Rotation of the Earth around the Sun and its meaning

Back in ancient times, observing the starry sky, people noticed that in the daytime the sun, and in the night sky - almost all the stars - from time to time repeat their path. This suggested that there are two reasons for this phenomenon. Or there is a rotation of the Earth around the Sun against the background of a fixed starry sky, or the sky revolves around the Earth. Claudius Ptolemy, an outstanding ancient Greek astronomer, scientist and geographer, seemed to have solved this question by convincing everyone that the Sun and the sky revolve around a stationary Earth. Despite the fact that the geocentric system could not explain many astronomical phenomena, they accepted it.

The heliocentric system, based on another version, won its recognition in a long and dramatic struggle. Killed at the stake Giordano Bruno, the elderly Galileo recognized the "rightness" of the Inquisition, but "... yet it spins!"

Today, the rotation of the Earth around the Sun is considered fully proven. In particular, the movement of our planet along the circumsolar orbit is proved by the aberration of stellar light and parallactic displacement with a periodicity equal to one year. Today it is established that the direction of rotation of the Earth, more precisely, its barycenter, coincides in orbit with the direction of its rotation about the axis, that is, it occurs from west to east.

There are many facts that say 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, nutational oscillations and rapid flight along with the Sun along a spiral within the Galaxy, which also does not stand still.

Rotation of the Earth around the Sun, like other planets, passes in an elliptical orbit. Therefore, once a year, on January 3, the Earth is as close to the Sun as possible, and once, on July 5, it leaves from it for the longest distance. The difference between perihelion (147 million km) and aphelion (152 million km), in comparison with the distance from the Sun to the Earth, is very small.

Moving along the circumsolar orbit, our planet does 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 considered to be 365 days a year. "Additional" 6 hours for 4 years in total give 24 hours, that is, one more day. These are some (run up, extra) days and add to February 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 located at an inclination to the orbital plane at 66.5 °. In this regard, during the year the sun's rays fall on every point of the earth's surface under the in Angles. 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 on the equator are falling to the ground at the same angle, and therefore the seasons there are slightly different from each other.

On the day of the summer solstice, the Earth's axis is facing its northern end toward the Sun, and its rays plummet to a latitude of 23.5 °. Therefore, starting from the equator to 66.5 °, the day becomes longer than the night. North of latitude 66.5 ° is a polar day.