The earth's axis of our planet in the northern vector is directed to the point where there is a second-magnitude star, called Polyarnaya, in the tail part of the constellation of the Ursa Minor.
This star within a day delineates on the celestial sphere a small circle with a radius of about 50 minutes of arc.
Very long time, in the II century BC. E., the astronomer Hipparchus discovered that this point is mobile in the stellar sky and slowly moves towards the movement of the Sun.
Let us return to the question of the pole. Determination of its exact position among the stars is one of the most important tasks of astrometry, which deals with measurements of arcs and angles on the celestial sphere in order to determine the coordinates of stars and planets, proper motions and distances to stars, as well as solving practical astronomy problems important for geography, geodesy and navigation.
You can find the position of the world's pole by usingPhoto. Imagine a long-focus photographic camera, realized in the form of an astrograph, directed motionlessly onto the sky region near the pole. In such a photograph, each star will describe a more or less long arc of a circle with a single common center, which will be the pole of the world, the point where the rotation of the earth's axis is directed.
The plane of the celestial equator, beingperpendicular to the earth's axis, also changes its position, which causes the movement of the points of intersection of the equator with the ecliptic. In turn, the attraction of the Moon to the equatorial displacement of the Earth's masses tends to turn the Earth in such a way that its equatorial plane crosses the Moon. But in this case these forces act not on the water shell of the Earth, but on the masses forming the equatorial swelling of its ellipsoidal figure.
Imagine a ball inscribed in an earth ellipsoid,which he touches at the poles. Such a sphere is attracted by the Moon and the Sun by forces directed to its center. For this reason, the Earth's axis remains unchanged. This attraction, acting on the equatorial swelling, tends to turn the Earth in such a way that the planes of the earth's equator and the object attracting it coincide, creating a tipping moment.
If the Earth did not rotate, it would tend to bend, as if nodding, so that the equator always watched the Sun and the Moon.
The Earth moves around the Sun in orbit,which is almost similar to a circle. Observation of the speed of stars located near the ecliptic, represents that at any moment we are approaching one of the stars and moving away from them in the sky at a speed of 29.5 kilometers per hour. The change of seasons is the result of that. There is a tilt of the earth's axis to the plane of the orbit and is about 66.5 degrees.
Due to a small elliptical orbit, the planet in January is somewhat closer to the Sun than in July, but the difference in distance is not significant. Therefore, the effect on obtaining heat from our star is hardly noticeable.
The present angle of the earth's axis in relation toplane of the orbit is 66.5 ° and provides not so sharp fluctuations in winter-summer temperatures. For example, if this angle was about 45 °, what would happen at the latitude of Moscow (55.5 °)? In May, the sun under these conditions will reach zenith (90 °) and will shift to 100 ° (55.5 ° + 45 ° = 100.5 °).
With such intensive movement of the Sun, the springthe period would pass much faster, and in May it would reach a peak of temperatures, as at the equator at the maximum solstice. Then it would be slightly weakened, since the sun, passing the zenith, would go a little further. Then he returned back, passing the zenith again. Within two months, in July and May, there would be an unbearable heat, about 45-50 degrees Celsius.
Now consider what would happen with the winter, toexample, in Moscow? After passing the second zenith, our luminary would have sunk in December to 10 degrees (55.5 ° -45 ° = 10.5 °) above the horizon. That is, with the approach of December, the sun would have appeared for a shorter period than now, rising slowly above the horizon. During this period, the sun would shine for 1-2 hours a day. Under such conditions, the night temperature will drop below -50 degrees Celsius.
As we see, for the climate on the planet is important,at what angle the earth's axis. This is a fundamental phenomenon in the soft climate and living conditions. Although, perhaps under different conditions on the planet, evolution would have gone a different way, creating new species of animals. And life would continue to exist in another of its diversity, and, perhaps, there would be a place for "another" person in it.