The Earth's magnetosphere does not just endow our planet with northern and southern magnetic poles. It also protects us from solar wind and cosmic radiation. However, this invisible force is rapidly weakening. And so much so that scientists even begin to say that after a while the magnetic field can roll over, and the poles of the planet will be reversed.
As insane as it may sound, this has happened before. The last time the inversion occurred was about 780,000 years ago and, according to some scientists, it could happen again in about 40,000 years. With the latter, scientists are not sure, and it is this uncertainty that makes one look for answers. At the same time, researchers say that even if this reversal of polarity does occur in the future, it will not occur quickly, but for several thousand years.
Of particular interest to scientists at the moment is the so-called South Atlantic anomaly ( SAA) – a huge area of the magnetic field of the planet, stretching from Chile to Zimbabwe. It is this phenomenon, according to scientists, now makes the magnetic field of the Earth weaken. Here, its strength is so weak that it poses a threat to orbiting satellites that can pass through it. About the work the researchers shared in the journal Geophysical Review Letters.
Imagine that the Earth's magnetosphere is the peel of an orange. Everything that is under this skin is protected from harmful influences from outside. AAA, in turn, is a deep dent on this peel. All satellites in the Earth's low Earth orbit are also under the skin, but, passing through the AAA (a dent on the skin), they come out from under her protection, and their electronics become defenseless before the destructive flows from outer space. That's why all the devices suspend their work, flying over the SAA.
"We have known for a long time that a magnetic field in this region is changing. But we did not know if this was always the case for this region or this particular phenomenon, "says physicist Vincent Hare of the University of Rochester (USA).
One of the reasons why scientists know little about the history of the magnetic field in this region of the Earth , is the lack of archaeomagnetic data – physical evidence about the Earth's magnetism, which could be preserved in archaeological relics of the past.
Nevertheless, one such evidence from the past has been preserved, and it is related to the ancient African people who lived in the INE Limpopo River, extending to areas of Zimbabwe, South Africa and Botswana -. regions, currently located inside the South Atlantic anomaly
Life in Africa has always been difficult. But about 1000 years ago, when residents of these places encountered special environmental difficulties, they performed sacred rituals. In times of especially droughty seasons, people burned their clay dwellings and grain storehouses, thus trying to appease the gods and convince them to give long-awaited rains. Certainly, these ancient Africans did not even suspect that with their rites they would create an invaluable ground for scientific research for those who will live several centuries after them.
Clay, like everything that exists on Earth, has a pronounced energy and has its own information field , which, among other things, can contain information about the magnetic field of the planet.
"When you heat the clay to a certain temperature, you actually stabilize the magnetic minerals contained in it. In these minerals, "printed" information about the magnetic field is erased and overwritten with data on the current state of the field, "explains geophysicist John Tarduno.
In other words, analyzing these clay artifacts allows scientists not only to find out more about the culturological characteristics of ancient peoples living thousands years ago in South Africa, but also to learn what the Earth's magnetic field was at that time.
"We were looking for signs of recurring behavior, because we believe that they are the existence of the South Atlantic anomaly today. And we really found them. This information helps us to contextualize current changes in the magnetic field, "says Tarduno.
The study showed that the current weakening in the SAA is not a separate phenomenon in the history of the Earth, but has occurred several times in the past. Analogous changes, say scientists, were to be observed in 400-450 gg. n. e., 700-750 years. n. e., and also in 1225-1550. n. e. And this information indicates that the location of the South Atlantic anomaly is not a mere geographical accident.
"We are starting to get convincing evidence that Africa has something unusual. Something that can have an important influence on the general state of the earth's magnetic field, "adds Traduno.
There is an assumption that the weakening of the planet's magnetic field, observed for about the last 160 years, is caused by so-called" African low-speed mantle provinces "or African superplumes (hot mantle streams moving from the base of the mantle to the core of the Earth, regardless of the convective currents in the mantle), located at a depth of about 2900 kilometers under the African continent.
"This geological feature should be several tens of millions of years. It stretches for thousands of kilometers, but it has very distinct boundaries, "scientists say.
These dense streams exist in the boundary layer between the mantle and the core of the planet and, according to some assumptions, can somehow cause perturbations of the inland sources that generate. But before we can know everything for sure, it will take more than a dozen large-scale scientific researches.
Experts say that, according to the idea of a pole shift, the process that takes place directly in the very core of the planet will begin, but the results The last study suggests that everything that happens to the magnetic field around the Earth is strongly associated with phenomena occurring in certain areas of the boundary region between the core and the mantle. If this is true, then hardly anyone would have thought that we would be obliged to solve this complex puzzle by the usual ancient ritual practiced a millennium ago. Nevertheless, scientists are not yet ready to give an answer to the question of what all this means for our future.
"Now we know that these changes in the magnetic field have occurred several times in the past. And the last of them is observed the last 160 years. Proceeding from this, it can be concluded that all these events are part of one whole, something more, "say the researchers.
" But it is too early to say whether these changes will really lead to a change in the poles of the planet "