It envelops everything on the planet, from the smallest magnets to our entire Earth, and is found even in space. Although we already know a lot about the magnetic field of our planet, it is still fraught with many mysteries and exhibits strange phenomena.
Recent discoveries have shown us especially clearly how little is known about geomagnetism and how these magnetic lines of force not only affect our brains, but are even involved in the creation of the legendary wormholes. Sometimes, somewhere far beyond the earth's atmosphere, magnetic fields create and then themselves solve very curious riddles ...
10 Magnetic Moths
Australian animals are some of the strangest creatures on the planet. And now this mainland nation can add the world's first magnetic moth to its list of curiosities. The outlandish species has been named the Agrotis infusa, or Bogon moth, and the creature is unique in that it is the first nocturnal insect to use the Earth's magnetic field during migration.
The discovery was made in 2018, and before it, scientists for a long time could not understand how exactly billions of such moles traveled a distance of almost 1,000 kilometers, and always returned to the same caves in the Australian states of New South Wales and Victoria (New South Wales, Victoria). As a result, the solution was found after experiments were carried out on several of these insects in special insulated rooms. It turned out that the Bogonian moth uses just a magnetic field for navigation, and it usually compares it with certain landmarks on the ground. If one of the conditions disappears, the insect goes astray and does not understand where to go.
This is a very interesting discovery, although it did not help scientists understand exactly how migratory birds and other animals that migrate over long distances use our planet's magnetosphere. According to one interesting theory, light rays affect certain abilities of birds at the quantum level. Birds are probably best magnetically oriented when their eyes perceive light. During daylight hours, an electrical signal appears in the bird's brain at the molecular level, which helps the animal to recognize the magnetic field. However, Bogonian moths are nocturnal, so their way of navigating probably works quite differently.
9. The epicenter of the reversal of the poles of the geomagnetic field
Photo: Live Science
The Earth's magnetic field is weakening and thinning, and it is now thinnest in the area between South Africa and Chile, for which this zone was even called the South Atlantic anomaly. The researchers decided to take a closer look at this region in the hope that there they will find a clue to the question of why, in general, the entire magnetic field of our planet began to weaken.
In 2018, experts discovered another anomaly, and this time it stretched from South Africa to Botswana. When people of the Iron Age built their clay houses here, when they were fired, the fire preserved magnetic minerals in the clay in such a way that it was possible to determine the state of the geomagnetic field of those years from these artifacts. Over the course of 1500 years, the electromagnetic field in this part of the world either thinned out, then completely changed its direction, then compressed, then protruded outward above the general scheme of field lines.
All these changes gave scientists reason to believe that the South Atlantic anomaly had occurred before, and each time it was a harbinger of a reversal of the poles of the Earth's magnetic field. If this is indeed the case, then an unusual area in the South African region may be the very place where these major changes will begin.
The current thinning of our planet's magnetic field can lead to 2 different scenarios. Either another polarity reversal will occur, or the field will condense again to prevent the change of vectors. The second option is much better, since a weak magnetic field is not able to protect us from strong ultraviolet radiation to a sufficient extent. Everything can start with regular power outages, which, if thinned, become too vulnerable to geomagnetic storms, and continue with much more unpleasant consequences.
8. Mystery of the bow shock wave
Photo: Live Science
The Earth revolves around the Sun at a speed of about 108,000 kilometers per hour. Just like the prow of a ship cutting through water in its path, our planet's magnetic field cuts us through the extremely hot solar wind constantly produced by our star.
For a long time, researchers believed that this bow shock around the Earth was the reason why the solar wind usually dissipates, reaching the surface of our home planet already as a gentle breeze, rather than a sizzling element. Without this mysterious process, our Earth would have been charred long ago. However, all the details of what is happening are still not fully understood.
In 2018, one very important discovery was probably made. It turns out that the Earth's magnetic field destroys the solar electrons. When scientists analyzed data from satellites collected in the zone of collision of the geomagnetic field and the solar field, they were amazed at how this field literally tears apart the stellar wind.
When the solar wind reaches the Earth's bow shock at supersonic speeds, the electrons are accelerated so much that they simply fall apart. As a result, the destructive energy of the solar wind is transformed into less dangerous heat.
7. New magnetic environment
Photo: space.com
The struggle between the solar wind and our magnetosphere does not fully save the Earth from solar radiation. The decay of stellar wind particles is definitely a big load for our magnetic field, and as a result, its lines of force are periodically broken. When one of these lines breaks, energy absorbed by the field from the solar wind is released, causing electrical grids, satellites and spacecraft to malfunction.
In 2018, scientists decided to conduct another study to learn more about the nature of this problem. As a result, they found out something completely new and absolutely amazing about magnetic activity. Previously, scientists have already noted that there is a special boundary between the solar wind and the magnetosphere. This zone is called the magnetosheath. However, the activity in this region was too high to determine whether the lines of our magnetic field in the same layer along with the solar electrons are being destroyed at the same time. With the help of several new satellites, scientists have confirmed that the process of reconnection (reconnection) also occurs in this magnetosheath.
When bonds are broken, the particles begin to move 40 times faster than in a conventional magnetic field. Researchers have discovered for the first time that two extremely important phenomena associated with charged solar particles occur in the same place.
6. Earth's magnetic field is shifting to the West
Photo: Live Science
Scientists have been observing the magnetic field of our planet for more than 400 years. The information collected over all this time has increasingly puzzled researchers who have long been struggling with one big riddle. For some reason inexplicable to us, the geomagnetic field is shifting westward.
In 2018, researchers proposed a new and very unusual answer to this question. Jet streams in water, air and even the core of the Earth create the so-called Rossby waves. The entire outer core of our planet is actually a constantly rotating liquid, and these waves circulate with it.
By their nature, these traveling waves are already considered a rather strange phenomenon, and the Rossby waves in the outer core behave absolutely differently from all other currents. Oceanic and atmospheric Rossby waves move westward, while waves in the outer core move eastward. Although scientists cannot accurately calculate the direction in which all this power is moving due to the significant depth at which these processes occur.
According to experts, despite the eastern orientation of the Rossby waves in the outer core of the Earth, most of their energy shifts to the west and pulls the magnetic field behind them. In any case, researchers still do not have a clear explanation why the geomagnetic field is shifting to the west at a speed of 17 kilometers per year.
5. Earth's second magnetic field
Photo: sciencealert.com
Once again, scientists were perplexed to discover something amazing that had been right in front of their noses for so long. It turns out that our planet is surrounded by as many as 2 magnetic fields. Most people know that our main magnetic field owes its existence to the processes taking place in the Earth's core. The second field was discovered quite by accident when the European Space Agency launched three new satellites into orbit to study geomagnetism.
After collecting data, the researchers discovered that our planet has another secret. For 4 whole years, scientists from the ESA analyzed the information received, until in 2018 they finally announced their amazing find to the whole world.
News of a second magnetic field has been hidden for so long because its tidal force is extremely small or almost imperceptible. If we compare it with the strength of the geomagnetic field known to us for a long time, it is weaker than it by as much as 20 thousand times.
In any case, the value of this discovery for scientists is extremely high, especially for those of them who have devoted their lives to the mysteries of geomagnetism. Each new detail completes the big picture, like a puzzle piece, and it may well help us explain other phenomena. For example, to answer the question of why the Earth's magnetic field periodically changes its poles, or how both magnetic fields affect each other. In addition, the new discovery could help scientists better understand the electrical properties of the lithosphere and the earth's crust.
4. The Mystery of the Pillars of Creation Revealed
Photo: ibtimes.com
In 1995, the Hubble Space Telescope spotted the so-called "Pillars of Creation", which became so famous that they were even printed on cup holders and shown in movies. The delightful image of columns of interstellar gas and dust shimmering in different colors clearly resembles giant pillars, and, as you know, new stars are born somewhere there.
This cluster is located 7 thousand light-years from Earth in the Eagle Nebula, and the mystery of the formation of these columns remained unsolved until 2018. New observations allowed scientists to detect a polarized glow emanating from, which betrayed the presence of a magnetic field there. When specialists were able to create a map of these fields, the origin of the famous trio was finally unraveled.
Magnetic forces slowed the spread of interstellar gas and cosmic dust within this nebula, and under their influence, these iconic columns were formed, recognizable almost all over the world. The imposing cosmic structure remains in its current form for a long time precisely because of the influence of magnetic fields, which actually protect the pillars from destruction by their tidal force, the vector of which is opposite to the direction of the external magnetic forces of the space surrounding this area. Given the fact that new stars are constantly being formed in the environment of the Pillars of Creation, understanding the nature of magnetism in their case may change the way scientists think about the process of star formation.
3. Uranus' magnetic field is constantly collapsing
Photo: space.com
When it comes to the magnetic field, Uranus has a hard time. In 2017, scientists wanted to study the magnetosphere of a fairly distant planet, and for this they used computer simulations and data obtained back in 1986 from NASA's Voyager 2 spacecraft (Voyager 2). As a result, we learned something unexpected about an already rather strange planet for us.
The orientation of Uranus in space differs from almost all other planets in the solar system in that its axis of rotation seems to lie on its side. Because of this, the planet's magnetic field is offset from the geometric center in a rather unusual way. A day on Uranus lasts 17.24 hours, and the magnetosphere of this planet is greatly overloaded in one revolution around its own axis. In some places, this magnetic field is almost completely destroyed, while in others reconnection occurs. This constant balancing just explains the frequent occurrence of auroras.
Data from the Hubble Space Telescope has previously confirmed that auroras are forming on Uranus, very similar to our terrestrial ones. The magnetosphere, as a rule, creates a protective block, and its thinning just causes the aurora. It seems that the appearance of gaps in its magnetic field is responsible for such a frequent occurrence of aurora on Uranus, and through these "holes" solar wind particles enter the planet's atmosphere, producing light shows upon contact with gases.
2. Magnetic molehill
Photo: Smithsonian Magazine
Physicists are constantly doing very strange experiments. In 2015, they created something completely incredible - a magnetic wormhole. Wormholes are a popular topic among sci-fi fans, but this time around, things can go a little further than theories and spectacular films. According to the well-known hypothesis, a wormhole is able to connect two different regions in the space-time continuum. Theoretically, with the help of such wormholes, a traveler is able to overcome simply incredible distances in a matter of fractions of a second.
In 2015, researchers developed a device that is a metal sphere made of several layers of metamaterial, which is unlikely to help us send space expeditions to the other end of the universe in the near future, but scientists have already created a magnetic wormhole with its help.
Inside this sphere, physicists placed a rolled-up magnetic tube, and then the whole device was hidden in another magnetosphere. At some point, the cylinder disappeared literally into nowhere, and then returned to its place again. He did not literally disappear, but simply became invisible to magnetic sensors.
What is interesting about this experiment is that during the manipulation of electromagnetic energy, a magnetically invisible tunnel was created between the interconnected poles of a magnet. This molehill created the illusion of separation of opposite poles and thanks to it, “monopoles” appeared, which simply do not exist in nature.
1. Control over the brain
Photo: Live Science
One of the most disturbing and unusual properties of the magnetic field is the ability to control the functioning of the brain with its help. In 2017, scientists conducted a study during which a new discovery was made. Using magnetic fields, the experts managed to remotely activate the brain cells of experimental mice.
The main target of exposure was the striatum, the part of the brain responsible for the movement of the animal. Incredibly, scientists made rats run, freeze in place and spin in place. The main interest for researchers is the ability to understand how the processes responsible for certain behavior and emotions take place in our head. This will likely tell us where the behavioral regions are located in the human brain and help treat conditions such as Parkinson's disease (tremor palsy).
If you are a conspiracy theorist and you are worried that the authorities will have complete control over us with the help of this discovery, you can breathe freely. Magnetic fields pass through biological tissues without any consequences. In the experiment, not the most ordinary rats took part, but animals with microscopic particles of magnets introduced into their brains. These particles were attached to brain cells, after which they were warmed up using a simulated magnetic field, and tiny magnets forced neurons to fire in such a way that the mouse changed its behavior according to a given scenario.
The earth is surrounded by a magnetic field. It is what keeps the compass needle pointing north and protects our atmosphere from the constant bombardment of charged particles from space, such as protons. Without a magnetic field, our atmosphere would slowly disappear under the influence of harmful radiation, and life would almost certainly not be able to exist in the form that we observe today.
You may think that the magnetic field is an infinite, constant aspect of life on Earth, and to some extent you would be right. But the Earth's magnetic field is actually changing. About once every few hundred thousand years or so, it flips over. The North Pole changes places with the South. And when this happens, the magnetic field also tends to become very weak.
Anomaly of the South Atlantic
Geophysicists are now alarmed by the realization that the strength of the Earth's magnetic field has been declining over the past 160 years at an alarming rate. This collapse is concentrated in a vast expanse of the southern hemisphere and extends from Zimbabwe to Chile. It is known as an anomaly of the South Atlantic. The strength of the magnetic field in this place is so weak that it even poses a danger to satellites that orbit the Earth over this area. The magnetic field no longer shields them from radiation that interferes with satellite electronics.
Consequences of the reversal of the magnetic field
But that is not all. The strength of the magnetic field continues to weaken, potentially heralding even more dramatic events, including a global reversal of the magnetic poles. Such a significant change will affect our navigation systems as well as power transmission. The Northern Lights can be seen at different latitudes. In addition, at very low field strengths, more radiation will reach the Earth's surface during the global roll, which can also affect cancer rates.
Scientists still do not fully understand the extent to which these effects will be achieved, so their research is especially relevant. They use some possibly unexpected sources of data, including 700 years of African archaeological records, to investigate the matter.
Origin of the Earth's magnetic field
The Earth's magnetic field is created by the presence of iron in the liquid outer core of our planet. Thanks to data from observatories and satellites that have recently studied the magnetic field, scientists can accurately model what it would look like if we placed a compass directly above the swirling liquid core of the Earth.
Reverse Polarity Spot
These analyzes reveal a striking feature: below southern Africa, there is a patch of reversed polarity at the core-mantle boundary where the liquid iron of the outer core meets the hard part of the Earth's interior. In this region, the polarity of the field is opposite to the average global magnetic field. If we could set up a compass deep under southern Africa, we would see that in this unusual area, the arrows that indicate north actually point south.
This slick is the main culprit in the anomaly in the South Atlantic. In numerical simulations, unusual patches similar to this have appeared just before geomagnetic reversals.
Throughout the history of the planet, the magnetic poles have changed quite often, but the last reversal occurred in the distant past, about 780 thousand years ago. Given the rapid decline in the strength of the magnetic field in the last 160 years, the question arises of what happened before.
The study of archeomagnetism
During archeomagnetic research, geophysicists and archaeologists try to learn about the past of the magnetic field. For example, clay that has been used to make pottery contains small amounts of magnetic minerals such as magnetite. When the clay was heated during the process of making pottery, its magnetic minerals lost the magnetism they may have had. When cooled, they recorded the direction and intensity of the magnetic field at that time. If the age of the pottery can be determined (using radiocarbon dating, for example), then there is also a chance to reconstruct the archeomagnetic history.
Through the use of this kind of data, scientists have a partial history of archeomagnetism for the Northern Hemisphere. In contrast, in the Southern Hemisphere these records are very scarce. In particular, there is virtually no data from South Africa, which, along with South America, could provide a better understanding of the history of the modern anomaly.
Archeomagnetic history of southern Africa
But the ancestors of modern South Africans, metallurgists and farmers who began to migrate to the region about 2000-1500 years ago, accidentally left us some clues. These Iron Age people lived in mud huts and stored grain in fortified mud bins. As the first Iron Age agronomists in southern Africa, they relied on rainfall.
These communities often responded to times of drought with cleansing rituals that entailed the burning of granaries. These somewhat tragic events for ancient people were ultimately a boon for the study of archeomagnetism. As with the firing and cooling of pottery, the clay in the granaries recorded the earth's magnetic field as it cooled. Since these ancient huts and grain bins are sometimes found intact, scientists can use them to get data on the direction and strength of the magnetic field at that time.
Scientists have focused their attention on sampling from the Iron Age sites that dot the valley of the Limpopo River.
Magnetic field flux
Sampling along the length of the Limpopo River provided the first data on the magnetic field of southern Africa between 1000 and 1600 AD. Scientists have found that around 1300, the strength of the magnetic field in this area was declining as rapidly as it is today. Then its intensity increased, albeit at a slower pace.
The appearance of two intervals of rapid field decay - about 700 years ago and the present one - suggests the opposite phenomenon. Perhaps a similar anomaly appeared regularly in South Africa, and is older than the data showed? If so, why is it repeated in the same place?
Over the past decade, researchers have accumulated seismic wave analysis data from earthquakes. Since seismic waves travel through the layers of the Earth, the speed at which they travel is an indication of the density of the layer. Scientists now know that a large area of slow seismic waves characterizes the main mantle boundary under southern Africa.
This particular region is most likely tens of millions of years old, and its boundaries are clear. It is interesting to note that the spot of reverse polarity practically coincides with its eastern edge.
Scientists believe that the unusual African mantle changes the flow of iron in the core from below, which, in turn, changes the behavior of the magnetic field at the edge of the seismic region and the reverse polarity patch.
It is assumed that this area grows rapidly and then slowly returns to normal. From time to time, a single spot of reversed polarity can grow large enough to dominate the southern hemisphere's magnetic field.
How does inversion happen?
The traditional idea of inversion is that it can start anywhere in the nucleus. However, the new conceptual model suggests that there may be specific locations at the core-mantle interface that contribute to these reversals of the magnetic field. It is not yet known whether the current magnetic field will begin to decrease in the next few thousand years, or if it will simply continue to weaken over the next two centuries.
But the evidence provided by the ancestors of modern South Africans will no doubt help scientists further study their proposed inversion mechanism. If this idea is correct, the pole reversal could start in Africa.
Magnetic storms are usually not considered a formidable natural phenomenon, such as earthquakes, tsunamis, typhoons. True, they disrupt radio communications in the high latitudes of the planet, make the compass needles dance. Now these hindrances are no longer terrible. Long-distance communications are increasingly conducted through satellites, with their help, navigators set the course for ships and aircraft.
It would seem that the vagaries of the magnetic field can no longer bother anyone. But just now, some facts have given rise to fears that changes in the Earth's magnetic field can cause catastrophes, before which the most formidable forces of nature will turn pale!
One such change in the field is happening today... Since the German mathematician and physicist Carl Gauss first gave a mathematical description of the magnetic field, subsequent measurements - for 150 years to the present day - show that the Earth's magnetic field has been steadily weakening.
In this regard, the questions seem natural: will the magnetic field disappear completely, and what could this threaten earthlings with?
Recall that our planet is continuously bombarded by cosmic particles, especially intensely by protons and electrons emitted by the Sun, the so-called solar wind. They rush past the Earth at an average speed of 400 km/s. The Earth's magnetosphere does not allow charged particles to reach the planet's surface. She directs them to the poles, where in the upper atmosphere they give rise to fantastic auroras. But if there is no magnetic field, if the flora and fauna are under such continuous shelling, then it can be assumed that radiation damage to organisms will have the most detrimental effect on the fate of the entire biosphere.
To judge how real such a threat is, one must remember how the Earth's magnetic field arises and whether there are any unreliable links in this mechanism that can fail.
According to modern concepts, the core of our planet consists of a solid part and a liquid shell. Heated by the solid core and cooled by the mantle located above, the liquid matter of the core is drawn into circulation, into convection, which breaks up into many separate circulating flows.
The same phenomenon is familiar to the terrestrial oceans, when sources of deep heat are close to the ocean floor, due to which it heats up. Then vertical currents appear in the water column. For example, such a current in the Pacific Ocean off the coast of Peru has been well studied. It brings a huge mass of nutrients from the depths to the surface of the waters, due to which this region of the ocean is especially rich in fish ...
The substance of the liquid part of the core is a melt with a high content of metals, and therefore it has good electrical conductivity. From the school course, we know that if a conductor moves in a magnetic field, crossing its lines, then an electromotive force is excited in it.
A weak interplanetary magnetic field could initially interact with the melt flows. The current generated by this, in turn, created a powerful magnetic field, which surrounded the core of the planet in rings.
In the bowels of the Earth, in principle, everything happens the same way as in a self-excited dynamo, the schematic model of which usually has every school physics classroom. The difference is that instead of wires, flows of liquid electrically conductive material act in the bowels. And, apparently, the analogy between the sections of the dynamo rotor and the convection flows of the melt in the bowels is quite legitimate. The mechanism that creates the Earth's magnetic field is therefore called the hydromagnetic dynamo.
But the picture, of course, is more complicated: the annular, otherwise they are called toroidal, fields do not go to the surface of the planet. Interacting with the same electrically conductive mobile liquid mass, they generate another, external field, with which we are dealing on the surface of the Earth.
Our planet with its external magnetic field is usually schematically depicted as a symmetrically magnetized ball with two poles. In reality, the external field is not so ideal in shape. The symmetry is broken by many magnetic anomalies.
Some of them are very significant and are called continental. One such anomaly is located in Eastern Siberia, the other is in South America. Such anomalies arise because the hydromagnetic dynamo in the bowels of the Earth is not “designed” as symmetrically as electrical machines built at a factory, where they ensure the alignment of the rotor and stator and carefully balance the rotors on special machines, achieving the coincidence of their centers of mass (more precisely, the main central axis of inertia) with the axis of rotation. Both the power of matter flows and the temperature conditions, on which the speed of their movement depends, are far from being the same in different zones of the earth's interior, where the natural dynamo operates. Most likely, a deep dynamo can be compared to a machine in which the sections in the rotor winding are of different thicknesses and the gap between the rotor and the stator changes.
Anomalies of a smaller scale - regional and local - are explained by the peculiarities of the composition of the earth's crust - such as, for example, the Kursk magnetic anomaly, which arose due to giant deposits of iron ore.
In a word, the mechanism that generates the Earth's magnetic field is stable, reliable, and it seems that there are no details in it that can suddenly fail. Moreover, according to G. Zoffel, a professor at the University of Munich, the electrical conductivity of the liquid material in the depths is so high that if, for any reason, the hydromagnetic dynamo suddenly “turns off”, the magnetic forces on the planet’s surface will signal this to us only after many millennia.
But one thing is the "breakdown" of the natural mechanism, another is the gradual attenuation of its action, similar to the cold snaps that gave rise to the glaciation of the planet.
To analyze this circumstance, we need a more detailed acquaintance with the behavior of the magnetic field: how and why it changes over time.
Any rock, any substance containing iron or other ferromagnetic element, is always under the influence of the Earth's magnetic field. Elementary magnets in this material tend to orient themselves like a compass needle along the field lines of force.
However, if the material is heated, then there will come a moment when the thermal motion of the particles becomes so energetic that it destroys the magnetic order. Then, when our material cools down, starting from a certain temperature (called the Curie point), the magnetic field will prevail over the forces of chaotic motion. The elementary magnets will line up again as the field tells them to, and will remain in this position if the body is not heated again. The field turns out to be "frozen" in the material.
This phenomenon makes it possible to confidently judge the past of the earth's magnetic field. Scientists manage to penetrate into such distances of times when the solid crust on the young planet cooled. Minerals preserved from that time tell about what the magnetic field was like two billion years ago.
When it comes to studies of periods that are much closer to us in time - within the last 10 thousand years - scientists prefer to take materials of artificial origin for analysis, rather than natural lavas or sediments. This is clay burnt by man - dishes, bricks, ritual figurines, etc., which appeared with the first steps of civilization. The advantage of artificial clay crafts is that archaeologists can date them fairly accurately.
At the Institute of Physics of the Earth, Russian Academy of Sciences, the laboratory of archeomagnetism was engaged in studying changes in the magnetic field. There were concentrated extensive data obtained in the laboratory and in leading foreign scientific centers. Russian scientists are also doing this.
Indeed, these data confirm that the magnetic field is weakening in our time. But a caveat is needed here: accurate measurements of the behavior of the field over long periods of time indicate that the planet's magnetic field is subject to numerous fluctuations with different periods. If we add them all up, we get the so-called “smoothed curve”, which coincides quite well with a sinusoid with a period of 8 thousand years.
At this time, the total value of the magnetic field is on the downward segment of the sinusoid. This is what caused the concern of some authors. Behind higher values, in front - further weakening of the field. It will continue for about another two thousand years. But then the strengthening of the field will begin. This phase will last for 4,000 years before the recession starts again. The previous maximum occurred at the beginning of our era. The multiplicity of oscillations of the magnetic field is apparently due to the lack of balance in the moving parts of the hydromagnetic dynamo, their different electrical conductivity.
It is important to note that the amplitude of the sinusoid is less than half the average field strength. In other words, these fluctuations cannot reduce the value of the field to zero in any way. This is the answer to those who believe that the current weakening of the field will eventually open the surface of the globe to the bombardment of particles from space.
As already mentioned, the curve is the sum of various fluctuations of the Earth's magnetic field overlapping each other - in total, about a dozen of them have been identified so far. Well-defined periods are 8000, 2700, 1800, 1200, 600 and 360 years long. The periods of 5400, 3600 and 900 years are less clearly traced.
Significant phenomena in the life of the planet are associated with some of these periods.
A period of 8000 years is undoubtedly of a global scale, in contrast to fluctuations, for example, of 600 or 360 years, which have a regional, local character.
Interrelations with many natural phenomena of the period of 1800 years are interesting. Geographer A. V. Shnitnikov compared various natural rhythms of the Earth and discovered their attachment to the astronomical phenomenon named. Great sares, when the Sun, Earth and Moon are on the same straight line and at the same time the Earth is located at the smallest distance from both the luminary and the satellite. In this case, the tidal forces reach their maximum value. The big sares is repeated after 1800 years (with deviations) and is accompanied by the expansion of the globe in the equatorial strip - due to the tidal wave, in which the World Ocean and the earth's crust participate. As a consequence of this, the moment of inertia of the planet changes, and it slows down its rotation. The position of the boundary of the polar ice cover is also changing, and the ocean level is rising. A large sares is reflected in the climate of the Earth - dry and wet periods begin to alternate in a different way. Such changes in nature in the past were reflected in the population of the planet: for example, the migration of peoples intensified ...
The Institute of Physics of the Earth set out to find out if there are any links between the phenomena caused by the Great Sares and the behavior of the magnetic field. It turned out that it is precisely the 1800-year period of field oscillations that is in good agreement with the rhythm of phenomena caused by the relative positions of the Sun, Earth and Moon. The beginnings and ends of the changes and their maxima coincide… This can be explained by the fact that in the liquid mass surrounding the core of the planet, during the Great Sares, the tidal wave also reached its maximum value, therefore, the interaction of matter flows with the internal field also changed.
In the last 10 thousand years, terrestrial nature has not suffered any disasters due to the restless magnetic field. But what hides a deeper past? As is known, the most dramatic events in the Earth's biosphere lie far beyond 10,000 years. Maybe they were caused by some changes in the magnetic field?
Here we will have to deal with a fact that has alarmed some scientists.
The magnetic fields of the past turned out to be "frozen" also in volcanic lavas, when they, cooling down, passed the Curie point. Magnetic fields are also imprinted in bottom sediments: particles sinking to the bottom, if they contain ferromagnets, like compass needles, are oriented along the lines of the magnetic field. It persists forever in petrified sediments, unless the sediments have been subjected to intense heat ...
Paleomagnetologists are studying ancient magnetic fields. They managed to detect truly grandiose changes that the magnetic field underwent in the distant past. The phenomenon of inversion was discovered - the change of magnetic poles. The north moved to the place of the south, the south to the place of the north.
By the way, the poles do not change so quickly - according to some estimates, the change lasts 5 or even 10 thousand years.
The last such movement occurred 700 thousand years ago. The previous one is another 96 thousand years earlier. There are hundreds of such shifts in the history of the planet. No regularity was found here - long quiet periods are known, they were replaced by times of frequent inversions.
The so-called "excursions" were also discovered - the departure of the magnetic poles from the geographic ones over long distances, ending, however, with a return to their former place.
Many have tried to explain the polarity reversals. American scientists R. Muller and D. Morris, for example, consider the impact of giant meteorites to be the root cause of this. The "shaking" of the planet forced to change the nature of the movement of melts in its depths. The authors of this hypothesis were based on the fact that 65 million years ago there was an inversion and a fall to the Earth of a large cosmic body, as evidenced by the deposits of that time, rich in cosmic iridium. The hypothesis looked spectacular, but was unconvincing, if only because the temporal connection between these events has been proven very poorly. According to another hypothesis, inversions are caused by deep melt flows when giant clods of ferromagnetic material get into them. These clods, concentrating in themselves the lines of the magnetic field, seem to “pull” it along with them.
And this hypothesis is objectionable.
Obviously, over the billions of years of its existence, the core of the Earth must have increased in size. It would seem that this could not but affect the Earth's magnetic field. Meanwhile, scientists who have information about what the planet's magnetic field was like two billion years ago, compare these data with today's data and do not even find traces of the influence of core growth on the magnetic field. Can the state of the field be affected by a phenomenon of a much more modest scale, such as the hypothetical "clods"?
The currently accepted theory of the hydromagnetic dynamo is capable of explaining the reversal, but this theory does not say that the change of poles is obligatory, it only does not contradict this phenomenon.
The inversions are caused by the same "constructive imperfections" of the natural hydromagnetic dynamo. But these are other defects than those that cause the already familiar spectrum of ten oscillations of the magnetic field, oscillations that repeat uniformly through certain periods of time. Inversions do not have such a regular systematic character.
It could be assumed that the phenomenon of inversion, the search for its causes and its consequences will arouse the interest of only researchers of terrestrial magnetism. But no, this phenomenon has attracted the attention of a wide range of scientists, including those who study the development of the earth's biosphere.
Recently, several scientific papers have suggested that the Earth's magnetic field disappears during reversals. Thus, we are talking about the fact that the planet loses its invisible armor for some time. And this, apparently, can lead to the death of many species of plants and animals. That is why some people see the danger in the changes that the magnetic field is subject to as more formidable than that carried by the destructive trio: earthquakes, tsunamis, typhoons.
The authors of this assumption, in order to prove their correctness, cite the relationship between the extinction of dinosaurs that disappeared from the face of the Earth 65 million years ago and the frequent inversions characteristic of that period.
The hypothesis of such a radical influence of polarity reversals on the development of the entire living nature of the Earth was met with particular satisfaction by evolutionists, who in the recent past modeled with the help of a computer the history of the biosphere of our planet, starting from the primary forms of living matter. The program included all the factors known by that time that affect mutations and natural selection. The results of the study were unexpected: the evolution from the first cell to man in the mathematical interpretation was much slower than in the real conditions of terrestrial nature.
Obviously, the scientists concluded, the program did not take into account some energetic factors that force nature to change species at once. Now, they believe, one of such strong accelerators of evolution has been found - this is the impact on the organic world of cosmic radiation during those periods when the poles exchanged places ... Something similar, at least, to the Chernobyl disaster.
Either alarming or encouraging against this background sounds the assertion of American geophysicists that they discovered lava layers in the state of Oregon, which show that the field "frozen" in them turned 90 degrees in just two weeks. In other words, change does not necessarily take millennia, but can be almost instantaneous. That is, the time of the destructive effects of cosmic radiation is small, which reduces their danger. It is not clear why the field turned not by 180 degrees, but only by 90.
However, the assumption that the magnetic field disappears during polarity reversals is just an assumption, and not a truth based on reliable facts. On the contrary, some paleomagnetic studies suggest that the field is conserved during reversals. True, it has a non-dipole structure and is much weaker - by a factor of 10, and even 20 times. Serious objections were raised by the interpretation of the sharp field changes found in lavas from the state of Oregon. Professor G. Zoffel, mentioned by us, believes that the discovery of American colleagues can be explained in a completely different way, for example, as follows: a magnetic field, born at that moment, was “frozen” into the cooling lava.
But these objections do not exclude the possibility of a direct, perhaps weakened, effect of cosmic particles on the plant and animal world. Many scientists have joined in the search for answers to the questions posed by this hypothesis.
Noteworthy are the considerations expressed at the time by V. P. Shcherbakov, an employee of the Institute of Physics of the Earth of the USSR Academy of Sciences. He believed that during reversals, the planet's magnetic field, albeit weakened, retains its structure, in particular, the magnetic field lines in the region of the poles still rest against the surface of the planet. Above the moving poles during periods of inversion in the magnetosphere, there are constantly, as in our days, funnels into which cosmic particles seem to fall.
During periods of inversions, with a weakened field, they can fly up to the surface of the green ball at the closest distances, and possibly even reach it.
Paleontologists also joined in the search. For example, the German professor G. Herm, who, in collaboration with many foreign laboratories, studied bottom sediments dated to the end of the Cretaceous. He found evidence that there was a jump in the development of species during these times. However, this scientist considers the then inversions to be just one of the factors that pushed evolution. Mr. Herm does not find any grounds for worrying about the future life on the planet in the event that abrupt changes occur in the magnetic field.
Professor of Moscow State University B. M. Mednikov, an evolutionary biologist, also does not consider them dangerous and explains why. The main protection against the solar wind, he says, is still not the magnetic field, but the atmosphere. Protons and electrons lose their energy in its upper layers above the poles of the planet, causing the air molecules to glow, “shine”. If suddenly there is no magnetic field, then the aurora will probably not only be over the poles, where the magnetosphere is now driving particles, but all over the sky - but at the same high altitudes. The solar wind will still remain safe for the living.
B. M. Mednikov also says that evolution does not need to be “spurred on” by cosmic forces. The latest, more advanced computer models of evolution convince us that its real speed is fully explained by molecular causes internal to the organism. When, at the birth of a new organism, its apparatus of heredity is created, in one out of a hundred thousand cases, the copying of parental traits occurs with an error. This is quite enough for animal and plant species to keep up with changes in the environment. Do not forget about the mechanism of mass distribution of gene mutations through viruses.
According to magnetologists, the objections of B. M. Mednikov cannot cross out the problem. If the direct impact of changes in the magnetic field on the biosphere is unlikely, then there is also an indirect one. There are, for example, undoubted relationships between the magnetic field of the planet and its climate ...
As you can see, there are many serious contradictions in the problem of the relationship between the magnetic field and the biosphere. Contradictions, as always, encourage researchers to search.
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Are the most powerful thunderstorms inside the earth?The most unpredictable processes
Among the various scenarios of the "end of the world" often appears such as a change in the direction of the lines of force of the Earth's magnetic field. Simply put, when the north magnetic pole is in the southern hemisphere, and vice versa. Let us consider why this is possible, and what dangers for us may result from this.
Why do we need the earth's magnetic field
The Earth's magnetic field is a unique phenomenon. No terrestrial planet has anything close. Even the magnetic fields of Saturn, Uranus and Neptune are weaker. Only at Jupiter it is more powerful, but that's why he is a giant. Until now, science does not know where the Earth's magnetic field comes from, or why it is so strong. It is assumed that this is somehow connected with the Moon - after all, no other planet, except for the Earth, has such a relatively large satellite, whose mass is only 80 times less than the mass of the planet. But how the Moon generates such a magnetic field near the Earth is still not really clear.
One thing we know for sure. Without the magnetic field, there would be no life on Earth. Streams of charged cosmic particles falling into the vicinity of the Earth from outer space are captured by the force lines of the magnetic field of our planet - its magnetosphere - and do not reach its surface. They remain at an altitude of 500 to 70,000 km above the Earth, forming radiation belts in which astronauts cannot stay for a long time.
If the Earth's magnetic field (geomagnetic field) suddenly disappeared forever, then after some time, hard cosmic radiation would lead to the disappearance of all higher life on its surface. Life would remain only in water at a depth of more than ten meters and in deep caves on land.
Geomagnetic field reversals
From childhood, we are used to the fact that the compass needle should point to the north. True, there are magnetic storms and anomalies in which the compass, as they say, goes crazy, but then everything falls into place again. However, the compass was invented only a few centuries ago, and the Earth has been around for billions of years. And it turned out that the current position of the Earth's magnetic poles is not the only possible one. There were long periods in the history of our planet when the compass needle, once we were there, would point south!
This was discovered by the phenomenon of remanence of sedimentary rocks in different places on the Earth, especially at the bottom of the oceans. Having determined the time of formation of these rocks using various methods, scientists have compiled a scale of changes in the polarity of the geomagnetic field.
It turned out that the magnetic poles occupied their current position on the cardinal points approximately 780 thousand years ago. This last period is called the Brunhes era. And before that, about one million and 800 thousand years, the era of the reverse magnetization of Matuyama continued. However, it was not uniform. Inside it, there are at least five episodes of shorter duration - from several thousand to 220 thousand years - when the direction of the magnetic needle would coincide with the modern one.
Strictly speaking, this current epoch should be considered the epoch of reversed magnetization. After all, the lines of force of the geomagnetic field now come out of the pole located in the Southern Hemisphere, therefore this particular pole is the North magnetic, and located in the Northern Hemisphere is the South magnetic. But in this case, physics gave way to familiar geography, so as not to create confusion among people.
Why is this happening
The reasons for the change in the direction of the geomagnetic field lines remain completely unknown. Science does not yet know whether this change can be predicted by some other geophysical parameters. For example, by changing the strength of the geomagnetic field or by the movement of the poles. After all, the position of the magnetic poles on the earth's surface does not remain unchanged. They are moving. Moreover, according to measurements, in recent decades they are moving faster and faster.
So, if the North (let's call it out of habit) magnetic pole in the 1970s drifted at a speed of 10 km per year, then at the beginning of the 21st century it was already 50-60 km per year. In the early years of this century, he left the islands of the Canadian Arctic and is heading towards Russia. This year it will cross the 180th meridian and will be closer to Eurasia than to North America.
The intensity of the geomagnetic field of the Earth, judging by the same residual magnetization - in this case, ceramic products - has been steadily weakening over the past few centuries. Could this be a sign of an upcoming polarity reversal? In other words, we do not yet know what exactly can portend a change in the Earth's magnetic poles, what kind of omens this phenomenon has.
Danger for technologically advanced humanity
If the geomagnetic field is excited, as one hypothesis claims, by flows of matter in the mantle - the same ones that are responsible for the movement of tectonic plates and mountain building processes - then the change of magnetic poles can be accompanied by catastrophic earthquakes and volcanic eruptions. But the main danger is, as already mentioned, the temporary disappearance of the geomagnetic field during polarity reversal. According to existing theoretical models, the Earth's magnetic poles will disappear before they switch places. And no one knows how long.
However, there are reasons for optimism. After all, reversals of the geomagnetic field have happened on Earth many times, including several dozen times over the past five million years. No major extinctions of living beings occurred during these periods. Therefore, there is reason to believe that such episodes were very short-lived. True, there is another explanation: of the animals, including human ancestors, only those who were accustomed to finding refuge in caves survived in these episodes. That is why the remains of primitive people are found mainly there.
The inversion of the geomagnetic field, no matter how short-term it may be, threatens with dangers for modern mankind due to its fatal dependence on high technologies. The magnetic polarity reversal, which will also affect the state of the earth's ionosphere, will inevitably lead to serious failures of all satellite communication systems, to the impossibility of long-range radio communications and navigation for aircraft and ships. Our civilization then in the blink of an eye can slide down to the technical level of the Middle Ages, which threatens with unpredictable social consequences.
Simply put, the main danger for humanity, in the event of a change in the magnetic poles, is, as in other natural disasters, the person himself, the spontaneous and unpredictable behavior of his masses, seized by mass panic and becoming the subject of manipulation.
And our very ignorance of when and how this can happen shows how little modern science, which has looked deep into the Universe tens of billions of light years, knows so far about what is happening at a depth of only six thousand kilometers under our feet.
The Earth's magnetic field is similar to the magnetic field of a giant permanent magnet tilted at an angle of 11 degrees to its axis of rotation. But there is a nuance here, the essence of which is that the Curie temperature for iron is only 770°C, while the temperature of the Earth's iron core is much higher, and only on its surface is about 6000°C. At this temperature, our magnet would not be able to maintain its magnetization. This means that since the core of our planet is not magnetic, terrestrial magnetism has a different nature. So where does the Earth's magnetic field come from?
As you know, magnetic fields surround electric currents, so there is every reason to assume that currents circulating in a molten metal core are the source of the earth's magnetic field. The shape of the Earth's magnetic field is indeed similar to the magnetic field of a coil with current.
The magnitude of the magnetic field measured on the surface of the Earth is about half a Gauss, while the lines of force, as it were, leave the planet from the side of the south pole and enter its north pole. At the same time, over the entire surface of the planet, the magnetic induction varies from 0.3 to 0.6 Gauss.
In practice, the presence of a magnetic field near the Earth is explained by the dynamo effect arising from the current circulating in its core, but this magnetic field is not always constant in direction. Rock samples taken in the same places, but having different ages, differ in the direction of magnetization. Geologists report that over the past 71 million years, the Earth's magnetic field has reversed 171 times!
Although the dynamo effect has not been studied in detail, the rotation of the Earth certainly plays an important role in the generation of currents, which are supposed to be the source of the Earth's magnetic field.
The Mariner 2 probe, which explored Venus, found that Venus does not have such a magnetic field, although its core, like the Earth's core, contains enough iron.
The answer is that the period of rotation of Venus around its axis is 243 days on Earth, that is, the dynamo generator of Venus rotates 243 times slower, and this is not enough to produce a real dynamo effect.
Interacting with particles of the solar wind, the Earth's magnetic field creates the conditions for the emergence near the poles of the so-called auroras.
The north side of the compass needle is the magnetic north pole, which always points towards the geographic north pole, which is practically the magnetic south pole. After all, as you know, opposite magnetic poles attract each other.
However, the simple question is, "how does the Earth get its magnetic field?" - still does not have a clear answer. It is clear that the generation of the magnetic field is associated with the rotation of the planet around its axis, because Venus with a similar composition of the core, but rotating 243 times slower, does not have a measurable magnetic field.
It seems plausible that from the rotation of the liquid of the metallic core, which constitutes the main part of this core, a picture of a rotating conductor arises, creating a dynamo effect and working like an electric generator.
Convection in the liquid of the outer part of the core leads to its circulation with respect to the Earth. This means that the electrically conductive material moves relative to the magnetic field. If it turns out to be charged due to friction between the layers in the core, then the effect of a coil with current is quite possible. Such a current is quite able to maintain the Earth's magnetic field. Large-scale computer models confirm the reality of this theory.
In the 1950s, as part of the Cold War strategy, US Navy ships towed sensitive magnetometers across the ocean floor while they looked for a way to detect Soviet submarines. In the course of observations, it turned out that the Earth's magnetic field fluctuates within 10% with respect to the magnetism of the rocks of the seabed itself, which had the opposite direction of magnetization. The result was a pattern of reversals that occurred up to 4 million years ago, this was calculated by the potassium-argon archaeological method.
Andrey Povny