Even in ancient times, watching the starry sky, people have noticed that the afternoon sun and the night sky - almost all the stars - at times repeat his way.This suggests that this phenomenon for two reasons.Or there is a rotation of the Earth around the Sun on the background of the still starry sky or heaven revolves around the Earth.Claudius Ptolemy, an eminent Greek astronomer, scientist and geographer, as decided this issue by convincing everyone that revolve around the sun and sky stationary Earth.Despite the fact that the geocentric system could not explain many astronomical phenomena, to live with it.
heliocentric system based on another version, won its recognition in the long and dramatic struggle.He died at the stake of Giordano Bruno, Galileo found an old "rightness" of the Inquisition, but "... yet it does move!»
Today, the Earth's rotation around the Sun is considered to be fully proven.In particular, the movement of our planet's orbit near the sun proved aberration of starlight and the parallax shift at a frequency equal to one year.Today, found that the direction of rotation of the Earth, or more precisely, its barycenter, the orbit coincides with the direction of its rotation axis, that is going from west to east.
There are many facts which show that the Earth moves in space in a very complex orbit.The Earth's rotation around the Sun is accompanied by her movement around the axis precession, nutation oscillations and rapid flight with the Sun within a spiral galaxy, which is also not standing still.
Earth's rotation around the sun, like the other planets, held in an elliptical orbit.Therefore, once a year, January 3, the Earth is as close to the Sun and once on July 5, is removed from it by the greatest distance.The difference between perihelion (147 million km.) And aphelion (152 million km.), Compared with the distance from the Sun to Earth is very small.
Moving along the orbit near the sun, our planet is doing 30 kilometers per second, and the revolution of the earth around the sun is completed within 365 d. 6 h. This - the so-called sidereal or sidereal year.For practical convenience is considered to be 365 days a year."Plus," 6:00 4 years add up to 24 hours, there is still one day.These, then (came running, extra) day and added to February every four years.Therefore, in our calendar include 3 years of 365 days and a leap year - the fourth year contains 366 days.
own axis of rotation of the Earth is inclined to the orbital plane at 66,5 °.In this regard, during the fall, the sun's rays at each point of the earth's surface at different angles.Thus, at different times at different points, the hemispheres obtained in one and the same time, different amounts of light and heat.Because of that, in temperate latitudes, seasons are sharply pronounced.At the same time during the year, the sun's rays fall on the equator on the ground at the same angle, so there seasons differ slightly from each other.
the summer solstice axis of the Earth is facing its northern end to the sun and its rays fall vertically at latitude 23,5 °.Therefore, from the equator to 66,5 °, day becomes longer overnight.To the north of the latitude 66,5 ° is the polar day.