How the earth's magnetic field works. Theory of the Earth's magnetic field: mechanism of occurrence, structure, magnetic storms, polarization reversal

Why you need the Earth's magnetic field, you will learn from this article.

What is the value of the earth's magnetic field?

First of all, it protects artificial satellites and the inhabitants of the planet from the action of particles from space. These include charged, ionized particles of the solar wind. When they enter our atmosphere, the magnetic field changes their trajectory and directs them along the field line.

In addition, we entered the era of new technologies thanks to our magnetic field. All modern, advanced devices that work using a variety of memory drives (disks, cards) depend directly on the magnetic field. Its tension and stability directly affects absolutely all information, computer systems, since all the information necessary for their proper operation is placed on magnetic media.

Therefore, we can say with confidence that the prosperity of modern civilization, the "viability" of its technologies closely depends on the state of the magnetic field of our planet.

What is the earth's magnetic field?

Earth's magnetic field is an area around the planet where magnetic forces act.

As for its origin, this issue has not yet been finally resolved. But most researchers are inclined to believe that our planet owes the presence of a magnetic field to the core. It consists of an inner solid part and an outer liquid part. The rotation of the Earth contributes to constant currents in the liquid core. And this leads to the emergence of a magnetic field around them.

Most of the planets in the solar system have magnetic fields to varying degrees. If you place them in a row according to the decrease in the dipole magnetic moment, you get the following picture: Jupiter, Saturn, Earth, Mercury and Mars. The main reason for its occurrence is the presence of a liquid core.

The earth is a giant magnet around which a magnetic field forms. The magnetic poles of the Earth do not coincide with the true geographic poles - north and south. The lines of force that run from one magnetic pole to another are called magnetic meridians. A certain angle is formed between the magnetic and geographic meridians (about 11.5 ° - approx .. Therefore, the magnetized compass needle accurately shows the direction of the magnetic meridians, and the direction to the north geographic pole is only approximately.

A freely suspended magnetic needle is located horizontally only on the line of the magnetic equator, which does not coincide with the geographic one. If you move north of the magnetic equator, then the northern end of the arrow will gradually drop. The angle formed by the magnetic needle and the horizontal plane is called the magnetic inclination. At the North Magnetic Pole (77° N and 102° W), a freely suspended magnetic needle will be installed vertically with the north end down, and at the South Magnetic Pole (65° S and 139° E - note .. Thus, the magnetic needle shows the direction of the magnetic field lines above the earth's surface.

It is believed that our planet itself generates a constant magnetic field. It is formed due to a complex system of electrical currents that occur during the rotation of the Earth and the movement of liquid matter in its outer core. The position of the magnetic poles and the distribution of the magnetic field over the earth's surface change over time. The Earth's magnetic field extends to a height of about 100,000 km. It deflects or captures solar wind particles that are harmful to all living organisms. These charged particles form the Earth's radiation belt, and the entire region of near-Earth space in which they are located is called the magnetosphere.

The sun sends a huge stream of energy to the Earth, consisting of electromagnetic radiation (visible light, infrared and radio radiation - approx.); ultraviolet and x-ray radiation; solar cosmic rays, which appear only during very strong flares; and the solar wind - a constant stream of plasma formed mainly by protons (hydrogen ions).

The electromagnetic radiation of the Sun comes to the Earth in 8 minutes, and the particle streams, which bring the main part of the perturbation from the Sun, move at a speed of about 1000 km/s and are delayed for two or three days. The main cause of solar wind disturbances, which significantly affect terrestrial processes, are the grandiose ejections of matter from the solar corona. When moving towards the Earth, they turn into magnetic clouds and lead to strong, sometimes extreme disturbances on the Earth. Especially strong perturbations of the Earth's magnetic field - magnetic storms - disrupt radio communications and cause intense auroras.

Aurora Borealis over Earth (viewed from space)

Magnetic anomalies

In some regions of the planet, deviations of the magnetic declination and magnetic inclination from the average values ​​for a given territory are observed. For example, in the Kursk region, in the region of an iron ore deposit, the magnetic field strength is 5 times higher than the average for this region. The field is called so - the Kursk magnetic anomaly - note .. Sometimes such deviations are observed over vast areas. The East Siberian magnetic anomaly is characterized by a western magnetic declination, not an eastern one.

A message on the topic: "Magnetic field" will help you prepare for classes and expand your knowledge about this unique phenomenon.

Message "Magnetic Field"

A little about the history of the study of the force field. William Gilbert, an English scientist, published a book in 1600 entitled "On the Magnet, Magnetic Bodies, and the Great Magnet, the Earth." In it, he depicted the Earth as a permanent giant magnet with its own axis, which is different from the axis of rotation of the planet. Today, this angle of deviation is called magnetic declination.

In addition, Hilbert confirmed his assumption experimentally. They carved a large ball from a natural magnet. Bringing the magnetic needle closer to the ball, he proved that it is always set in the same way as the arrow on the compass. That is, the scientist concluded that the magnetic field of our planet is similar to a similar field of a permanent magnet.

And in 1702, another scientist E. Halley created the world's first magnetic maps of the Earth.

What is the reason why the Earth has a magnetic field? It's all about its core, which is a red-hot iron - it is an excellent conductor for electric currents that arise inside the planet. By itself, it forms a magnetosphere that extends for 80,000. The magnetosphere protects the Earth's surface from cosmic rays, charged particles, high energies, forming a screen. In addition, it affects the nature of the weather.

Are there changes in the Earth's magnetic field?

Back in 1635, the scientist Gellibrand established that the planet's magnetic field is changeable. A little later, it was established that these changes are short-term and permanent.

The reason for the constant change is the deposits of minerals. For example, there are territories on the planet where deposits of iron ores strongly distort the Earth's magnetic field (Kursk magnetic anomaly). The reason for short-term changes is the effect of the "solar wind", that is, the flow of charged particles that the Sun throws out. This is how magnetic storms occur.

The influence of the magnetic force field on living organisms

The magnetic field of our planet helps many animals to navigate in space. For example, marine bacteria prefer to settle only at an angle with respect to field lines. This is due to the fact that in their body there are small ferromagnetic particles. But insects are located exclusively in the direction either along or across the magnetic lines.

Migratory birds also navigate by the Earth's magnetic field. Scientists have recently learned an amazing fact: in the area of ​​\u200b\u200btheir eyes there is a small tissue field, a kind of compass, in which magnetite crystals are located. They have the ability to be magnetized in a magnetic field, thereby orienting themselves in space. It has also been shown to affect plant growth.

We hope that the report "Magnetic Field of the Earth" helped you prepare for the classes. And you can leave your message about the magnetic field through the comment form below.

In the last century, various scientists have put forward several assumptions about the Earth's magnetic field. According to one of them, the field appears as a result of the rotation of the planet around its axis.

It is based on the curious Barnet-Einstein effect, which lies in the fact that when any body rotates, a magnetic field arises. The atoms in this effect have their own magnetic moment, as they rotate around their own axis. This is how the Earth's magnetic field appears. However, this hypothesis did not withstand experimental tests. It turned out that the magnetic field obtained in such a non-trivial way is several million times weaker than the real one.

Another hypothesis is based on the appearance of a magnetic field due to the circular motion of charged particles (electrons) on the surface of the planet. She, too, was incompetent. The movement of electrons can cause the appearance of a very weak field, moreover, this hypothesis does not explain the reversal of the Earth's magnetic field. It is known that the north magnetic pole does not coincide with the north geographical.

Solar wind and mantle currents

The mechanism of formation of the magnetic field of the Earth and other planets of the solar system is not fully understood and so far remains a mystery to scientists. However, one proposed hypothesis does a pretty good job of explaining the inversion and magnitude of the real field induction. It is based on the work of the internal currents of the Earth and the solar wind.

The internal currents of the Earth flow in the mantle, which consists of substances with very good conductivity. The core is the current source. Energy from the core to the earth's surface is transferred by convection. Thus, in the mantle there is a constant movement of matter, which forms a magnetic field according to the well-known law of motion of charged particles. If we associate its appearance only with internal currents, it turns out that all planets whose direction of rotation coincides with the direction of rotation of the Earth must have an identical magnetic field. However, it is not. Jupiter's north geographic pole coincides with the north magnetic.

Not only internal currents are involved in the formation of the Earth's magnetic field. It has long been known that it reacts to the solar wind, a stream of high-energy particles coming from the Sun as a result of reactions occurring on its surface.

The solar wind by its nature is an electric current (the movement of charged particles). Entrained by the rotation of the Earth, it creates a circular current, which leads to the appearance of the Earth's magnetic field.