Precession is ... Precession of the Earth's axis: a description and interesting facts

Nearly four million people in the worldyears, and during this time we have reached an understanding of the motion of tectonic plates, have learned to predict the weather and have mastered outer space. But our planet is fraught with a lot of secrets and mysteries. One of them, which is associated with global warming and the theory of catastrophes, is the precession of the axis of the planet.

Historical essay

Movement of the equinox points against the starsnoticed in the III century BC Aristarchus of Samos. But the first described the increase in the longitude of stars and the difference between the star and actual year of the ancient Greek astronomer Hipparchus in the II century BC. And this despite the fact that at that time it was believed that all the stars are fixed on a stationary sphere, and the movement of the sky is the movement of this sphere around its own axis. Afterwards there were the works of Ptolemy, Theon of Alexandria, Sabit ibn Kurra, Nicholas Copernicus, Tycho Brahe and many others. The cause of the precession of the Earth's axis was explained and described by Isaac Newton in his "Beginnings" (1686). And the American astronomer Simon Newcom (1896) showed the precession formula. It was his formula, specified in 1976 by the International Astronomical Union, that describes the rate of precession, depending on the timing.

Physics of the phenomenon

In elementary physics, precession is a changethe angular momentum of a body with a change in its direction of motion in space. Observe this process by the example of a top and its slowing down. Initially, the vertical axis of the top when it slows down begins to describe the cone - this is the precession of the axis of the top. The main physical property of precession is inertialess. This means that when the force that causes precession ceases, the body will stand still. With respect to celestial bodies, gravity is such a force. And since it acts constantly, the movement and precessing of the planets will never cease.

The motion of our motionless planet

Everyone knows that the planet Earth rotatesaround the Sun, makes a rotation on its axis and changes the direction of this axis. But that's not all. Astronomy distinguishes thirteen kinds of movement of our house. Let's enumerate them in brief:

• Rotation around its own axis (change of day and night).
• Rotation around the Sun (change of seasons).
• "Walking ahead" or anticipating the equinoxes is a precession.
• The rocking of the earth's axis is nutation.
• Change in the Earth's axis to the plane of its orbit (inclination of the ecliptic).
• Change in the ellipse of the Earth's orbit (eccentricity).
• Changes in perihelion (distance from the most distant from the sun of the orbit).
• Parallactic inequalities of the Sun (monthly changes in the distance between our planet and the luminary).
• At the time of the parade of planets (the planets are located on one side of the Sun), the center of mass of our system goes beyond the boundaries of the solar ball.
• Deviations of the Earth (perturbations and perturbations) under the influence of the attraction of other planets.
• Progressive movement of the entire solar system to Vega.
• The motion of the system around the nucleus of the Milky Way.
• Movement of the galaxy The Milky Way around the center of the cluster of the same galaxies.

All this is complicated, but mathematically proven. We will focus on the third movement of our planet - the precession.

Is this a yule?

We used to think that the axis of rotation of the planetaround its axis is unchanged and its northern end is directed to the point of the polar star. But it's not entirely true. The axis of the planet describes a cone, as well as a children's toy of a whirligig or a top, which is caused by the attraction of our companion and our luminary. As a result, the poles of the planet slowly move relative to stars with an arc radius of 23 degrees and 26 minutes.

How can I see this?

The inclination of the earth's axis is due tointeractions in the system of gravity the Sun-Earth and the Moon-other planets. Efforts of gravity are so great that they make the axis of the planet perform precession - slow rocking in the clockwise direction in the direction opposite to the rotation of the planet. To see the phenomenon of lunar-solar precession in action is easy - just look at the spinning top. If you reject his handle from the vertical, it begins to describe the circle in the opposite direction to the rotation. If we imagine that the axis of the planet is a pen, and the planet itself is a yule, then this will be a rough example of the precession of the Earth's axis. Half of the cycle of precession, our planet passes for 25776 years.

Consequences of the precession of the Sun and the Earth-Moon complex

The slow movement of the point of the vernal equinox (the intersection of the celestial equator and the ecliptic), provoked by precession, leads to two consequences:

• Adjusting the celestial coordinates.
• Changes in the presence of the Sun in the zodiacal constellations.

Changes in the vernal equinox led tothe emergence of an international agreement on the coordinates of celestial bodies with the obligatory fixation on a specific date. Indeed, due to the precession of the axis of the Earth in ancient times, this point was located in the constellation Aries, and today it is located in the constellation Pisces. By analogy, there is no correspondence between the astrological signs of the zodiacal constellations. For example, the sign of Pisces says that in the period from February 21 to March 21, the light is located in the constellation Pisces. So it was in ancient times. But today, due to the precession of the Earth's orbit during this period of time, the Sun is in the constellation of Aquarius.

There will be no eternal spring

Precession is a prelude to the equinoxes, whichmeans the shift of the points of the autumn and spring equinoxes. In other words, spring on the planet every year comes earlier (by 20 minutes and 24 seconds), and autumn later. This is irrelevant to the calendar - our Gregorian calendar takes into account the length of the tropical year (from equinox to equinox). Therefore, in fact, the precession effect is already included in our calendar. This shift is periodic, and its period, as already mentioned, is 25776 years.

When will the new Ice Age come?

Changing the direction of the axis of the Earth every approximately26 thousand years (precession) is a change in its northern direction. Today the point of the North Pole points to the Polar Star, in 13 thousand years it will point to Vega. And in 50 thousand years the planet will go through two cycles of precession and return to its present state. When the planet is located "directly" - the amount of solar energy received is minimal and the ice age begins - most of the land covers ice and snow. The history of the planet shows that the glacial period lasts about 100 thousand years, and the interglacial period lasts 10 thousand. Today we are experiencing such an interglacial time, but after 50 thousand years the ice crust will cover the planet to the borders below New York.

Not only the precession is to blame

According to the National AerospaceAgencies NASA, the geographical North Pole of the planet since 2000 began to actively move to the east. Over 115 years of studying the climate on the planet, he deviated by 12 meters. Until 2000, the pole moved at a speed of several centimeters per year towards Canada. But after that date, he changed both direction and speed. Today, at a speed of up to 17 centimeters per year, it is moving towards Britain. The causes of this phenomenon are the melting of the Greenland glaciers, an increase in the mass of ice in the east of Antarctica, and droughts in the Caspian and Hindustan basins. And behind these phenomena is an anthropogenic factor influencing the Earth.

Why are winters different?

Besides the fact that our planet is precessing, italso oscillates with this process. This nutation is fast with respect to the precessional period of “swinging the poles”. It is she who changes the weather - then winter is colder, then summer is drier and hotter. In years of particularly strong nutation, more severe weather conditions are expected.