Hello dear readers! Today I would like to touch on the topic of the Earth and, and I thought that a post on how the Earth rotates will be useful to you 🙂 After all, day and night, and also the seasons, depend on it. Let's get to know everyone better.

Our planet rotates on its axis and around the sun. When it makes one revolution around its axis, one day passes, and when it circles the Sun, one year. More on this below:

Earth axis.

earth axis(axis of rotation of the Earth) – is the line around which diurnal rotation Earth; this line passes through the center and intersects the surface of the Earth.

The tilt of the Earth's axis of rotation.

The axis of rotation of the Earth is inclined to the plane at an angle of 66°33´; thanks to this happens . When the Sun is over the Tropic of the North (23°27´N), summer begins in the Northern Hemisphere, and the Earth is at its furthest distance from the Sun.

When the Sun rises over the Tropic of the South (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 the earth's axis, but leads to the fact that it moves along a circular cone. This movement is called precession.

The North Pole is pointing towards the North Star. The earth's axis over the next 12,000 years, as a result of precession, will pass approximately halfway, and will be directed to the star Vega.

About 25,800 years constitutes a complete cycle of precession and significantly influences the climate cycle.

Twice a year, when the Sun is directly over the equator, and twice a month, when the Moon is similar position, the attraction due to precession decreases to zero and there is a periodic increase and decrease in the rate of precession.

Such oscillatory movements Earth's axes are known as nutation, which peaks every 18.6 years. In terms of its impact on climate, this periodicity ranks second after change of seasons.

Rotation of the Earth around its axis.

Earth's daily rotation the movement of the earth is counterclockwise, or from west to east when viewed from North Pole peace. The rotation of the Earth determines the length of the day and causes day and night to change.

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, which is one year or 365 ¼ days.

Every four years, another day is added to the calendar, because for each such turn, except for 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 prolongs the day by about 1/1000 of every century.

Judging by the geological data, the rate of rotation of the Earth could change, but not more than 5%.

The earth revolves around the sun 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 the most long distance 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 advance and retreat of glaciers during ice ages are associated with its individual stages.

Everything in our vast universe very complex and precise. And our Earth is just a point in it, but it is our native home, which we learned a little more about from a post about how the Earth rotates. See you in new posts about the study of the Earth and the Universe🙂

For an observer located 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 hides behind the horizon line. 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. At the same time, 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 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, on March 21 and September 23, the Sun equally illuminates the Northern and Southern hemispheres. These moments are known as the autumnal equinox. In March, autumn begins in the Northern Hemisphere, in the Southern Hemisphere. In September, on the other hand, North hemisphere autumn comes, and in the South - spring.

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 22 - the day has the shortest duration, and the night is the longest. In the Southern Hemisphere, the opposite is true.

polar night

Due to the tilt of the earth's axis, the polar and subpolar regions of the Northern Hemisphere in winter months find themselves without sunlight - the sun does not rise above the horizon at all. This phenomenon is known as polar night. A similar polar night exists for the subpolar regions of the Southern Hemisphere, the difference between them is exactly half a year.

What gives the Earth its rotation around the Sun

The planets cannot but revolve around their luminaries - otherwise they would simply be attracted and burned out. The uniqueness of the Earth lies in the fact that the tilt of its axis of 23.44 degrees 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 ensure the diversity of the earth's flora and fauna. Heating change earth's surface provides the movement of air masses, and hence the precipitation in the form of rain and snow.

The distance from the Earth to the Sun of 149,600,000 km also turned out to be optimal. A little further, and the water on Earth would be only in the form of ice. Any 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 multitude of factors.

“And yet she turns!” - this famous phrase of the great Italian astronomer G. Galileo most likely belongs to the realm of legends (it is unlikely that the Holy Inquisition would have allowed him such a formal renunciation), but it has forever remained in the memory of mankind as a kind of monument of how much work it took to understand that ours rotates , and not only around the Sun, but also around its axis. But proving the rotation of the Earth was only the beginning, it was still necessary to explain why this happens!

To find an explanation for this, we will have to travel back to those distant times when the solar system in general and the Earth in particular were born from a huge gas and dust cloud. This cloud itself also rotated - without this, nothing would have happened, and it would have floated in space, remaining only a cloud and nothing more. But the rotation made it shrink, and the particles that make it up collided with each other and "clumped together." At first these were small particles, then large ones were formed from them, continuing to collide with each other, then the same thing happened with fairly large bodies - planetesimals ... but no matter how large the colliding bodies were, the impulses of their movement did not disappear! The new formation continued to rotate by inertia, having received an additional impulse from the collision of bodies merged with each other.

Collision with large objects could also affect the rotation of already "ready" (or almost "ready") planets. For example, Venus rotates differently than all other planets - in the opposite direction, and Uranus generally rotates, "lying on its side", i.e. its axis of rotation differs only slightly from the plane of the orbit. Scientists suggest that this is due to the collision with large objects that took place during the "youth" solar system, when there were an order of magnitude more planets, and many of them moved in emergency orbits (i.e., in such orbits that made collisions inevitable). In this regard, we were “lucky”: the Earth also survived a collision with a very major planet, about the size of Mars (astronomers even gave it a name - Theia), but this did not affect its rotation, in any case, it did not affect it in the same way as it happened with Venus or Uranus.

However, it would be wrong to say that the collision with Theia did not affect the rotation of the Earth at all. As a memento of this great clash, we received our only natural satellite- The moon, and now it really affects the rotation of the Earth! The point is that one heavenly body its gravity is quite capable of slowing down the rotation of another, so the moon slows down the rotation of the earth. True, we are talking about fractions of a second per year - but after all, over centuries and millennia, fractions of seconds add up to seconds, seconds to minutes, and minutes to hours! The English astronomer R. Stephenson analyzed astronomical observations sages of Babylon, Egypt and other civilizations ancient world starting from 700 BC It turned out that if we were transported by a time machine to 700 BC. at the same time of day, we would have to set the clock back to 7 o'clock! An impressive deviation ... and in the days when dinosaurs lived, the day was 21 hours. Why, if there were no Moon, the Earth day would last only six hours!

However, the speed of rotation of the planets is affected not only by the gravity of other bodies, but also by the density of its matter. The closer the planet is to the Sun, the higher its density, which is why the small Mercury rotates around its axis much more slowly than the giant Jupiter.

We know perfectly well that our planet rotates around its axis, thanks to which we see day and night. However, the Earth, although very slowly, is gradually slowing down. Scientists say that it will stop completely in many billions of years. People will probably not catch this moment, because by that time the Sun will increase in size and destroy first life on Earth, and then the planet itself. In this article, we will try to simulate the following situation: what will happen if the earth stops rotating in the foreseeable future.

Why does rotation happen at all?

According to the generally accepted theory, the rotation of the Earth is due to processes that took place even at the time of its formation. In those days the clouds space dust huddled together in one "heap", to which other cosmic bodies were attracted. As a result of this confusion, the planet formed over billions of years. And its rotation is due to the inertia that remained after the collision with those very cosmic bodies.

Why is the Earth slowing down?

At the dawn of its existence, our planet rotated much faster. The day then was about 6 hours. The opinion became popular, then most of all the change in the speed of the earth's rotation is influenced by the moon. With its force of attraction, it causes fluctuations in the water level in the earth's oceans. Because of the tides, the Earth seems to sway, which leads to its very slow deceleration.

What would happen if the Earth suddenly stopped?

Yes, this option is almost unbelievable, but why not?

Today, the speed of rotation of the Earth is no less than 1670 km / h. With the sudden stop of the planet, everything that was on its surface, including people, will be instantly swept away due to the effect of centrifugal force. In fact, the Earth will stop, and objects on its surface will continue to move.

This option is perhaps more acceptable to people, because everything will happen so quickly that no one will understand anything. But in the case of the gradual deceleration of the Earth, we will have to experience many devastating consequences.

What will happen if the Earth gradually stops its rotation?

Now let's move on to a more realistic simulation of the situation, if our planet began to slow down much faster and humanity still caught the moment of its stop.

We already know that our planet will stop only in billions of years, but hypothetically it could happen even earlier. Scientists do not exclude that the planet's rotation speed may decrease, for example, due to a collision with an asteroid. Such an event in itself would be disastrous for earthlings, and a slowdown in the planet's rotation would be an unpleasant bonus to everything. But let's imagine that this happened without the participation of huge asteroids, but for more "invisible reasons."

Light and darkness

The first thing that comes to mind is eternal day on one hemisphere and eternal night on the other. It's actually small compared to others. global changes starting from terrible cataclysms and ending with the redistribution of the waters of the World Ocean, which will lead to the mass death of all life on the planet.

The concept of day will disappear. On one side of the Earth there will be eternal day. At the same time, constant sunshine will destroy many plants, and the soil will dry out and crack. Dark side The earth will be like a snowy tundra. Scientists believe that an intermediate region between day and night will be more or less suitable.

Equator without oceans

The waters of the oceans will change their location, shifting from the equator to the poles. I.e the equatorial line will become one large piece of land, and many continental zones closer to the poles will be flooded. The fact is that our planet is slightly convex due to rotation, so it has a kind of “hump” along the equator. Thus, after the Earth stops, the waters of the World Ocean will cease to be evenly retained and will actually “drain” from the equator.

Climate and the habitability of the planet

In addition to the fact that land and oceans will look different on Earth, the climate will also change dramatically. Right now the winds are blowing parallel to the equator, but if what happens happens, they will blow from the equator towards the poles. The trends will naturally change. What kind climatic conditions will be in a particular region is difficult to say, but you can be sure that one hemisphere will be arid, and the other - incredibly cold.

The atmosphere of the Earth, like ocean waters, will become denser closer to the poles, and thinner at the equator.

Due to the fact that the metal core of the Earth rotates, there is a magnetic field around it. It provides protection from the destructive solar wind and from high-energy particles from space. There will be no rotation magnetic field, and therefore, all living things will die under direct sunlight.

Among the representatives of animal and plant species will be inevitable. Flooding of large areas, climate change, natural disasters- all this will clearly reduce the diversity of life on Earth.

Can people survive?

Certainly people would be able to adapt to the new conditions. There aren't many places left to survive. People will be able to live in small areas on the border of day and night. In such places there will be an eternal dawn or sunset, depending on the hemispheres. In addition, it will not be possible to settle along the entire “favorable line”, since a large part of the land will be flooded by the oceans, and you will have to choose the area where there will be an optimal Atmosphere pressure and temperature.

It is possible that due to dangerous cosmic radiation, people will have to move underground and organize their life there, and spacesuits will be needed to walk on the surface.

Our planet is in constant motion, it revolves 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 with respect to the plane of the Earth. People cannot notice the moment of rotation, because all objects are moving 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 rotation around the axis is completed within one sidereal day, consisting of 23 hours 56 minutes and 4 seconds. During this interval, then one or the other side of the planet turns towards the Sun, receiving from it a different amount of heat and light. In addition, the rotation of the Earth around its axis affects its shape (flattened poles are the result of the planet's rotation around the axis) and the deviation when bodies move in a horizontal plane (rivers, currents and winds of the Southern Hemisphere deviate to the left, Northern - to the right).

Linear and angular speed of rotation

(Earth rotation)

The linear speed of the Earth's rotation around its axis is 465 m / s or 1674 km / h in the equator zone, as we 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 - 260 m / s (almost half as much).

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

Why does day turn into night

(The change of night and day)

The time of a complete rotation 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 at the mercy 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 a high temperature (up to 100 degrees Celsius) and all the water would evaporate, on the other side, frost would rage and the water would be 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 tilted with respect to the earth's surface at a certain angle, its sections receive different amounts of heat and light at different times, which causes the change of seasons. According to the astronomical parameters necessary to determine the time of year, some 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 is turned towards the Sun for a shorter amount of time and, accordingly, receives less heat and light, hello winter-winter, 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 already receives more heat and light, the days become longer, the Sun rises higher - summer is coming.

If the Earth were located in relation to the Sun exclusively in a 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.