Scientists have puzzled over the causes of the Earth's magnetic field for many years. The answer to this question was received quite recently. It turned out that certain conditions are necessary for the formation of a magnetic field.
Some hypotheses about the origin of the Earth's magnetic field
In the last century, various scientists have put forward several assumptions about how the Earth's magnetic field is formed. 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 Barnett-Einstein effect, which is that when any body rotates, a magnetic field arises. The atoms in this effect have their own magnetic moment, as they rotate around their axis. This is how the Earth's magnetic field appears. However, this hypothesis did not stand up to experimental tests. It turned out that the magnetic field obtained in such a nontrivial 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 planet's surface. It also turned out to be untenable. The movement of electrons can cause the appearance of a very weak field, moreover, this hypothesis does not explain the inversion of the Earth's magnetic field. It is known that the north magnetic pole does not coincide with the geographic north.
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. Nevertheless, one proposed hypothesis explains quite well the inversion and the magnitude of the induction of the real field. It is based on the work of the internal currents of the Earth and the solar wind.
Internal currents of the Earth flow in the mantle, which consists of substances with very good conductivity. The source of the current is the nucleus. Energy is transferred from the core to the surface of the earth by convection. Thus, a constant movement of matter is observed in the mantle, 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 geographic north pole coincides with the north magnetic pole.
Not only internal currents are involved in the formation of the Earth's magnetic field. It has long been known to react to the solar wind, a stream of high-energy particles emanating from the Sun as a result of reactions occurring on its surface.
The solar wind is by its nature an electric current (movement of charged particles). Being carried away by the rotation of the Earth, it creates a circular current, which leads to the appearance of the Earth's magnetic field.
