Very many features we are used to since childhoodlives are the result of cosmic-scale processes. The alternation of day and night, seasons, the duration of the period during which the sun is above the horizon is related to how and with what speed the Earth rotates, with the peculiarities of its movement in space.
Imaginary line
Ось любой планеты — конструкция умозрительная, created for the convenience of describing the movement. If you mentally draw a line through the poles, this will be the axis of the Earth. Rotation around it is one of the two main movements of the planet.
The axis does not make up with the ecliptic plane(the plane of rotation of the Earth around the Sun) is 90º and deviates from the perpendicular by 23º27 ". It is believed that the planet rotates from west to east, that is, counterclockwise. Its movement around the axis looks like this if viewed at the North Pole.
Irrefutable evidence
Once it was believed that our planet is motionless,and the stars, fixed on the sky, revolve around it. For quite a long time in history no one was interested in the speed with which the Earth moves in orbit or around an axis, since the very concepts “axis” and “orbit” did not fit into the scientific knowledge of that period. Experimental evidence of the constant movement of the Earth around its axis was obtained in 1851 by Jean Foucault. It finally convinced everyone who in the nineteenth century still doubted it.
The experiment was conducted in the Paris Pantheon, underthe dome of which was placed a pendulum and a circle with divisions. Swaying, the pendulum shifted by several divisions with each new movement. This is possible only if the planet rotates.
Speed
How fast does the earth rotate around its axis?It is rather difficult to give an unequivocal answer to this question, since the speed of different geographical points is not the same. The closer the terrain to the equator, the higher it is. In the region of Italy, the speed, for example, is estimated at 1,200 km / h. On average, the planet overcomes 15º per hour.
With the speed of rotation of the Earth is connectedthe duration of the day. The length of time for which our planet makes one revolution around its axis is determined in two ways. To determine the so-called star or sidereal days, any star except the Sun is chosen as a reference system. They last 23 hours 56 minutes and 4 seconds. If our star is taken as the starting point, then the day is called solar. Their value is on average 24 hours. It varies somewhat depending on the position of the planet relative to the star, which affects both the speed of rotation around the axis and the speed with which the Earth orbits.
Around the center
The second most important movement of the planet is its"Circling" in orbit. The constant movement along a slightly elongated trajectory is felt by people most often as the seasons change. The speed with which the Earth moves around the Sun is expressed for us primarily in terms of time: one revolution takes 365 days 5 hours 48 minutes 46 seconds, that is, an astronomical year. The exact figure clearly explains why there is an extra day every four years in February. It represents the sum of hours accumulated during this time, not included in the adopted 365 days of the year.
Trajectory Features
As already noted, the speed with which the Earthis orbiting, due to the characteristics of the latter. The trajectory of the planet is different from the ideal circle, it is slightly elongated. As a result, the Earth is now approaching the luminary, now moving away from it. When the planet and the sun share the minimum distance, this position is called perihelion. The maximum removal corresponds to aphelion. The first falls on January 3, the second - on July 5. And for each of these points the question: “With what speed does the Earth rotate in orbit?” - has its own answer. For aphelium it is 29.27 km / s, for perihelion it is 30.27 km / s.
Day length
The speed with which the earth rotates in orbit,and on the whole, the movement of the planet around the Sun has a number of consequences that determine many nuances of our life. For example, these movements affect the length of the day. The sun is constantly changing its position in the sky: the points of sunrise and sunset are shifting, and a slightly different height of the star above the horizon at noon becomes. As a result, the length of the day and night changes.
These two quantities coincide only in the equinox,when the center of the sun crosses the celestial equator. The inclination of the axis in this case turns out to be neutral with respect to the luminary, and its rays fall vertically on the equator. The spring equinox falls on March 20-21, the autumn equilibrium falls on September 22-23.
Solstice
Once a year, the day reaches its maximum.in duration, and after six months - the minimum. These dates are called the solstice. Summer falls on June 21-22, and winter falls on December 21-22. In the first case, our planet is so located in relation to the sun, that the northern edge of the axis looks in the direction of the Sun. As a result, the rays fall vertically on the northern tropic and illuminate the entire region beyond the Arctic Circle. In the Southern hemisphere, on the contrary, the sun's rays reach only the area between the equator and the Arctic Circle.
During the winter solstice, events proceed in the same way, only the hemispheres change roles: the South Pole is illuminated.
Seasons
Position in orbit affects not only the fact thatwhat speed the earth moves around the sun. As a result of a change in the distance separating from the star, as well as the inclination of the axis of the planet throughout the year, solar radiation is unevenly distributed. And this, in turn, becomes the reason for the change of seasons. Moreover, the duration of the winter and summer semesters is different: the first is 179 days, and the second is 186. The same inclination of the axis relative to the ecliptic plane leads to this discrepancy.
Light Belts
Circling the Earth in orbit has one more consequence. Annual movement leads to a change in the position of the sun above the horizon, resulting in the planet formed light belts:
Hot are located on 40% of the Earth, between the southern and northern tropics. As the name implies, here comes the most heat.
Temperate belts - between the Arctic Circle and the Tropics - are characterized by a pronounced change of seasons.
The polar belts, located behind the Arctic Circles, are characterized by low temperatures throughout the year.
The motion of the planets in general and, in particular, the factwhat speed the Earth turns in orbit, affect other processes. Among them, the flow of rivers, seasons change, certain rhythms of life of plants, animals and humans. In addition, the rotation of the Earth due to its influence on the illumination and temperature of the surface affects agricultural work.
Today, what is the speed of the Earth’s rotation, what isits distance to the Sun, and other features associated with the motion of the planet, are studied in school. However, if you think about it, they are completely unobvious. When such a thought comes to mind, I would like to sincerely thank those scientists and researchers who, largely because of their extraordinary mind, were able to discover the patterns of Earth’s cosmic life, describe them, and then prove and explain to the rest of the world.
