Today no one has any doubts about the fact that the Earth rotates both around its axis and around the Sun, our natural luminary. This is an absolute and proven fact, but why does the Earth spin the way it does? We will look into this issue today.

Why does the Earth spin 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, like 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 deeper into this issue, it is worth noting that the sun's rays warm the atmosphere and hydrosphere of the planet, which are set in motion during the heating process. This movement is what makes the Earth move.

As for the answer to the question of why the Earth rotates counterclockwise and not clockwise, there is no factual confirmation of this fact as such. However, it is worth noting that most bodies in our solar system rotate precisely 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 if its movement is observed from the north pole. In the case of observations from the south pole, rotations will occur differently - clockwise.

Why does the Earth revolve around the Sun

As for the more global issue related to the rotation of our planet around its natural star, we examined it in as much detail as possible within the framework of the corresponding article on our website. However, in short, the reason for this rotation is the law universal gravity, which acts in Space as on Earth. And it lies in the fact that bodies with greater mass attract less “weighty” bodies. 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 rotation of the natural satellite of our planet, and the reason for such movement is of a similar nature - the law of universal gravitation. The Earth, of course, has more mass than the Moon. Accordingly, the Moon is attracted to the Earth and moves along its orbit.

Basic movements of the Earth in space

© Vladimir Kalanov,
website"Knowledge is power".

Our planet rotates around its own axis from west to east, that is, counterclockwise (when viewed from the North Pole). An axis is a conventional straight line crossing the globe in the region of the North and South Poles, that is, the poles have a fixed position and “do not participate” in rotational motion, while all other location points on the earth’s surface rotate, and the linear speed of rotation is surfaces globe depends on the position relative to the equator - the closer to the equator, the higher the linear speed of rotation (let us explain that the angular speed of rotation of any ball is the same at its various points and is measured in rad/sec, we are discussing the speed of movement of an object located on the surface of the Earth and it is higher, the further the object is removed from the axis of rotation).

For example, at the mid-latitudes of Italy the rotation speed is approximately 1200 km/h, at the equator it is maximum and amounts to 1670 km/h, while at the poles it is zero. The consequences of the Earth's rotation around its axis are the change of day and night and the apparent movement of the celestial sphere.

Indeed, it seems that the stars and other celestial bodies of the night sky are moving in the opposite direction to our movement with the planet (that is, from east to west). It seems that the stars are around the North Star, which is located on an imaginary line - a continuation of the earth's axis in a northerly direction. The movement of the stars is not proof that the Earth rotates around its axis, because this movement could be a consequence of the rotation of the celestial sphere, if we assume that the planet occupies a fixed, motionless position in space, as was previously thought.

Day. What are sidereal and solar days?

A day is the length of time during which the Earth makes a complete revolution around its own axis. There are two definitions of the concept “day”. A “solar day” is a period of time for the Earth’s rotation, in which the Sun is taken as the starting point. Another concept is “sidereal day” (from lat. sidus- Genitive sideris- star, celestial body) - implies another starting point - a “fixed” star, the distance to which tends to infinity, and therefore we assume that its rays are mutually parallel. The length of the two types of days differs from each other. A sidereal day is 23 hours 56 minutes 4 seconds, while the duration of a solar day is slightly longer and is equal to 24 hours. The difference is due to the fact that the Earth, rotating around its own axis, also performs an orbital rotation around the Sun. It's easier to figure this out with the help of a drawing.

Solar and sidereal days. Explanation.

Let's consider two positions (see figure) that the Earth occupies when moving along its orbit around the Sun, “ A" - the observer's place on the earth's surface. 1 - the position that the Earth occupies (at the beginning of the countdown of the day) either from the Sun or from any star, which we define as the reference point. 2 - the position of our planet after completing a revolution around its own axis relative to this star: the light of this star, and it is located at a great distance, will reach us parallel to the direction 1 . When the Earth takes its position 2 , we can talk about “sidereal days”, because The Earth has made a full revolution around its axis relative to the distant star, but not yet relative to the Sun. The direction of observing the Sun has changed somewhat due to the rotation of the Earth. In order for the Earth to make a complete revolution around its own axis relative to the Sun (“ sunny day"), you need to wait until it “turns” about 1° more (the equivalent of the Earth moving at an angle every day - it travels 360° in 365 days), this will take just about four minutes.

In principle, the duration of a solar day (although it is taken to be 24 hours) is not a constant value. This is due to the fact that the Earth's orbital movement actually occurs at a variable speed. When the Earth is closer to the Sun, its orbital speed is higher; as it moves away from the sun, the speed decreases. In this regard, a concept such as "average solar day", precisely their duration is twenty-four hours.

In addition, it has now been reliably established that the period of rotation of the Earth increases under the influence of the changing tides caused by the Moon. The slowdown is approximately 0.002 s per century. The accumulation of such, at first glance, imperceptible deviations means, however, that from the beginning of our era to today the total slowdown is already about 3.5 hours.

Revolution around the Sun is the second main movement of our planet. The Earth moves in an elliptical orbit, i.e. the orbit has the shape of an ellipse. When the Moon is in close proximity to the Earth and falls into its shadow, eclipses occur. The average distance between the Earth and the Sun is approximately 149.6 million kilometers. In astronomy, the unit used to measure distances within solar system; they call her "astronomical unit" (a.e.). The speed at which the Earth moves in orbit is approximately 107,000 km/h. The angle formed by the earth's axis and the plane of the ellipse is approximately 66°33", and is maintained throughout the entire orbit.

From the point of view of an observer on Earth, the revolution results in the apparent movement of the Sun along the ecliptic through the stars and constellations represented in the Zodiac. In fact, the Sun also passes through the constellation Ophiuchus, but it does not belong to the Zodiac circle.

Seasons

The change of seasons is a consequence of the Earth's revolution around the Sun. The reason for seasonal changes is the inclination of the Earth's rotation axis to the plane of its orbit. Moving along an elliptical orbit, the Earth in January is at the point closest to the Sun (perihelion), and in July at the point farthest from it - aphelion. The reason for the change of seasons is the inclination of the orbit, as a result of which the Earth tilts towards the Sun with one hemisphere and then the other and, accordingly, receives a different amount of sunlight. In summer, the Sun reaches the highest point of the ecliptic. This means that the Sun makes its longest movement over the horizon during the day, and the length of the day is maximum. In winter, on the contrary, the Sun is low above the horizon, the sun's rays fall on the Earth not directly, but obliquely. The day length is short.

Depending on the time of year, different parts of the planet are exposed to the sun's rays. The rays are perpendicular to the tropics during the solstice.

Seasons in the Northern Hemisphere

Annual movement of the Earth

Determining the year, the basic calendar unit of time, is not as simple as it seems at first glance, and depends on the chosen reference system.

The time interval during which our planet completes its orbit around the Sun is called a year. However, the length of the year varies depending on whether the starting point is taken to measure it infinitely distant star or Sun.

In the first case we mean « sidereal year"("sidereal year") . It is equal 365 days 6 hours 9 minutes and 10 seconds and represents the time required for the Earth to completely revolve around the Sun.

But if we measure the time required for the Sun to return to the same point in the celestial coordinate system, for example, at the vernal equinox, then we get the duration "solar year" 365 days 5 hours 48 minutes 46 seconds. The difference between the sidereal and solar years occurs due to the precession of the equinoxes; every year the equinoxes (and, accordingly, the sun stations) come “earlier” by approximately 20 minutes. compared to the previous year. Thus, the Earth moves around its orbit a little faster than the Sun, in its apparent movement through the stars, returns to the vernal equinox.

Considering that the duration of the seasons is in close connection with the Sun, when compiling calendars, it is taken as a basis "solar year" .

Also in astronomy, instead of the usual astronomical time, determined by the period of rotation of the Earth relative to the stars, a new uniformly flowing time, not related to the rotation of the Earth and called ephemeris time, was introduced.

Read more about ephemeris time in the section: .

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Our planet is in constant motion, it rotates around the Sun and its own axis. The Earth's axis is an imaginary line drawn from the North to the South Pole (they remain motionless during rotation) at an angle of 66 0 33 ꞌ relative to the plane of the Earth. People cannot notice the moment of rotation, because all objects move in parallel, their speed is the same. It would look exactly the same as if we were sailing on a ship and did not notice the movement of objects and objects on it.

A full revolution around the axis is completed within one sidereal day, consisting of 23 hours 56 minutes and 4 seconds. During this period, first one or the other side of the planet turns towards the Sun, receiving different amounts of heat and light from it. In addition, the rotation of the Earth around its axis affects its shape (flattened poles are the result of the planet’s rotation around its axis) and the deviation when bodies move in the horizontal plane (rivers, currents and winds of the Southern Hemisphere deviate to the left, of the Northern Hemisphere to the right).

Linear and angular rotation speed

(Earth Rotation)

The linear speed of rotation of the Earth around its axis is 465 m/s or 1674 km/h in the equator zone; as you move away from it, the speed gradually slows down, in the North and South Poles it is equal to zero. For example, for citizens of the equatorial city of Quito (the capital of Ecuador in South America) the rotation speed is just 465 m/s, and for Muscovites living on the 55th parallel north of the equator, it is 260 m/s (almost half as much).

Every year, the speed of rotation around the axis decreases by 4 milliseconds, which is due to the influence of the Moon on the strength of sea and ocean tides. The Moon's gravity "pulls" the water in the opposite direction to the Earth's axial rotation, creating a slight frictional force that slows the rotation speed by 4 milliseconds. The speed of angular rotation remains the same everywhere, its value is 15 degrees per hour.

Why does day give way to night?

(The change of night and day)

The time for a complete revolution of the Earth around its axis is one sidereal day (23 hours 56 minutes 4 seconds), during this time period the side illuminated by the Sun is first “in the power” of the day, the shadow side is under the control of the night, and then vice versa.

If the Earth rotated differently and one side of it was constantly turned towards the Sun, then there would be heat(up to 100 degrees Celsius) and all the water would have evaporated; on the other side, on the contrary, frosts would have raged and the water would have been under a thick layer of ice. Both the first and second conditions would be unacceptable for the development of life and the existence of the human species.

Why do the seasons change?

(Change of seasons on Earth)

Due to the fact that the axis is inclined relative to the earth's surface at a certain angle, its sections receive different time varying amounts of heat and light, which causes the seasons to change. According to the astronomical parameters necessary to determine the time of year, certain points in time are taken as reference points: for summer and winter these are the Solstice Days (June 21 and December 22), for spring and autumn - the Equinoxes (March 20 and September 23). From September to March, the Northern Hemisphere faces the Sun for less time and, accordingly, receives less heat and light, hello winter-winter, the Southern Hemisphere at this time receives a lot of heat and light, long live summer! 6 months pass and the Earth moves to the opposite point of its orbit and the Northern Hemisphere receives more heat and light, the days become longer, the Sun rises higher - summer comes.

If the Earth were located in relation to the Sun in an exclusively vertical position, then the seasons would not exist at all, because all points on the half illuminated by the Sun would receive the same and uniform amount of heat and light.

We all know that the Earth revolves around the Sun. Based on this, a logical question arises: does the Sun itself rotate? And if so, around what? Astronomers received an answer to this question only in the 20th century.

Our star really moves, and if the Earth has two circles of rotation (around the Sun and around its axis), then the Sun has three. Moreover, the entire solar system, along with the planets and other cosmic bodies, is gradually moving away from the center of the galaxy, shifting several million kilometers with each revolution.

What does the Sun move around?

What does the Sun revolve around? It is known that our star is located, the diameter of which is about 30,000 parsecs. A parsec is an astronomical unit of measurement equal to 3.26 light years.

In the central part of the Milky Way there is a relatively small Galactic center with a radius of about 1000 parsecs. Star formation still occurs in it and the core is located, thanks to which our star system once arose.

The distance of the Sun from the Galactic center is 26 thousand light years, that is, it is located closer to the edges of the galaxy. Together with the rest of the stars included in Milky Way, The sun revolves around this center. Its average speed varies from 220 to 240 km per second.


One revolution around the central part of the galaxy takes an average of 200 million years. Over the entire period of its existence, our planet, together with the Sun, orbited the Galactic core only about 30 times.

Why does the Sun revolve around the galaxy?

As with the rotation of the Earth, the exact cause of the movement of the Sun has not been established. According to one version, there is some kind of dark matter (supermassive black hole) in the Galactic center, which affects both the rotation of stars and their speed. Around this hole there is another hole of smaller mass.

Together, both matters exert a gravitational influence on the stars in the galaxy and force them to move along different trajectories. Other scientists are of the opinion that the movement is due to gravitational forces emanating from the core of the Milky Way.

Like any object, the Sun moves by inertia along a straight path, but the gravity of the Galactic Center attracts it to itself and thereby makes it rotate in a circle.

Does the Sun rotate on its axis?

The rotation of the Sun around its axis is the second circle of its movement. Since it consists of gases, its movement occurs differentially.


In other words, the star rotates faster at its equator, and slower at its poles. Tracking the rotation of the Sun around its axis is quite difficult, so scientists have to navigate by sunspots.

On average, a spot in the region of the solar equator rotates around the axis of the Sun and returns to its original position in 24.47 days. Regions at the poles move around the solar axis every 38 days.

To calculate a specific value, scientists decided to focus on the position 26° from the equator, since approximately in this place it is observed greatest number sunspots. As a result, astronomers came to a single figure, according to which the speed of revolution of the Sun around its own axis is 25.38 days.

What is rotation about a balanced center?

As mentioned above, unlike the Earth, the Sun has three planes of rotation. The first is around the center of the galaxy, the second is around its axis, but the third is the so-called gravitational balanced center. If you explain in simple words, then all the planets revolving around the Sun, although they have much less mass, still attract it a little towards themselves.

As a result of these processes, the Sun's own axis also rotates in space. As it rotates, it describes the radius of the central balancing, within which the Sun rotates. At the same time, the Sun itself also describes its radius. The general picture of this movement is quite clear to astronomers, but its practical component has not been fully studied.


In general, our star is a very complex and multifaceted system, so in the future scientists will have to uncover many more of its secrets and mysteries.

The earth is always in motion. Although we seem to be standing motionless on the surface of the planet, it continuously rotates around its axis and the Sun. This movement is not felt by us, as it resembles flying in an airplane. We're moving at the same speed as the plane, so we don't feel like we're moving at all.

At what speed does the Earth rotate around its axis?

The Earth rotates once on its axis in almost 24 hours (to be precise, in 23 hours 56 minutes 4.09 seconds or 23.93 hours). Since the Earth's circumference is 40,075 km, any object at the equator rotates at a speed of approximately 1,674 km per hour or approximately 465 meters (0.465 km) per second (40075 km divided by 23.93 hours and we get 1674 km per hour).

At (90 degrees north latitude) and (90 degrees south latitude), the speed is effectively zero because the pole points rotate at a very slow speed.

To determine the speed at any other latitude, simply multiply the cosine of the latitude by the planet's rotation speed at the equator (1674 km per hour). The cosine of 45 degrees is 0.7071, so multiply 0.7071 by 1674 km per hour and get 1183.7 km per hour.

The cosine of the required latitude can be easily determined using a calculator or looked at in the cosine table.

Earth rotation speed for other latitudes:

• 10 degrees: 0.9848×1674=1648.6 km per hour;
• 20 degrees: 0.9397×1674=1573.1 km per hour;
• 30 degrees: 0.866×1674=1449.7 km per hour;
• 40 degrees: 0.766×1674=1282.3 km per hour;
• 50 degrees: 0.6428×1674=1076.0 km per hour;
• 60 degrees: 0.5×1674=837.0 km per hour;
• 70 degrees: 0.342×1674=572.5 km per hour;
• 80 degrees: 0.1736×1674=290.6 km per hour.

Cyclic braking

Everything is cyclical, even the speed of rotation of our planet, which geophysicists can measure with millisecond accuracy. The Earth's rotation typically has five-year cycles of deceleration and acceleration, and Last year The slowdown cycle is often associated with a surge in earthquakes around the world.

Since 2018 is the latest in the slowdown cycle, scientists expect an increase in seismic activity this year. Correlation is not causation, but geologists are always looking for tools to try to predict when the next big earthquake will happen.

Oscillations of the earth's axis

The Earth rotates slightly as its axis drifts toward the poles. The drift of the Earth's axis has been observed to accelerate since 2000, moving eastward at a rate of 17 cm per year. Scientists have determined that the axis is still moving east instead of moving back and forth due to the combined effect of the melting of Greenland and , as well as the loss of water in Eurasia.

Axial drift is expected to be particularly sensitive to changes occurring at 45 degrees north and south latitude. This discovery led to scientists finally being able to answer the long-standing question of why the axis drifts in the first place. The axis wobble to the East or West was caused by dry or wet years in Eurasia.

At what speed does the Earth move around the Sun?

In addition to the speed of the Earth's rotation on its axis, our planet also orbits the Sun at a speed of about 108,000 km per hour (or approximately 30 km per second), and completes its orbit around the Sun in 365,256 days.

It was only in the 16th century that people realized that the Sun is the center of our solar system, and that the Earth moves around it, rather than being the fixed center of the Universe.