Researchers believe that the movement of liquid metal at the Earth's core is one of the main causes of magnetic pole reversal.

Earth, a rocky planet containing liquid water, is an ideal place for life to thrive for many reasons. Earth is located at the right distance from its star for liquid water to exist on the planet's surface. The gravity of other planets protects Earth from the risk of collisions with wandering asteroids. The magnetic field surrounding the Earth also provides a barrier that protects life from charged particles shooting through space, according to Space.

Earth's magnetic field is created by complex flows of molten metallic material in the planet's outer core. This flow of matter is influenced by both the Earth's rotation and the existence of a solid iron core. The result is a bipolar magnetic field whose axis is aligned with the planet's axis of rotation. Hidden in the chemical composition of ancient rocks is evidence that Earth's magnetic field is a dynamically changing phenomenon. As the lava cools, the iron minerals in it align with the Earth's magnetic field, similar to a compass needle pointing north.

The Earth's magnetic field changes over very short and extremely long time periods, from a few milliseconds to several million years. Interactions of the magnetic field with charged particles in the universe can change it over short periods of time, whereas longer-term magnetic field disturbances are caused by processes in the Earth's liquid outer core.

Under the influence of fluid movement inside the Earth, the reversal process of the geomagnetic field can be divided into three stages. In the decay stage of the magnetic field, the strength of the magnetic field will gradually weaken and its direction will become more chaotic. Next, magnetic pole drift is the process in which the Earth's magnetic poles begin to deviate from their current position and move in the opposite direction. The magnetic pole regeneration process is the stage where a new magnetic field begins to be established, the magnetic poles eventually reach a position opposite to the previous one.

Research into the past state of the magnetic field shows that two polarization states can exist. In the current normal state, magnetic field lines go out from the North pole and enter the South pole. Polarity reversal is also possible and equally stable. Paleogeomagnetic research shows that the phenomenon of reversal of the Earth's magnetic field is not periodic and unpredictable, mainly due to the mechanism that creates it. According to geophysicist Leonardo Sagnotti, the flow of liquid metal (mostly molten iron) in the Earth's outer core is very chaotic and changes erratically. Magnetic pole reversal occurs during periods of low geomagnetic field intensity and unstable magnetic field structure.

The period of magnetic pole reversal lasted several thousand years. When the magnetic field is about to reverse polarity, it is in a weakened state, leading to more exposure of the Earth's atmosphere to solar wind and cosmic rays in the form of charged particles. Recent research shows that during the Laschamps magnetic pole reversal event 41,000 years ago, the amount of cosmic rays reaching the Earth's atmosphere globally was three times higher than today.

For human civilization, what is worrying is not the change of magnetic poles but the period of decreasing geomagnetic field intensity. Modern society increasingly depends on technology. Large numbers of charged particles entering the magnetosphere at altitudes closer to the ground will affect security, communications, electrical infrastructure, satellites and astronauts living in low Earth orbit. In particular, due to the random nature of magnetic field fluctuations, researchers cannot predict exactly when this will happen.

Why does Earth's magnetic field reverse?

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