noting that most bodies in our solar system rotate in a counterclockwise direction. That is why this condition also affected our planet.
In addition, it is important to understand that the Earth rotates counterclockwise only on condition that its movement will be observed from the North Pole. In the case of observations from the South Pole, the rotations will occur differently - clockwise.
Why does the earth revolve around the sun
As for a more global issue related to the rotation of our planet around its natural luminary, we considered it in the most detail within the framework of the corresponding article on our website. However, in a nutshell, the reason for this rotation is the law of universal gravitation, which acts in Space as well as on Earth. And it consists in the fact that bodies with a greater mass attract less "weighty" bodies to themselves. Thus, the Earth is attracted to the Sun and rotates around the star due to its mass, as well as acceleration, moving strictly along the existing orbit.
Why does the moon revolve around the earth
We have also already considered the nature of the rotations of the natural satellite of our planet, and the reason for this movement has a similar character - the law of universal gravitation. The Earth, of course, has a more serious mass than the Moon. Accordingly, the Moon is attracted to the Earth and makes motion in its orbit.
For an observer in the Northern Hemisphere, for example, in the European part of Russia, the Sun habitually rises in the east and rises to the south, occupying the highest position in the sky at noon, then tilts to the west and disappears behind the horizon. This movement of the Sun is only visible and is caused by the rotation of the Earth around its axis. If you look at the Earth from above in the direction of the North Pole, then it will rotate counterclockwise. In this case, the sun is in place, the visibility of its movement is created due to the rotation of the Earth.
Earth's annual rotation
Around the Sun, the Earth also rotates counterclockwise: if you look at the planet from above, from the side of the North Pole. Since the earth's axis is tilted relative to the plane of rotation, as the earth rotates around the sun, it illuminates it unevenly. Some areas receive more sunlight, others less. Due to this, the seasons change and the length of the day changes.
Spring and Autumn Equinox
Twice a year, March 21 and September 23, the Sun equally illuminates the Northern and Southern Hemispheres. These moments are known as the autumnal equinox. In March in the Northern Hemisphere it begins, in the Southern - autumn. In September, on the contrary, autumn comes to the Northern Hemisphere, and spring comes to the Southern Hemisphere.
Summer and winter solstice
In the Northern Hemisphere on June 22, the Sun rises highest above the horizon. The day has the longest duration, and the night on this day is the shortest. The winter solstice occurs on December 22nd, with the shortest day and the longest night. In the Southern Hemisphere, the opposite is true.
polar night
Due to the tilt of the earth's axis, the polar and circumpolar regions of the Northern Hemisphere in the winter months are without sunlight - the Sun does not rise above the horizon at all. This phenomenon is known as the polar night. A similar polar night exists for the circumpolar regions of the Southern Hemisphere, the difference between them is exactly six months.
What gives the Earth its rotation around the Sun
The planets cannot but revolve around their stars - otherwise they would simply be attracted and burned up. The uniqueness of the Earth lies in the fact that the inclination of its axis at 23.44 ° turned out to be optimal for the emergence of all the diversity of life on the planet.
It is thanks to the tilt of the axis that the seasons change; there are different climatic zones that provide a variety of terrestrial flora and fauna. A change in the heating of the earth's surface ensures the movement of air masses, and therefore, precipitation in the form of rain and snow.
The distance from the Earth to the Sun of 149.6 million km also turned out to be optimal. A little further, and the water on Earth would be only in the form of ice. A little closer and the temperature would already be too high. The very emergence of life on Earth and the diversity of its forms became possible precisely due to the unique coincidence of such a variety of factors.
Man sees the Earth as flat, but it has long been established that the Earth is a sphere. People agreed to call this celestial body a planet. Where did this name come from?
Ancient Greek astronomers, observing the behavior of celestial bodies, introduced two opposite terms in meaning: planetes asteres - "stars" - celestial bodies, like stars, moving along; asteres aplanis - "fixed stars" - celestial bodies that remained motionless for a year. In the beliefs of the Greeks, the Earth was motionless and was in the center, so they attributed it to the category of "fixed stars". The Greeks knew Mercury, Venus, Mars, Jupiter and Saturn, visible to the naked eye, but they called them not “planets”, but “wandering”. In ancient Rome, astronomers have already called these bodies "planets", replenishing this with the Sun and the Moon. The idea of a seven-planetary system survived until the Middle Ages. In the 16th century, Nicolaus Copernicus turned his eyes on the device, noticing its heliocentricity. The Earth, which was previously considered the center of the world, was reduced to the position of one of the planets revolving around the Sun. In 1543, Copernicus published his work entitled "On the conversions of the heavenly spheres", in which he stated his point of view. Unfortunately, the church did not appreciate the revolutionary nature of Copernicus's views: his sad fate is known. Incidentally, according to Engels, "the liberation of natural science from theology" begins its chronology precisely with the published work of Copernicus. So Copernicus replaced the geocentric system of the world with the heliocentric one. The name "planet" for the Earth was fixed. The definition of the planet, in general, has always been ambiguous. Some astronomers argue that the planet should be massive enough, others consider it an optional condition. If we approach the issue formally, the Earth can be safely called a planet, if only because the word “planet” itself comes from the ancient Greek planis, meaning “mobile,” and modern science has no doubts about the mobility of the Earth.
"And yet, it turns!" - this encyclopedic phrase uttered by the physicist and astronomer of the past Galileo Galilei, we have known since school time. But why does the Earth turn? In fact, this question is very often asked by their parents as small children, and adults themselves are not averse to comprehending the secrets of the Earth's rotation.
For the first time, an Italian scientist spoke in his scientific works that the Earth revolves on its axis at the beginning of the 16th century. But about the fact that rotation is taking place, there has always been a lot of controversy in the scientific community. One of the most widespread theories says that in the process of the earth's rotation, other processes played a major role - those that went on in time immemorial, when only education. Clouds of cosmic dust "knocked together", and thus the "embryos" of planets were formed. Then other cosmic bodies - large and smaller - were "attracted". It is the collision with large celestial ones, according to some scientists, that the constant rotation of the planets is due. And then, according to the theory, by inertia, they continued to rotate. True, if we take this theory into account, many legitimate questions arise. Why are there six planets in the solar system rotating in one direction, and one more - Venus in the opposite direction? Why does the planet Uranus rotate in such a way that the time of day does not change on this planet? Why can the rotation speed of the earth change (insignificantly, of course, but still)? Scientists have yet to answer all these questions. It is known that the Earth tends to slow down its rotation somewhat. Each century, the time for a complete revolution around the axis increases - by approximately 0.0024 seconds. Scientists associate this with the influence of the Earth's satellite - the Moon. Well, about the planets of the solar system, we can say that the planet Venus is considered to be the "slowest" in rotation, and Uranus is the fastest.
Sources:
- The Earth Spins Faster Every Six Years - Naked Science
Hello dear readers! Today I would like to touch on the topic of the Earth and, and I thought that the post on how the Earth rotates will be useful to you 🙂 After all, day and night depend on it, as well as the seasons. Let's take a closer look at everything.
Our planet revolves around its axis and around the Sun. When it makes one revolution around the axis, it takes one day, and when around the Sun - one year. Read more about this in more detail:
Earth axis.
Earth's axis (axis of rotation of the Earth) - this is a straight line around which the Earth's daily rotation occurs; this line passes through the center and crosses the surface of the earth.
The tilt of the axis of rotation of the Earth.
The Earth's axis of rotation is inclined to the plane at an angle of 66 ° 33´; thanks to this it happens. When the Sun is over the Northern Tropic (23 ° 27'N), summer begins in the Northern Hemisphere, while the Earth is at the farthest distance from the Sun.
When the Sun rises over the Southern Tropic (23 ° 27 'S), summer begins in the Southern Hemisphere.
In the Northern Hemisphere, winter begins at this time. The attraction of the Moon, the Sun and other planets does not change the angle of inclination of the earth's axis, but leads to the fact that it moves along a circular cone. This movement is called precession.
The North Pole in our time is directed to the North Star. The Earth's axis over the next 12,000 years, as a result of precession, will pass approximately half way, and will be directed towards the star Vega.
About 25,800 years make up a complete cycle of precession and significantly affects the climatic cycle.
Twice a year, when the Sun is directly above the equator, and twice a month, when the Moon is in a similar position, the attraction due to precession decreases to zero and there is a periodic increase and decrease in the rate of precession.
These wobbling movements of the earth's axis are known as nutation, which peaks every 18.6 years. In terms of the significance of its influence on the climate, this frequency ranks second after changing seasons.
Rotation of the Earth around its axis.
The daily rotation of the Earth - the movement of the Earth counterclockwise, or from west to east, as viewed from the North Pole of the world. The rotation of the Earth determines the length of the day and causes the change of day and night.
The Earth makes one revolution around its axis in 23 hours 56 minutes and 4.09 seconds. During the period of one revolution around the Sun, the Earth makes approximately 365 ¼ revolutions, this is one year or equal to 365 ¼ days.
Every four years one more day is added to the calendar, because for each such turn, in addition to a whole day, another quarter of a day is spent. The rotation of the Earth gradually slows down the gravitational pull of the Moon, and lengthens the day by about 1/1000 s every century.
Judging by the geological data, the rate of rotation of the Earth could change, but by no more than 5%.
Around the Sun, the Earth rotates in an elliptical orbit, close to circular, at a speed of about 107,000 km / h in the direction from west to east. The average distance to the Sun is 149,598 thousand km, and the difference between the smallest and largest distances is 4.8 million km.
The eccentricity (deviation from the circle) of the earth's orbit changes slightly over a cycle of 94 thousand years. It is believed that the formation of a complex climatic cycle is facilitated by changes in the distance to the Sun, and the onset and departure of glaciers during ice ages are associated with its individual stages.
Everything in our vast Universe is very complex and precise. And our Earth is just a point in it, but this is our native home, which we learned a little more about from the post about how the Earth rotates. See you in new posts about the study of the Earth and the Universe🙂
Our planet is constantly in motion:
- rotation around its own axis, movement around the sun;
- rotation with the Sun around the center of our galaxy;
- motion relative to the center of the Local Group of Galaxies and others.
The movement of the earth around its own axis
Rotation of the Earth around its axis(fig. 1). An imaginary line around which it revolves is taken as the earth's axis. This axis is tilted 23 ° 27 "from the perpendicular to the plane of the ecliptic. The earth's axis intersects with the earth's surface at two points - the poles - North and South. When viewed from the North Pole, the Earth's rotation occurs counterclockwise or, as is commonly believed, with from west to east The planet makes a complete revolution around its axis in one day.
Rice. 1. Rotation of the Earth around its axis
Day is a unit of time. There are stellar and sunny days.
Stellar day- this is the period of time during which the Earth turns on its axis in relation to the stars. They are equal to 23 hours 56 minutes 4 seconds.
Sunny day- this is the period of time during which the Earth turns on its axis in relation to the Sun.
The angle of rotation of our planet around its axis is the same at all latitudes. In one hour, each point on the Earth's surface moves 15 ° from its original position. But at the same time, the speed of movement is inversely proportional to the geographical latitude: at the equator it is equal to 464 m / s, and at a latitude of 65 ° it is only 195 m / s.
The rotation of the Earth around its axis in 1851 was proved in his experiment by J. Foucault. In Paris, in the Pantheon, a pendulum was hung under a dome, and a circle with divisions was hung under it. With each subsequent movement, the pendulum found itself on new divisions. This can only happen if the Earth's surface rotates under the pendulum. The position of the swinging plane of the pendulum at the equator does not change, because the plane coincides with the meridian. The axial rotation of the Earth has important geographic implications.
When the Earth rotates, centrifugal force arises, which plays an important role in shaping the shape of the planet and reduces the force of gravity.
Another of the most important consequences of axial rotation is the formation of a rotational force - Coriolis forces. In the XIX century. it was first calculated by a French scientist in the field of mechanics G. Coriolis (1792-1843)... This is one of the inertial forces introduced to take into account the influence of the rotation of a moving frame of reference on the relative motion of a material point. Its effect can be briefly expressed as follows: every moving body in the Northern Hemisphere deviates to the right, and in the Southern Hemisphere - to the left. At the equator, the Coriolis force is zero (Fig. 3).
Rice. 3. Action of the Coriolis force
The action of the Coriolis force extends to many phenomena in the geographic envelope. Its deflecting effect is especially noticeable in the direction of movement of air masses. Under the influence of the deflecting force of the Earth's rotation, the winds of the temperate latitudes of both hemispheres assume a predominantly westerly direction, and in tropical latitudes - easterly. A similar manifestation of the Coriolis force is found in the direction of movement of oceanic waters. The asymmetry of river valleys is also associated with this force (the right bank is usually high in the Northern Hemisphere, in the South - the left).
The rotation of the Earth around its axis also leads to the movement of solar illumination along the earth's surface from east to west, i.e., to the change of day and night.
The change of day and night creates a daily rhythm in living and inanimate nature. The daily rhythm is closely related to light and temperature conditions. The diurnal variation of temperature, day and night breezes, etc. are well known. Diurnal rhythms also occur in wildlife - photosynthesis is possible only during the day, most plants open their flowers at different hours; some animals are active during the day, others at night. Human life also proceeds in a daily rhythm.
Another consequence of the rotation of the Earth around its axis is the difference in time at different points on our planet.
Since 1884, the zone counting of time was adopted, that is, the entire surface of the Earth was divided into 24 time zones, 15 ° each. Per standard time take the local time of the middle meridian of each belt. The times for neighboring time zones differ by one hour. The boundaries of the belts are drawn taking into account the political, administrative and economic boundaries.
The zero belt is considered to be Greenwich (after the name of the Greenwich Observatory near London), which runs on both sides of the prime meridian. The time of the zero, or initial, meridian is considered World time.
Meridian 180 ° is accepted as international date line- a conditional line on the surface of the globe, on both sides of which the hours and minutes coincide, and the calendar dates differ by one day.
For a more rational use of daylight in the summer in 1930 in our country was introduced daylight saving time, advancing the zone one by one hour. For this, the hands of the clock were moved forward one hour. In this regard, Moscow, being in the second time zone, lives according to the time of the third time zone.
Since 1981, in the period from April to October, the time has been shifted forward one hour. This is the so-called summer time. It is introduced to save energy. In summer, Moscow is two hours ahead of standard time.
The time of the time zone in which Moscow is located is Moscow.
The movement of the earth around the sun
Rotating around its axis, the Earth simultaneously moves around the Sun, going around the circle in 365 days 5 hours 48 minutes 46 seconds. This period is called astronomical year. For convenience, it is assumed that there are 365 days in a year, and every four years, when out of six hours 24 hours are "accumulated", there are not 365, but 366 days in a year. This year is called leap, and one day is added to February.
The path in space along which the Earth moves around the Sun is called orbit(fig. 4). The Earth's orbit is elliptical, so the distance from the Earth to the Sun is not constant. When the Earth is in perihelion(from the Greek. peri- near, near and helios- Sun) - the point of the orbit closest to the Sun - on January 3, the distance is 147 million km. It is winter in the Northern Hemisphere at this time. The farthest distance from the Sun at aphelion(from the Greek. aro- away from and helios- Sun) - the greatest distance from the Sun - July 5. It is equal to 152 million km. At this time, it is summer in the Northern Hemisphere.
Rice. 4. The movement of the Earth around the Sun
The annual movement of the Earth around the Sun is observed by the continuous change in the position of the Sun in the sky - the midday height of the Sun and the position of its rising and setting change, the duration of the light and dark parts of the day changes.
When moving in orbit, the direction of the earth's axis does not change, it is always directed towards the North Star.
As a result of a change in the distance from the Earth to the Sun, as well as due to the tilt of the Earth's axis to the plane of its motion around the Sun on the Earth, an uneven distribution of solar radiation is observed throughout the year. This is how the seasons change, which is characteristic of all planets, for which the inclination of the axis of rotation to the plane of its orbit (ecliptic) differs from 90 °. The planet's orbital speed in the Northern Hemisphere is higher in winter and less in summer. Therefore, the winter half-year lasts 179, and the summer one - 186 days.
As a result of the movement of the Earth around the Sun and the inclination of the Earth's axis to the plane of its orbit by 66.5 ° on our planet, there is not only a change in the seasons, but also a change in the length of the day and night.
The rotation of the Earth around the Sun and the change of seasons on Earth are shown in Fig. 81 (days of equinox and solstice according to the seasons in the Northern Hemisphere).
Only twice a year - on the days of the equinox, the duration of the day and night on the whole Earth is practically the same.
Equinox- the moment in time at which the center of the Sun, with its apparent annual movement along the ecliptic, crosses the celestial equator. There are spring and autumn equinoxes.
The tilt of the Earth's axis of rotation around the Sun on the days of the equinoxes on March 20-21 and September 22-23 turns out to be neutral with respect to the Sun, and the parts of the planet facing it are uniformly illuminated from pole to pole (Fig. 5). The sun's rays fall steeply at the equator.
The longest day and the shortest night are observed on the summer solstice.
Rice. 5. Illumination of the Earth by the Sun on the days of the equinox
Solstice- the moment the center of the Sun passes the ecliptic points farthest from the equator (solstice points). Distinguish between summer and winter solstices.
On the summer solstice, June 21-22, the Earth is in such a position in which the northern end of its axis is tilted towards the Sun. And the rays fall vertically not on the equator, but on the northern tropic, the latitude of which is 23 ° 27 "All day long, not only the polar regions are illuminated, but also the space beyond them up to latitude 66 ° 33" (Arctic Circle). In the Southern Hemisphere at this time, only that part of it that lies between the equator and the southern Arctic Circle (66 ° 33 ") is illuminated. Behind it on this day, the earth's surface is not illuminated.
On the winter solstice, December 21-22, everything happens the other way around (Fig. 6). The sun's rays are already falling steeply on the southern tropic. Illuminated in the Southern Hemisphere are areas that lie not only between the equator and the tropic, but also around the South Pole. This situation continues until the day of the vernal equinox.
Rice. 6. Illumination of the Earth on the day of the winter solstice
On two parallels of the Earth on the solstice days, the Sun at noon is directly above the observer's head, that is, at the zenith. Such parallels are called the tropics. In the Northern Tropic (23 ° N), the Sun is at its zenith on June 22, in the Southern Tropic (23 ° S) on December 22.
At the equator, day is always equal to night. The angle of incidence of sunlight on the earth's surface and the length of the day there change little, so the change of seasons is not pronounced.
Polar circles are remarkable in that they are the boundaries of areas where there are polar days and nights.
Polar day- the period when the Sun does not descend below the horizon. The further from the Arctic Circle near the pole, the longer the polar day. At the latitude of the Arctic Circle (66.5 °), it lasts only one day, and at the Pole - 189 days. In the Northern Hemisphere at the latitude of the Arctic Circle, the polar day is observed on June 22 - the day of the summer solstice, and in the Southern Hemisphere at the latitude of the Southern Arctic Circle - on December 22.
polar night lasts from one day at the latitude of the Arctic Circle to 176 days at the poles. During the polar night, the Sun does not appear above the horizon. In the Northern Hemisphere at the latitude of the Arctic Circle, this phenomenon is observed on December 22.
It is impossible not to note such a wonderful natural phenomenon as the white nights. White Nights- these are bright nights at the beginning of summer, when the evening dawn converges with the morning and twilight lasts all night. They are observed in both hemispheres at latitudes exceeding 60 °, when the center of the Sun at midnight drops below the horizon by no more than 7 °. In St. Petersburg (about 60 ° N), white nights last from June 11 to July 2, in Arkhangelsk (64 ° N) - from May 13 to July 30.
The seasonal rhythm in connection with the annual movement primarily affects the illumination of the earth's surface. Depending on the change in the height of the Sun above the horizon, there are five light belts. The hot belt lies between the North and South tropics (the Tropic of Cancer and the Tropic of Capricorn), occupies 40% of the earth's surface and is distinguished by the largest amount of heat coming from the Sun. Between the tropics and the Arctic Circle in the Southern and Northern Hemispheres, there are moderate light belts. The seasons of the year are already expressed here: the farther from the tropics, the shorter and cooler the summer, the longer and colder the winter. The polar belts in the Northern and Southern Hemispheres are bounded by the Arctic Circle. Here, the height of the Sun above the horizon is low throughout the year, so the amount of solar heat is minimal. The polar belts are characterized by polar days and nights.
Depending on the annual movement of the Earth around the Sun, there are not only the change of seasons and the associated irregularity of the illumination of the earth's surface in latitudes, but also a significant part of the processes in the geographic envelope: seasonal changes in the weather, the regime of rivers and lakes, rhythm in the life of plants and animals, types and terms of agricultural work.
Calendar.Calendar- a system for calculating long periods of time. This system is based on periodic natural phenomena associated with the movement of heavenly bodies. The calendar uses astronomical phenomena - the change of seasons, day and night, the change in lunar phases. The first calendar was Egyptian, created in the 4th century. BC NS. On January 1, 45, Julius Caesar introduced the Julian calendar, which is still used by the Russian Orthodox Church. Due to the fact that the duration of the Julian year is 11 min 14 s longer than the astronomical one, by the 16th century. the "error" accumulated in 10 days - the day of the vernal equinox did not come on March 21, but on March 11. This mistake was corrected in 1582 by the decree of Pope Gregory XIII. The counting of days was moved 10 days ahead, and the day after October 4 was prescribed to be considered Friday, but not October 5, but October 15. The vernal equinox was again returned to March 21, and the calendar was called Gregorian. It was introduced in Russia in 1918. However, it also has a number of disadvantages: unequal length of months (28, 29, 30, 31 days), inequality of quarters (90, 91, 92 days), inconsistency of the numbers of months by days of the week.
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Rotation of the Earth around its axis
The Earth rotates around an axis from west to east, i.e. counterclockwise, if you look at the Earth from the North Star (from the North Pole). In this case, the angular speed of rotation, that is, the angle by which any point on the surface of the Earth rotates, is the same and amounts to 15 ° per hour. Linear velocity depends on latitude: at the equator it is greatest - 464 m / s, and the geographic poles are stationary.
The main physical proof of the Earth's rotation around its axis is the experiment with Foucault's swinging pendulum. After the French physicist J. Foucault V. in the Parisian Pantheon carried out his famous experiment, the rotation of the Earth around its axis has become an immutable truth.
Physical evidence of the Earth's axial rotation is also the measurements of the 1 ° meridian arc, which is at the equator and 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 their preservation by inertia of a greater linear velocity of point A (at a height) in comparison with point B (near the earth's surface). When falling, objects are deflected to the east on the Earth because it rotates from west to east. The deviation is greatest at the equator. At the poles, bodies fall vertically without deviating from the direction of the earth's axis.
The geographic significance of the axial rotation of the Earth is extremely high. First of all, it affects the shape of the Earth. The compression of the Earth at the poles is the result of its axial rotation. Earlier, when the Earth rotated at a higher angular velocity, the polar contraction was more significant. The lengthening of the day and, as a consequence, the decrease in the equatorial radius and the increase in the polar one are accompanied by tectonic deformations of the earth's crust (faults, folds) and the restructuring of the Earth's macro-relief.
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 inertial forces called the Coriolis acceleration in honor of the French scientist who first explained this phenomenon).
According to the law of inertia, each moving body seeks to keep the direction and speed of its movement in world space unchanged.
Deviation is the result of the body participating 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. The deviation increases towards the poles and becomes the 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- Coriolis force, m Is the mass of a moving body, w- angular velocity, v- the speed of a moving body, j- geographic latitude. The manifestation of the Coriolis force in natural processes is very diverse. It is because of it that eddies of various scales arise in the atmosphere, including cyclones and anticyclones, winds and sea currents deviate from the gradient direction, influencing the climate and, through it, on natural zonality and regionality; it is associated with the asymmetry of large river valleys: in the northern hemisphere, many rivers (Dnieper, Volga, etc.) for this reason, the right banks are steep, the left ones are gentle, and in the southern hemisphere it is vice versa.
The natural unit of time is associated with the rotation of the Earth - a day, and there is a change of day and night. The day is starry and sunny. Sidereal day - the time interval between two successive upper climaxes of a star across the meridian of the observation point. For 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 for astronomical observations. A true solar day is the time interval between two successive upper climaxes of the center of the Sun through the meridian of the observation point. The duration of true solar days varies throughout the year primarily due to the uneven motion of the Earth in an elliptical orbit. Hence, they are also inconvenient for measuring time. For practical purposes, average sunny days are used. Average solar time is measured by the so-called average sun - an imaginary point that moves uniformly along the ecliptic and makes a full revolution per year, like the true sun. Average solar days are 24 hours. They are longer than stellar days, since the Earth rotates around its axis in the same direction in which it orbits the Sun with an angular velocity of about 1 ° per day. Because of this, the Sun shifts against the background of the stars, and the Earth still needs to "turn around" by about 1 ° in order for the Sun to "come" to the same meridian. Thus, for a solar day, the Earth makes a revolution by about 361 °. To convert true solar time into mean solar time, an amendment is introduced - the so-called equation of time.
Its maximum positive value is +14 minutes on February 11, the largest negative value is -16 minutes on November 3. The beginning of the average solar day is taken to be the moment of the lower climax of the average Sun - midnight. This time count is called civil time.
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When viewed from the North Pole, the Earth rotates counterclockwise, and if viewed from the South Pole, it rotates clockwise. And the Earth (like all the planets of the solar system, except Venus) rotates around its axis counterclockwise. The snail's house spins clockwise from the center (i.e., it rotates in a counterclockwise direction). What else is spinning, spinning? When one cat sees sparrows (these are her favorite birds), the tail turns clockwise, and if these are not sparrows, but other birds, then it turns counterclockwise.
Therefore, experimental evidence of the Earth's rotation is reduced to the proof of the existence of these two inertial forces in the associated frame of reference. This effect should be most clearly expressed at the poles, where the period of complete rotation of the pendulum plane is equal to the period of the Earth's rotation around the axis (sidereal day).
There are a number of other experiments with pendulums used to prove the rotation of the Earth. The first such experiment was carried out by Hagen in 1910: two weights on a smooth crossbar were installed motionlessly relative to the surface of the Earth. Then the distance between the weights was reduced.
There are a number of other experimental demonstrations of the Earth's diurnal rotation. In general, the reason for the precession and nutation of the Earth is its non-sphericity and the mismatch of the planes of the equator and the ecliptic.
As a result of the gravitational attraction by the Moon and the Sun of the equatorial thickening of the Earth, a moment of forces arises that tends to combine the planes of the equator and the ecliptic.
The explanation of the diurnal rotation of the firmament by the rotation of the Earth around its axis was first proposed by representatives of the Pythagorean school, the Syracusans Giketus and Ekfant. About a century later, the assumption of the Earth's rotation became an integral part of the first heliocentric system of the world, proposed by the great astronomer Aristarchus of Samos (3rd century BC).
The fact that the idea of the daily rotation of the Earth had its supporters back in the 1st century AD. e., evidenced by some statements of the philosophers Seneca, Derkillides, astronomer Claudius Ptolemy.
Clockwise or counterclockwise?
One of Ptolemy's arguments in favor of the immobility of the Earth is the verticality of the trajectories of falling bodies, as in Aristotle. From the work of Ptolemy it follows that the supporters of the hypothesis of the rotation of the Earth to these arguments answered that both the air and all earthly objects move together with the Earth.
At the same time, however, he rejected one of Varahamihira's arguments: in his opinion, even if the Earth rotated, objects could not be torn off from it due to their gravity. The possibility of the Earth's rotation was considered by many scientists of the Muslim East. However, the role of air in this was no longer considered fundamental: not only air, but all objects are carried by the rotating Earth.
A special position in these disputes was taken by the third director of the Samarkand Observatory, Alauddin Ali al-Kushchi (15th century), who rejected the philosophy of Aristotle and considered the rotation of the Earth to be physically possible.
In his opinion, astronomers and philosophers have not presented sufficient evidence to refute the rotation of the Earth. Buridan and Orem justly disagreed with this, according to which celestial phenomena should occur in the same way regardless of whether the Earth or the Cosmos rotates. If the Earth rotates, then the arrow flies vertically upwards and at the same time moves to the east, being captured by the air rotating with the Earth.
The main movements of the Earth in space.
Nevertheless, Orem's final verdict on the possibility of the Earth's rotation was negative. Thus, the main role in the unobservability of the Earth's rotation is played by the entrainment of air by its rotation. When refuting the arguments of opponents of the hypothesis of the rotation of the Earth, Bruno also used the theory of impetus. He also predicted that due to the action of centrifugal force, the Earth should be flattened at the poles. A number of objections to the rotation of the Earth were associated with its contradictions with the text of the Holy Scriptures.
I was interested in the topic of what rotates clockwise and what rotates counterclockwise, and that's what I discovered.
In this case, the axial rotation of the Earth was hit, since the movement of the Sun from east to west is part of the daily rotation of the sky. Since the command to stop was given to the Sun, not the Earth, it was concluded from this that it is the Sun that makes the diurnal motion. You have set the earth on solid foundations: it will not shake forever and ever. Supporters of the Earth's rotation (in particular, Giordano Bruno, Johannes Kepler and especially Galileo Galilei) defended in several directions.
See what "EARTH ROTATION" is in other dictionaries:
What is this news? " In the end they would think him a fool, and he really would be a fool. These arguments were considered unconvincing by the Catholic Church, and in 1616 the doctrine of the rotation of the earth was prohibited, and in 1631 it was forbidden.
Galileo was convicted by the Inquisition for his defense. It should be added that religious arguments against the movement of the Earth were brought not only by church leaders, but also by scientists (for example, Tycho Brahe).
Annual movement of the Earth.
According to the law of right-hand traffic, adopted in our country, the circular movement goes counterclockwise. That is, in some countries, helicopters are made with a clockwise rotating propeller, and in others - counterclockwise.
Flocks of bats, flying out of caves, usually form a "dextrorotatory" vortex. But in caves near Karlovy Vary (Czech Republic), for some reason, they spin in a spiral, twisted counterclockwise ... But the dog, before going on business, must spin counterclockwise. The spiral staircases in the castles were twisted clockwise (if viewed from below, and if viewed from above, then counterclockwise) - so that it would be inconvenient for the attackers to attack when they climbed.
