Even in ancient times, observing the starry sky, people noticed that during the day the sun, and in the night sky - almost all the stars - repeat their path from time to time. This suggested that there were two reasons for this phenomenon. Either the Earth rotates around the Sun against the background of a fixed starry sky, or the sky rotates around the Earth. Claudius Ptolemy, an outstanding ancient Greek astronomer, scientist and geographer, seemed to have solved this issue by convincing everyone that the Sun and the sky revolve around the motionless Earth. Despite the fact that the geocentric system could not explain many astronomical phenomena, they put up with it.
The heliocentric system, based on another version, won its recognition in a long and dramatic struggle. Giordano Bruno died at the stake, the aged Galileo recognized the "correctness" of the Inquisition, but "… after all, it rotates!"
Today, the rotation of the Earth around the Sun is considered to be completely proven. In particular, the movement of our planet in a circumsolar orbitis proved by the aberration of starlight and parallactic displacement with a periodicity equal to one year. Today it has been established that the direction of rotation of the Earth, more precisely, its barycenter, coincides in orbit with the direction of its rotation around its axis, that is, it occurs from west to east.
There are many facts that indicate that the Earth moves in space in a very complex orbit. The rotation of the Earth around the Sun is accompanied by its movement around the axis, precession, nutation oscillations and rapid flight along with the Sun in a spiral within the Galaxy, which also does not stand still.
The rotation of the Earth around the Sun, like other planets, passes along elliptical orbit. Therefore, once a year, on January 3, the Earth is as close as possible to the Sun and once, on July 5, it moves away from it at the greatest distance. The difference between perihelion (147 million km) and aphelion (152 million km), compared to the distance from the Sun to the Earth, is very small.
Moving along the circumsolar orbit, our planet makes 30 km per second, and the Earth's revolution around the Sun is completed within 365 days 6 hours. This is the so-called sidereal, or stellar, year. For practical convenience, it is customary to consider 365 days a year. The "additional" 6 hours in 4 years add up to 24 hours, that is, one more day. These (running, extra) days are added to February once every 4 years. Therefore, in our calendar, 3 years include 365 days, and a leap year - the fourth year, contains 366 days.
The axis of the Earth's own rotation is inclined to the orbitalplane at 66.5°. In this regard, during the year, the sun's rays fall on every point on the earth's surface under in
th corners. Thus, at different times of the year, points on different hemispheres of the Earth receive at the same time an unequal amount of light and heat. Because of this, in temperate latitudes, the seasons have a pronounced character. At the same time, throughout the year, the sun's rays at the equator fall on the earth at the same angle, so the seasons there differ slightly from each other. it plummets to a latitude of 23.5°. Therefore, starting from the equator to 66.5°, the day becomes longer than the night. To the north of latitude 66.5° is the polar day.
