Mankind has almost four million years behind us, and during this time we have reached an understanding of the movement of tectonic plates, learned to predict the weather and mastered outer space. But our planet is still fraught with many secrets and mysteries. One of them, which is associated with global warming and catastrophe theory, is the precession of the planet axis.
Historical essay
The movement of the equinoxes against the background of the stars was noticed in the 3rd century BC by Aristarchus of Samos. But the first to describe the increase in the longitude of stars and the differences between the stellar and the actual year, 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 fixed sphere, and the movement of the sky is the movement of this sphere around its own axis. After there were works by Ptolemy, Theon of Alexandria, Sabit ibn Kurr, Nikolai Copernicus, Tycho Brahe and many others. The reason for the precession of the axis of the Earth was explained and described by Isaac Newton in his "Principles" (1686). And the formula for the precession was shown by the American astronomer Simon Newcom (1896). It is his formula, refined in 1976 by the International Astronomical Union, that describes the precession rate depending on the time reference.
Physics of the phenomenon
In elementary physics, precession is a change in the angular momentum of a body when its direction of motion in space changes. This process is observed on the example of a top and its slowdown. Initially, the vertical axis of the top when it slows down begins to describe the cone - this is the precession of the top of the top. The main physical property of precession is inertia. This means that when the force causing the precession ceases, the body will take a fixed position. For celestial bodies, gravity is such a force. And since it acts constantly, then the movement and precession of the planets will never stop.
The motion of our motionless planet
Everyone knows that the planet Earth revolves around the Sun, rotates on its axis and changes the direction of this axis. But that's not all. Astronomy distinguishes thirteen types of movement of our home. We list them briefly:
- Rotation around its own axis (change of day and night).
- Rotation around the Sun (change of seasons).
- “Going forward,” or preceding the equinoxes, is a precession.
- The wiggle of the earth's axis is nutation.
- Change of 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 point of orbit farthest from the sun).
- 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 globe.
- Earth deviations (disturbances and perturbations) due to the attraction of other planets.
- The progressive movement of the entire solar system towards Vega.
- The movement of the system around the core of the Milky Way.
- The movement of the Milky Way galaxy 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 - precession.
Is it yule?
We are used to thinking that the axis of rotation of the planet around its axis is unchanged and its northern end is directed to the point of the polar star. But this is not quite so. The axis of the planet describes a cone, as well as a children's toy or a spinning top, which is caused by the attraction of our satellite and our luminary. As a result, the poles of the planet slowly move relative to the stars with an arc radius of 23 degrees and 26 minutes.
How to see it?
The inclination of the earth's axis is due to interactions in the gravity system of the Sun-Earth and the Moon-other planets. The gravitational forces are so great that they force the axis of the planet to make a precession - slowly wiggle clockwise in the opposite direction to the rotation of the planet. It is easy to see the phenomenon of the lunar-solar precession in action - just look at the wound top. If you reject his pen from the vertical, then it begins to describe the circle in the opposite direction of rotation. If you imagine that the axis of the planet is a pen, and the planet itself is yule, then this will be a rough but an example of the precession of the axis of the Earth. Half the cycle of precession, our planet passes in 25776 years.
The consequences of the precessions of the Sun and the Earth-Moon complex
The slow movement of the vernal equinox (the intersection of the celestial equator and the ecliptic), provoked by precession, leads to two consequences:
- Correcting celestial coordinates.
- Changes in the stay of the Sun in the zodiac constellations.
Changes in the vernal equinox led to the emergence of an international agreement on the coordinates of celestial bodies with mandatory fixation on a specific date. Indeed, due to the precession of the axis of the Earth in ancient times, this point was in the constellation Aries, and today it is located in the constellation Pisces. By analogy, there is no correspondence between astrological signs of the zodiac constellations. For example, the sign of Pisces indicates that in the period from February 21 to March 21 the star 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 Aquarius.
There will be no eternal spring
Precession is the preceding of the equinoxes, which means the displacement of the points of the autumn and spring equinoxes. In other words, spring on the planet comes earlier every year (20 minutes and 24 seconds), and autumn later. This has nothing to do with the calendar - our Gregorian calendar takes into account the length of the tropical year (from the equinox to the equinox). Therefore, in fact, the precession effect is already included in our calendar. This displacement is periodic, and its period, as already mentioned, is 25776 years.
When will the new Ice Age come?
A change in the direction of the Earth's axis every approximately 26 thousand years (precession) is a change in its northern direction. Today, the North Pole point indicates the North Star, after 13 thousand years it will point to Vega. And after 50 thousand years, the planet will undergo two cycles of precession and return to its current state. When the planet is located “directly” - the amount of solar energy received is minimal and the ice age sets in - ice and snow cover most of the land. The history of the planet shows that the ice age lasts about 100 thousand years, and the interglacial - 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 is the precession to blame
According to NASA's National Aerospace Agency, the geographic North Pole of the planet has been actively shifting east since 2000. For 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 in the direction of Canada. But after the specified date, he changed both direction and speed. Today it is moving up to Britain at a speed of up to 17 centimeters per year. 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 the anthropogenic factor affecting the Earth.
Why are winters different?
Besides the fact that our planet is precessing, it also oscillates during this process. This nutation is fast relative to the precession period of the “pole wobble." It is she who changes the weather - winter is colder, summer is drier and hotter. In years of especially strong nutation, more severe weather conditions are expected.