Earth's magnetic poles will remain in place soon

Scientists have long discovered that the magnetic poles of our planet are relatively frequently interchanged. The magnetic south pole becomes north and vice versa. Such changes in the past have happened repeatedly, and experts believe that the inversion will continue in the future. The last "substitution" occurred about 800 thousand years ago. Since the beginning of observations of the dynamics of the Earth’s magnetic field, scientists have noted a slight shift in the north and south magnetic poles and a slight change in the configuration of the field itself. Does this mean the beginning of a new period of displacement? Probably not.

An international team of researchers studied inversions that happened millions of years ago. The periods between the changes were also analyzed. Conclusion - now a little portendsthe next cycle of "changing of the guard" with poles, people can sleep peacefully.

But how can one even understand what happened there with the poles millions of years ago? To do this, it is necessary to study volcanic rocks. During their formation, the Earth's magnetic field affects the magnetic particles inside the rocks. They get a kind of “magnetic signature”, fixing the configuration of the Earth’s field at the time of its formation. By the way, heating the rocks to a certain level removes the “residual” configuration, reducing it to the current position of the poles.

Earth's magnetic field is heterogeneous. In some regions it is stronger, in others - weaker. In order to obtain a single configuration of the planet’s magnetic field, scientists need to analyze a lot of data, which are then reduced to a global model.

So, after studying various rock samples, it turned out that in the period from 30,000 to 50,000 years ago, the Earth’s magnetic poles changed in an unusual way. Generally speaking, when the polarity changes, the lines of force of the magnetic field of our planet first take a complex shape, and the magnetic field itself weakens - up to 10% of the original value. At the same time, additional poles form, some of which can shift towards the equator.

As it turned out, a very short-term (by geological standards) polarity reversal occurred 41 thousand years ago. This event was called the "Lachamp event" , it lasted less than a thousand years. Over the course of 250 years, the direction of the planet’s magnetic field also changed.

All this is interesting, but what does the “Lachamp event” or magnetic inversion of 800-year-old magnetic poles have to do with modernity? The good news is that there is no - that is, the modern configuration of the magnetic field in no way resembles what it was thousands of years ago. Yes, there is a slight weakening of the planet’s magnetic field, but the general configuration of the lines of this field does not change, in addition, there are no signs of the possible appearance of additional poles. And this, as scientists have found, the main signs of an imminent pole change.

The weakening of the Earth's magnetic field has already taken place in the past. The cases closest to us are 48,500 and 46,300 years ago. In the first case, the magnetic field in the southern hemisphere weakened, in the second, a similar phenomenon occurred near South America. But there were no additional poles, changes in the magnetic field vector or pole changes; gradually, the characteristics straightened to previous values ​​or parameters close to them.

The authors of the study in question believe that the forerunners of inversion are not only the weakening of the Earth's magnetic field, but also many other factors that are not there right now.

If everything is as scientists say, then this is really good news. The fact is that it is the lines of the planet’s magnetic field that protect the Earth from hard cosmic radiation. If inversion had happened in our time, this would have led to numerous equipment malfunctions, from near-Earth satellites to electronic devices on the surface of the Earth. In addition, this kind of radiation is harmful to living organisms. Probably, the global economy would lose tens and hundreds of billions of US dollars, problems would begin in society - wars, famines and the like "satellites" of the crisis.

Interestingly, scientists still do not know exactly why the Earth's magnetic field exists. In our system, besides it, Mercury, the Earth, four gas giants and Ganymede have a magnetic field. Most likely, the magnetic field is generated by a metal core in the center of the planet (in the case of the Earth) with a relatively solid center and a liquid shell. The theory of magnetic field generation by the core is called the magnetic dynamo . It is generally accepted, but this does not mean that it has no shortcomings. The fact is that over time, the dynamo effect should fade, and the core of the planet should gradually cool.

DOI: 10.1073 / pnas.1722110115