Our planet is constantly in motion:
- rotation around its own axis, movement around the Sun;
- rotation together with the Sun around the center of our galaxy;
- motion relative to the center of the Local Group of galaxies and others.
Earth's motion around its own axis
Rotation of the Earth around its axis(Fig. 1). An imaginary line is taken for the earth's axis, around which it rotates. This axis is deviated by 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. If viewed from North Pole, then the rotation of the Earth occurs counterclockwise or, as is commonly believed, from west to east. The planet makes a complete rotation around its axis in one day.
Rice. 1. Rotation of the Earth around its axis
A day is a unit of time. Separate sidereal and solar days.
sidereal day is the amount of time it takes the earth to rotate on its axis with respect to the stars. They are equal to 23 hours 56 minutes 4 seconds.
solar day is the amount of time it takes for the earth to rotate on its axis with respect 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 surface of the Earth 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 464 m / s, and at a latitude of 65 ° - only 195 m / s.
The rotation of the Earth around its axis in 1851 was proved by J. Foucault in his experiment. In Paris, in the Pantheon, a pendulum was hung under the dome, and under it a circle with divisions. With each subsequent movement, the pendulum turned out to be on new divisions. This can only happen if the surface of the Earth under the pendulum rotates. The position of the swing 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.
As the earth rotates, there is centrifugal force who plays important role in shaping the shape of the planet and reduces the force of gravity.
Another important consequence axial rotation is the formation of a turning force - Coriolis forces. In the 19th 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 - 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 of 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 take predominantly western direction, and in tropical latitudes - east. A similar manifestation of the Coriolis force is found in the direction of motion ocean waters. The asymmetry of river valleys is also associated with this force (the right bank is usually high in the Northern Hemisphere, in the Southern - the left).
The rotation of the Earth around its axis also leads to the movement of solar illumination across 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 animate and inanimate nature. The circadian rhythm is closely related to light and temperature conditions. The daily course of temperature, day and night breezes, etc. are well known. Daily rhythms also occur in wildlife - photosynthesis is possible only during the day, most plants open their flowers in different watches; 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, a zone time account was adopted, that is, the entire surface of the Earth was divided into 24 time zones of 15 ° each. Behind standard time take the local time of the middle meridian of each zone. Neighboring time zones differ by one hour. The boundaries of the belts are drawn taking into account political, administrative and economic boundaries.
The zero belt is Greenwich (after the name of the Greenwich Observatory near London), which runs on both sides of prime meridian. The time of the zero, or initial, meridian is considered World Time.
Meridian 180° accepted as international date measurement line- a conditional line on the surface of the globe, on both sides of which the hours and minutes coincide, and calendar dates differ by one day.
For more rational use summer daylight in 1930 in our country was introduced maternity time, ahead of the zone by one hour. To do 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, between April and October, the time has been moved forward one hour. This so-called summer time. It is introduced to save energy. In summer, Moscow is two hours ahead of standard time.
The time zone in which Moscow is located is Moscow.
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 considered that there are 365 days in a year, and every four years, when 24 hours out of six hours “accumulate”, there are not 365, but 366 days in a year. This year is called leap year, 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 Greek. peri- near, around and helios- Sun) - the closest point of the orbit 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 in aphelion(from 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. 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 sunrise and sunset change, the duration of the bright 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 inclination of the Earth's axis to the plane of its movement around the Sun, an uneven distribution of solar radiation during a year. This is how the seasons change, which is typical for all planets that have an inclination of the axis of rotation to the plane of its orbit. (ecliptic) different from 90°. The orbital speed of a planet in the Northern Hemisphere is higher in winter time and less in summer. Therefore, the winter half-year lasts 179, and the summer half-year - 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 °, not only the change of seasons is observed on our planet, but also a change in the length of day and night.
The rotation of the Earth around the Sun and the change of seasons on Earth are shown in Fig. 81 (equinoxes and solstices according to the seasons in the Northern Hemisphere).
Only twice a year - on the days of the equinox, the length of day and night on the whole Earth is almost the same.
Equinox- the moment at which the center of the Sun, during its apparent annual movement along the ecliptic, crosses celestial equator. There are spring and autumn equinoxes.
The inclination of the Earth's axis of rotation around the Sun on the equinoxes of March 20-21 and September 22-23 is 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 vertically at the equator.
The longest day and shortest night occur on the summer solstice.
Rice. 5. Illumination of the Earth by the Sun on the days of the equinox
Solstice- the moment of passage by the center of the Sun of the points of the ecliptic, the most distant from the equator (solstice points). There are summer and winter solstices.
On the day of the summer solstice on June 21-22, the Earth takes 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, whose latitude is 23 ° 27 "All day and night, 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 ") turns out to be illuminated. Beyond it, on this day, the earth's surface is not illuminated.
In a day winter solstice On December 21-22, everything happens the other way around (Fig. 6). The sun's rays are already falling sheer on the southern tropic. Lighted 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 spring equinox.
Rice. 6. Illumination of the Earth on the day of the winter solstice
At two parallels of the Earth on the days of the solstice, the Sun at noon is directly above the head of the observer, that is, at the zenith. Such parallels are called tropics. On the Tropic of the North (23° N), the Sun is at its zenith on June 22, on the Tropic of the South (23° S) on December 22.
At the equator, day is always equal to night. The angle of incidence of the sun's rays on the earth's surface and the length of the day there change little, so the change of seasons is not expressed.
arctic circles 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 fall below the horizon. The farther 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 it lasts 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 this miraculous phenomenon nature, like white nights. White Nights- these are bright nights at the beginning of summer, when the evening dawn converges with the morning dawn and twilight lasts all night. They are observed in both hemispheres at latitudes exceeding 60°, when the center of the Sun at midnight falls 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 on Earth, there are five lighting belts. The hot belt lies between the Northern and Southern tropics (the Tropic of Cancer and the Tropic of Capricorn), occupies 40% of the earth's surface and differs the largest number heat coming from the sun. Between the tropics and the Arctic Circles in the Southern and Northern Hemispheres there are moderate zones of illumination. The seasons of the year are already expressed here: the farther from the tropics, the shorter and cooler the summer, the longer and colder winter. The polar belts in the Northern and Southern Hemispheres are limited by the Arctic Circles. Here, the height of the Sun above the horizon during the year is low, so the amount of solar heat is minimal. The polar zones are characterized by polar days and nights.
Depending on the annual movement of the Earth around the Sun are not only the change of seasons and the associated uneven illumination of the earth's surface across latitudes, but also a significant part of the processes in geographical envelope: seasonal change of weather, 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 celestial bodies. The calendar uses astronomical phenomena - the change of seasons, day and night, change lunar phases. The first calendar was Egyptian, created in the 4th century. BC e. From January 1, 45, Julius Caesar introduced Julian calendar, which is still used by Russian Orthodox Church. Due to the fact that the duration of the Julian year is longer than the astronomical one by 11 minutes 14 seconds, by the 16th century. an “error” of 10 days accumulated - the day of the vernal equinox did not come on March 21, but on March 11. This mistake was corrected in 1582 by a decree of Pope Gregory XIII. The count of days was moved forward by 10 days, and the day after October 4 was prescribed to be considered Friday, but not October 5, but October 15. The spring equinox was again returned to March 21, and the calendar became known as the Gregorian. It was introduced in Russia in 1918. However, it also has a number of drawbacks: unequal duration of months (28, 29, 30, 31 days), inequality of quarters (90, 91, 92 days), inconsistency of numbers of months by days of the week.
Movement around the axis of rotation is one of the most common types of movement of objects in nature. In this article, we will consider this type of movement from the point of view of dynamics and kinematics. We also present formulas relating the main physical quantities.
What movement are we talking about?
In the literal sense, we will talk about moving bodies around a circle, that is, about their rotation. A prime example such movement is the rotation of the wheel of a car or bicycle while moving vehicle. Rotation around its axis of a figure skater performing complex pirouettes on ice. Or the rotation of our planet around the Sun and around its own axis inclined to the plane of the ecliptic.
As you can see, an important element of the type of movement under consideration is the axis of rotation. Each point of an arbitrary-shaped body makes circular motions around it. The distance from the point to the axis is called the radius of rotation. Many properties of the whole system depend on its value. mechanical system, such as moment of inertia, linear speed and others.
If the reason for the linear translational movement of bodies in space is the force acting on them external force, then the cause of motion around the axis of rotation is the external moment of force. This quantity is described as the vector product of the applied force F¯ and the distance vector from the point of its application to the axis r¯, that is:
The action of the moment M¯ leads to the appearance angular accelerationα¯ in the system. Both quantities are related to each other through a certain coefficient I by the following equality:
The quantity I is called the moment of inertia. It depends both on the shape of the body and on the distribution of mass inside it and on the distance to the axis of rotation. For a material point, it is calculated by the formula:
If the external is zero, then the system retains its angular momentum L¯. This is another vector quantity, which, according to the definition, is equal to:
Here p¯ is the linear momentum.
The momentum conservation law L¯ is usually written in the following form:
Where ω is the angular velocity. It will be discussed further in the article.
Kinematics of rotation
Unlike dynamics, this branch of physics considers exclusively practical important quantities associated with a change in the position of bodies in space over time. That is, the objects of study of the kinematics of rotation are velocities, accelerations and angles of rotation.
First, let's introduce the angular velocity. It is understood as the angle through which the body makes a turn per unit of time. The formula for the instantaneous angular velocity is:
If the body rotates through the same intervals of time equal angles, then the rotation is called uniform. For him, the formula for the average angular velocity is valid:
ω is measured in radians per second, which in the SI system corresponds to reciprocal seconds (s -1).
In the case of non-uniform rotation, the concept of angular acceleration α is used. It determines the rate of change in time of the value ω, that is:
α \u003d dω / dt \u003d d 2 θ / dt 2
α is measured in radians per square second (in SI - s -2).
If the body initially rotated uniformly with a speed ω 0, and then began to increase its speed with constant accelerationα, then such a motion can be described the following formula:
θ = ω 0 *t + α*t 2 /2
This equality is obtained by integrating the angular velocity equations with respect to time. The formula for θ allows you to calculate the number of revolutions that the system will make around the axis of rotation in time t.
Linear and angular speeds
Both speeds are related to each other. When talking about the speed of rotation around an axis, they can mean both linear and angular characteristics.
Let's assume that some material point rotates around an axis at a distance r with a speed ω. Then its linear speed v will be equal to:
The difference between linear and angular speed is significant. Thus, ω does not depend on the distance to the axis during uniform rotation, while the value of v increases linearly with increasing r. The latter fact explains why, with an increase in the radius of rotation, it is more difficult to keep the body on a circular trajectory (its linear velocity and, as a result, inertial forces increase).
The task of calculating the speed of rotation around its axis of the Earth
Everyone knows that our planet in the solar system performs two types of rotational motion:
- around its axis;
- around the star.
Let us calculate the speeds ω and v for the first of them.
Angular speed not difficult to determine. To do this, remember that the planet makes a complete revolution equal to 2 * pi radians in 24 hours ( exact value 23 h 56 min. 4.1 sec.). Then the value of ω will be equal to:
ω \u003d 2 * pi / (24 * 3600) \u003d 7.27 * 10 -5 rad / s
The calculated value is small. Let's show now how much absolute valueω differs from that for v.
Let us calculate the linear velocity v for points lying on the surface of the planet at the latitude of the equator. Since the Earth is an oblate ball, the equatorial radius is slightly larger than the polar one. It is 6378 km. Using the formula for the connection of two velocities, we obtain:
v \u003d ω * r \u003d 7.27 * 10 -5 * 6378000 ≈ 464 m / s
The resulting speed is 1670 km/h, which is greater than the speed of sound in air (1235 km/h).
The rotation of the Earth around its axis leads to the appearance of the so-called Coriolis force, which should be taken into account when flying. ballistic missiles. It is also the cause of many atmospheric phenomena, such as the deviation of the direction of the trade winds to the west.
The earth is always in motion. Although it seems that we are standing motionless on the surface of the planet, it is constantly rotating around its axis and the Sun. This movement is not felt by us, as it resembles flying in an airplane. We are moving at the same speed as the plane, so we don't feel like we are moving at all.
At what speed does the earth rotate on its axis?
The earth rotates once on its axis every 24 hours. (to be precise, in 23 hours 56 minutes 4.09 seconds or 23.93 hours). Since the circumference of the Earth is 40075 km, any object at the equator rotates at a speed of approximately 1674 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 northern latitude) and (90 degrees south latitude), the speed is effectively zero because the pole points rotate at a very slow speed.
To determine speed at any other latitude, simply multiply the cosine of latitude by the planet's rotational 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 is easy to determine using a calculator or look 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/h;
- 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/h;
- 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 to within milliseconds. The Earth's rotation typically has five-year cycles of deceleration and acceleration, and Last year the slowdown cycle is often intertwined with the surge in earthquakes around the world.
As 2018 is the latest in a slowdown cycle, scientists expect growth this year seismic activity. Correlation is not causation, but geologists are always looking for tools to try and predict when the next big earthquake is going to happen.
Oscillation of the earth's axis
The earth wobbles slightly as it rotates as its axis drifts at the poles. It has been observed that the drift of the earth's axis has accelerated since 2000, moving at a rate of 17 cm per year to the east. Scientists have found 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.
Axis drift is expected to be particularly sensitive to changes occurring at 45 degrees north and south latitude. This discovery led to the fact that scientists were finally able to answer the long-standing question of why the axis drifts at all. The wobble to the East or West was caused by dry or wet years in Eurasia.
How fast is the earth moving around the sun?
In addition to the speed of the Earth's rotation on its axis, our planet also rotates around the Sun at a speed of about 108,000 km per hour (or about 30 km per second), and completes its orbit around the Sun in 365,256 days.
It wasn't until 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 stationary center of the universe.
We are all inhabitants of the most beautiful planet in the universe, it is called "blue" because of the abundance of water. It is the only one in the solar system, but all good things come to an end sooner or later. Have you ever wondered if the Earth stops, what will happen? We will try to find the answer to this question in this article.
Everyone knows from the time of the school bench that our earth has the shape of a ball and rotates around its axis. It is also in continuous motion around our source of heat and light, the Sun. But what is the reason for the rotation of the Earth?
All these questions are quite interesting, for sure, every inhabitant of our planet has asked this at least once in his life. School course gives us little information of this kind. For example, everyone knows that as a result of the movement of the Earth, we have a change of day and night, the air temperature that is familiar to all of us is maintained. But this is not enough, because this process is not only limited to this.
Rotation around the Sun
So, we figured out that our planet is always in motion, but why and at what speed does the Earth rotate? It is important to know that all the planets in the solar system rotate at a certain speed, and all in the same direction. Coincidence? Of course not!
Long before the appearance of man, our planet was formed, it arose in a hydrogen cloud. After that, a strong push was obtained, as a result of which the cloud began to rotate. In order to answer the question “why”, let us recall that each particle, when passing through a vacuum, has its own inertia, while all particles balance it.
Thus, the entire solar system rotates faster and faster. Our Sun was formed from this, and then all the other planets, and they inherited those very movements from the luminary.
Rotations around own axis
This question is of interest to scientists even now, there are many hypotheses, but we will give the most plausible one.
So, we have already said in the previous paragraph that the entire solar system was formed from the accumulation of "garbage", which was accumulated as a result of the fact that the young, at that time, Sun attracted it. Despite the fact that most of its mass went to our Sun, planets nevertheless formed around. Initially, they did not have a form familiar to us.
Sometimes, colliding with objects, they collapsed, but they had the ability to attract smaller particles, and so they gained their mass. Our planet was forced to rotate by several factors:
- Time.
- Wind.
- Asymmetry.
And the last is not a mistake, then the Earth resembled the shape of a snowball made by a small child. wrong shape made the planet unstable, it was exposed to wind and solar radiation. Despite, she got out of an unbalanced position and began to spin, pushed by the same factors. In short, our planet does not move by itself, but it was pushed many billions of years ago. We have not specified how fast the Earth rotates. She is always on the move. And in almost twenty-four hours it makes a complete revolution around its axis. This movement is called diurnal. The speed of rotation is not the same everywhere. So at the equator, it is approximately 1670 kilometers per hour, and the North and South Poles may even remain in place.
But besides this, our planet is still moving along a different trajectory. A complete revolution of the Earth around the Sun takes three hundred and sixty-five days and five hours. This explains what exists leap year, that is, it contains one more day.
Is it possible to stop?
If the Earth stops, what will happen? Let's start with the fact that the stop can be considered both around its axis and around the Sun. We will analyze all the options in more detail. In this chapter, we will discuss some general points, and is it possible at all.
If we consider a sharp stop in the rotation of the Earth around its axis, then this is practically unrealistic. This can only be caused by a collision with a large object. We’ll clarify right away that there will no longer be any difference whether the planet rotates or even flew away from its orbit, since a stop can be caused by such large object that the Earth simply could not withstand such a blow.
If the Earth stops, what will happen? If a sudden stop is practically impossible, then slow braking is quite possible. Although it is not felt, our planet is already gradually slowing down.
If we talk about flying around the Sun, then stopping the planet in this case is something from the realm of fantasy. But we will discard all probabilities and assume that this did happen. We suggest that you analyze each case separately.
abrupt stop
Although this option is hypothetically impossible, we still assume. If the Earth stops, what will happen? The speed of our planet is so great that a sudden stop for any reason will simply demolish everything on it.
First, in what direction does the earth rotate? From West to East at a speed of more than five hundred meters per second. From this we can assume that everything that moves on the planet will continue to move at a speed of more than 1.5 thousand kilometers per hour. The wind that will blow at the same speed will cause the strongest tsunami. On one hemisphere there will be six months a day, and then, those who will not be burned highest temperature, will finish six months hard frost and nights. What if they are still alive after that? The radiation will kill them. In addition, after the Earth stops, our core will make a few more revolutions, while volcanoes will erupt in places where they have not met before.
The atmosphere also will not stop its movement instantly, that is, there will be a wind blowing at a speed of 500 meters per second. In addition, partial loss of the atmosphere is possible.
This version of the catastrophe is the best outcome for humanity, because everything will happen so quickly that not a single person will simply have time to come to his senses, will not understand what is happening. Since the most likely outcome is an explosion of the planet. Another thing is the slow and gradual stop of the planet.
For many, the first thing that comes to mind is eternal day on one side, and eternal night on the other, but this, in fact, is not strong a big problem, compared to the rest.
soft stop
Our planet is slowing down its rotation, scientists say that a person will not find it completely stopped, since it will happen in billions of years, and long before that the Sun will increase in volume and simply burn the Earth. But, nevertheless, we will simulate a stop situation in the foreseeable future. Just to begin with, let's deal with the question: why does the slow stop occur?
Previously, a day on our planet lasted about six hours, and this factor strong impact provided by the moon. But how? It causes the water to vibrate with its force of attraction, and as a result of this process, a slow stop occurs.
It happened anyway
We are waiting for eternal night or eternal day in one of the hemispheres, but this is not the biggest problem compared to the redistribution of land and ocean, which will lead to mass destruction all living things.
Where there is sun, all plants will gradually die out, and the soil will crack from drought, but the other side is the snowy tundra. The most suitable area for habitation will be in between, where there will be an eternal sunrise or sunset. At the same time, these territories will be quite small. Land will be located only at the equator. The North and South Poles will be two large oceans.
It is no exception that a person will need to adapt to exist in the ground, and spacesuits will be needed for walking on the surface.
No movement around the sun
This scenario is simple, everything that was on the front side will fly away into the free space of space, because our planet is moving at a very high speed, while others will receive an equally strong impact on the ground.
Even if the Earth gradually slows down its movement, then in the end it will fall into the Sun, and this whole process will take sixty-five days, but no one will live to the last, since the temperature will be about three thousand degrees Celsius. According to the calculations of scientists, in a month on our planet the temperature will reach 50 degrees.
This scenario is practically unrealistic, but the absorption of the Earth by the Sun is a fact that cannot be avoided, but humanity will not be able to catch this day.
Earth is out of orbit
This is the most fantastic option. No, we will not go on a journey through space, because there are laws of physics. If at least one planet from the solar system flies out of orbit, then it will bring chaos to the movement of all the others, as a result, it will fall into the "paws" of the Sun, which will absorb it, attracting it with its mass.
Like other planets of the solar system, it makes 2 main movements: around its own axis and around the sun. Since ancient times, it is on these two regular movements that the calculation of time and the ability to draw up calendars have been based.
A day is the time of rotation around its own axis. A year is a revolution around the sun. The division into months is also in direct connection with astronomical phenomena - their duration is associated with the phases of the moon.
Rotation of the Earth around its own axis
Our planet rotates around its own axis from west to east, that is, counterclockwise (when viewed from the North Pole.) The axis is a virtual straight line that intersects Earth in the North and south poles, i.e. the poles have a fixed position and do not participate in rotary motion, while all other locations on the earth's surface rotate, and the rotation speed is not identical and depends on their position in relation to the equator - the closer to the equator, the higher the rotation speed.
For example, in the region of Italy, the rotation speed is approximately 1200 km / h. The consequences of the rotation of the Earth around its axis are the change of day and night and the apparent movement of the celestial sphere.
Indeed, one gets the impression that the stars and others celestial bodies of the night sky move 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 evidence that the Earth rotates on 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, immovable position in space.
Foucault pendulum
Irrefutable proof that the Earth rotates around its own axis was presented in 1851 by Foucault, who conducted the famous experiment with a pendulum.
Imagine that, being at the North Pole, we set a pendulum in oscillatory motion. The external force acting on the pendulum is gravity, while it does not affect the change in the direction of oscillation. If we prepare a virtual pendulum that leaves tracks on the surface, we can make sure that after a while the tracks move in a clockwise direction.
This rotation can be associated with two factors: either with the rotation of the plane on which the pendulum oscillates, or with the rotation of the entire surface.
The first hypothesis can be rejected, taking into account that there are no forces on the pendulum capable of changing the plane of oscillatory motions. It follows from this that it is the Earth that rotates, and it makes movements around its own axis. This experiment was carried out in Paris by Foucault, he used a huge pendulum in the form of a bronze sphere weighing about 30 kg, suspended from a 67-meter cable. The starting point of oscillatory movements was fixed on the surface of the floor of the Pantheon.
So, it is the Earth that rotates, and not the celestial sphere. People observing the sky from our planet fix the movement of both the Sun and the planets, i.e. All objects in the universe are in motion.
Time criterion - day
A day is the length of time it takes for the Earth to complete one rotation around its own axis. There are two definitions of the term “day”. A "solar day" is the time interval of the Earth's rotation, in which . Another concept - "sidereal day" - implies a different starting point - any star. The duration of the two types of day is not identical. The longitude of a sidereal day is 23 h 56 min 4 s, while the longitude of the solar day is 24 hours.
The different duration is due to the fact that the Earth, rotating around its own axis, performs and orbital rotation around the sun.
In principle, the duration of a solar day (although it is taken as 24 hours) is a variable value. This is due to the fact that the movement of the Earth in its orbit occurs at a variable speed. When the Earth is closer to the Sun, the speed of its movement in orbit is higher, as it moves away from the sun, the speed decreases. In this regard, such a concept as “average solar day” was introduced, namely, their duration is 24 hours.
Circulation around the Sun at a speed of 107,000 km / h
The speed of the Earth around the Sun is the second main movement of our planet. The earth moves in an elliptical orbit, i.e. the orbit is elliptical. When it 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 150 million kilometers. Astronomy uses a unit to measure distances within the solar system; it is called the “astronomical unit” (AU).
The speed at which the Earth moves in its 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 ', this is a constant value.
If you watch the Sun from the Earth, it seems that it is it that moves across the sky during the year, passing through the stars and that make up the Zodiac. In fact, the Sun also passes through the constellation Ophiuchus, but it does not belong to the Zodiac circle.
