The earth's axis of our planet in the northern vector is directed to the point where the star of the second magnitude, called the Polaris, is located in the tail part of the constellation Ursa Minor.
This star traces a small circle on the celestial sphere with a radius of about 50 minutes of arc during the day.
In ancient times, they knew about the tilt of the earth's axis
Very long time ago, in the II century BC. e., the astronomer Hipparchus discovered that this point is mobile in the starry sky and slowly moves towards the movement of the Sun.
He calculated the rate of this movement at 1° per century. This discovery was called "precession of the earth's axis." This is the move ahead, or the prelude to the equinox. The exact value of this movement, the constant precession, is 50 seconds per year. Based on this, a full cycle along the ecliptic will be approximately 26,000 years.
Precision is important for science
Let's get back to the question of the pole. Determining its exact position among the stars is one of the most important tasks of astrometry, which deals with measuring arcs and angles on the celestial sphere in order to determine the coordinates of stars andplanets, proper motions and distances to the stars, as well as solving problems of practical astronomy, important for geography, geodesy and navigation.
You can find the position of the pole of the world using a photograph. Imagine a long-focus photographic camera, implemented in the form of an astrograph, aimed motionlessly at a region of the sky 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.
A little about the angle of the Earth's axis
The plane of the celestial equator, being perpendicular 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 Moon's attraction of the equatorial displacement of the Earth's masses tends to rotate the Earth in such a way that its equatorial plane intersects the Moon. But in this case, these forces act not on the water shell of the Earth, but on the masses that form the equatorial swelling of its ellipsoidal figure.
Let's imagine a sphere inscribed in the earth's ellipsoid, which it touches at the poles. Such a ball is attracted by the Moon and the Sun by forces directed towards its center. For this reason, the earth's axis remains unchanged. This attraction, acting on the equatorial bulge, tends to rotate the Earth in such a way that the planes of the earth's equator and the object attracting it coincide, thus creating an overturning moment.
The sun moves away fromequator to ± 23.5°, and the distance of the Moon from the equator during the month reaches almost ± 28.5°.
Children's toy top reveals a little secret
If the Earth did not rotate, then it would tend to tilt, as if nodding, so that the equator would follow the Sun and Moon all the time.
True, due to the huge mass and inertia of the Earth, such fluctuations would be very insignificant, since the Earth would not have time to react to such a rapid change in direction. We are well acquainted with this phenomenon on the example of a child's spinning top. The force of gravity tends to overturn the top, but the centripetal force prevents it from falling. As a result, the axis moves, describing a conical shape. And the faster the movement, the narrower the figure. The earth's axis behaves in the same way. This is a certain guarantee of its stable position in space.
The angle of the Earth's axis affects the climate
The Earth moves around the Sun in an orbit that is almost like a circle. Observation of the speed of stars located near the ecliptic represents that at any moment we are approaching some stars and moving away from the opposite ones in the sky at a speed of 29.5 kilometers per hour. The change of the seasons is the result of that. There is an inclination of the earth's axis to the plane of the orbit and is about 66.5 degrees.
Due to the small elliptical orbit, the planet is somewhat closer to the Sun in January than in July, but the difference in distance is not significant. Therefore, the effect on receiving heat from our starbarely noticeable.
Scientists believe that the earth's axis is an unstable parameter of our planet. Studies show that the angle of inclination of the earth's axis with respect to the plane of its orbit in the past was different and changed periodically. According to the legends that have come down to us about the death of Phaethon, in Plato's descriptions there is a mention of an axis shift at this terrible time by 28 °. This disaster took place over ten thousand years ago.
Let's dream a little and change the angle of the Earth
The current angle of the earth's axis with respect to the plane of the orbit is 66.5° and provides a not so sharp fluctuation in winter-summer temperatures. For example, if this angle were about 45°, what would happen at the latitude of Moscow (55.5°)? In May, under such conditions, the sun will reach the zenith (90°) and shift to 100° (55.5°+45°=100.5°).
With such an intense movement of the Sun, the spring period would pass much faster, and in May it would reach the peak of temperatures, as at the equator at maximum solstice. Then it would weaken slightly, as the sun, passing the zenith, would go a little further. Then it came back, passing the zenith again. For two months, in July and May, there would be unbearable heat, around 45-50 degrees Celsius.
Now consider what would happen to winter, for example, in Moscow? After passing the second zenith, our luminary would have dropped to 10 degrees (55.5°-45°=10.5°) above the horizon in December. That is, with the approach of December, the sun would go out moreshort time than now, rising low above the horizon. During this period, the sun would shine for 1-2 hours a day. Under such conditions, nighttime temperatures will drop below -50 degrees Celsius.
Each version of evolution has the right to life
As we see, for the climate on the planet it is important at what angle the earth's axis. This is a fundamental phenomenon in the mildness of the climate and living conditions. Although, perhaps, under different conditions on the planet, evolution would have gone in a slightly different way, creating new types of animals. And life would continue to exist in its other diversity, and, perhaps, there would be a place for a “different” person in it.
