How the earth's magnetic field is formed briefly. The real source of the earth's magnetic field has been identified. Radiation belts and cosmic rays
In 1905, Einstein named the cause of terrestrial magnetism one of the five main mysteries of contemporary physics.
Also in 1905, the French geophysicist Bernard Brunhes carried out measurements of the magnetism of Pleistocene lava deposits in the southern department of Cantal. The magnetization vector of these rocks was almost 180 degrees with the vector of the planetary magnetic field (his compatriot P. David obtained similar results even a year earlier). Brunhes came to the conclusion that three quarters of a million years ago, during the outpouring of lava, the direction of the geomagnetic field lines was opposite to the modern one. This is how the effect of inversion (reversal of polarity) of the Earth's magnetic field was discovered. In the second half of the 1920s, Brunhes's conclusions were confirmed by P. L. Mercanton and Monotori Matuyama, but these ideas received recognition only by the middle of the century.
We now know that the geomagnetic field has existed for at least 3.5 billion years, and during this time the magnetic poles have swapped places thousands of times (Brunhes and Matuyama studied the most recent reversal, which now bears their names). Sometimes the geomagnetic field maintains its orientation for tens of millions of years, and sometimes for no more than five hundred centuries. The inversion process itself usually takes several thousand years, and upon completion, the field strength, as a rule, does not return to its previous value, but changes by several percent.
The mechanism of geomagnetic inversion is not entirely clear to this day, and even a hundred years ago it did not allow for a reasonable explanation at all. Therefore, the discoveries of Brunhes and David only reinforced Einstein’s assessment - indeed, terrestrial magnetism was extremely mysterious and incomprehensible. But by that time it had been studied for over three hundred years, and in the 19th century it was studied by such stars of European science as the great traveler Alexander von Humboldt, the brilliant mathematician Carl Friedrich Gauss and the brilliant experimental physicist Wilhelm Weber. So Einstein truly looked at the root.
How many magnetic poles do you think our planet has? Almost everyone will say that two are in the Arctic and Antarctic. In fact, the answer depends on the definition of the concept of pole. Geographic poles are considered to be the points of intersection of the earth's axis with the surface of the planet. Since the Earth rotates as a rigid body, there are only two such points and nothing else can be thought of. But with magnetic poles the situation is much more complicated. For example, a pole can be considered a small area (ideally, again a point) where the magnetic lines of force are perpendicular to the earth's surface. However, any magnetometer records not only the planetary magnetic field, but also the fields of local rocks, ionospheric electric currents, solar wind particles and other additional sources of magnetism (and their average share is not so small, on the order of several percent). The more accurate the device, the better it does this - and therefore makes it increasingly difficult to isolate the true geomagnetic field (it is called the main one), the source of which is located in the depths of the earth. Therefore, pole coordinates determined by direct measurement are not stable even over a short period of time.
You can act differently and establish the position of the pole on the basis of certain models of terrestrial magnetism. To a first approximation, our planet can be considered a geocentric magnetic dipole, the axis of which passes through its center. Currently, the angle between it and the earth's axis is 10 degrees (several decades ago it was more than 11 degrees). With more accurate modeling, it turns out that the dipole axis is shifted relative to the center of the Earth towards the northwestern part of the Pacific Ocean by about 540 km (this is an eccentric dipole). There are other definitions.
But that is not all. The Earth's magnetic field actually does not have dipole symmetry and therefore has multiple poles, and in huge numbers. If we consider the Earth to be a magnetic quadrupole, a quadrupole, we will have to introduce two more poles - in Malaysia and in the southern part of the Atlantic Ocean. The octupole model specifies the eight poles, etc. The modern most advanced models of terrestrial magnetism operate with as many as 168 poles. It is worth noting that during the inversion, only the dipole component of the geomagnetic field temporarily disappears, while the others change much less.
Poles in reverse
Many people know that the generally accepted names of the poles are exactly the opposite. In the Arctic there is a pole to which the northern end of the magnetic needle points - therefore, it should be considered southern (like poles repel, opposite poles attract!). Likewise, the magnetic north pole is based at high latitudes in the Southern Hemisphere. However, traditionally we name the poles according to geography. Physicists have long agreed that lines of force come out of the north pole of any magnet and enter the south. It follows that the lines of earth's magnetism leave the south geomagnetic pole and are drawn towards the north. This is the convention, and you shouldn’t violate it (it’s time to remember Panikovsky’s sad experience!).
The magnetic pole, no matter how you define it, does not stand still. The North Pole of the geocentric dipole had coordinates of 79.5 N and 71.6 W in 2000, and 80.0 N and 72.0 W in 2010. The true North Pole (the one revealed by physical measurements) has shifted since 2000 from 81.0 N and 109.7 W to 85.2 N and 127.1 W. For almost the entire twentieth century it did no more than 10 km per year, but after 1980 it suddenly began to move much faster. In the early 1990s, its speed exceeded 15 km per year and continues to grow.
As Lawrence Newitt, the former head of the geomagnetic laboratory of the Canadian Geological Research Service, told Popular Mechanics, the true pole is now migrating to the northwest, moving 50 km annually. If the vector of its movement does not change for several decades, then by the middle of the 21st century it will end up in Siberia. According to a reconstruction carried out several years ago by the same Newitt, in the 17th and 18th centuries the north magnetic pole mainly shifted to the southeast and only turned to the northwest around 1860. The true south magnetic pole has been moving in the same direction for the last 300 years, and its average annual displacement does not exceed 10–15 km.
Where does the Earth's magnetic field even come from? One possible explanation is simply glaring. The Earth has an inner solid iron-nickel core, the radius of which is 1220 km. Since these metals are ferromagnetic, why not assume that the inner core has static magnetization, which ensures the existence of the geomagnetic field? The multipolarity of terrestrial magnetism can be attributed to the asymmetry of the distribution of magnetic domains inside the core. Polar migration and geomagnetic field reversals are more difficult to explain, but we can probably try.
However, nothing comes of this. All ferromagnets remain ferromagnetic (that is, they retain spontaneous magnetization) only below a certain temperature - the Curie point. For iron it is 768°C (for nickel it is much lower), and the temperature of the Earth's inner core significantly exceeds 5000 degrees. Therefore, we have to part with the hypothesis of static geomagnetism. However, it is possible that there are cooled planets with ferromagnetic cores in space.
Let's consider another possibility. Our planet also has a liquid outer core approximately 2,300 km thick. It consists of a melt of iron and nickel with an admixture of lighter elements (sulfur, carbon, oxygen and, possibly, radioactive potassium - no one knows for sure). The temperature of the lower part of the outer core almost coincides with the temperature of the inner core, and in the upper zone at the boundary with the mantle it drops to 4400°C. Therefore, it is quite natural to assume that due to the rotation of the Earth, circular currents are formed there, which may be the cause of the emergence of terrestrial magnetism.
Convective dynamo
“To explain the appearance of the poloidal field, it is necessary to take into account the vertical flows of nuclear matter. They are formed due to convection: heated iron-nickel melt floats up from the lower part of the core towards the mantle. These jets are twisted by the Coriolis force like the air currents of cyclones. In the Northern Hemisphere, updrafts rotate clockwise, while in the Southern Hemisphere they rotate counterclockwise, explains University of California professor Gary Glatzmeier. - When approaching the mantle, the core material cools down and begins to move back inward. The magnetic fields of the ascending and descending flows cancel each other, and therefore the field is not established vertically. But in the upper part of the convection jet, where it forms a loop and moves horizontally for a short time, the situation is different. In the Northern Hemisphere, the field lines, which faced west before convective ascent, rotate clockwise by 90 degrees and are oriented north. In the Southern Hemisphere, they turn counterclockwise from the east and also head north. As a result, a magnetic field is generated in both hemispheres, pointing from south to north. Although this is by no means the only possible explanation for the emergence of the poloidal field, it is considered the most likely.”
This is precisely the scheme that geophysicists discussed 80 years ago. They believed that the flows of the conducting fluid of the outer core, due to their kinetic energy, generate electric currents covering the earth's axis. These currents generate a magnetic field of predominantly dipole type, the field lines of which on the Earth's surface are elongated along the meridians (such a field is called poloidal). This mechanism evokes an association with the operation of a dynamo, hence its name.
The described scheme is beautiful and visual, but, unfortunately, wrong. It is based on the assumption that the movement of matter in the outer core is symmetrical relative to the earth's axis. However, in 1933, the English mathematician Thomas Cowling proved the theorem according to which no axisymmetric flows are capable of ensuring the existence of a long-term geomagnetic field. Even if it appears, its age will be short-lived, tens of thousands of times less than the age of our planet. We need a more complex model.
“We don’t know exactly when Earth’s magnetism arose, but it could have happened soon after the formation of the mantle and outer core,” says David Stevenson, one of the leading experts on planetary magnetism, a professor at the California Institute of Technology. - To turn on the geodynamo, an external seed field is required, and not necessarily a powerful one. This role, for example, could be taken on by the magnetic field of the Sun or the fields of currents generated in the core due to the thermoelectric effect. Ultimately, this is not too important; there were enough sources of magnetism. In the presence of such a field and the circular motion of flows of conducting fluid, the launch of an intraplanetary dynamo became simply inevitable.”
Magnetic protection
Earth's magnetism is monitored using an extensive network of geomagnetic observatories, the creation of which began in the 1830s.
For the same purposes, shipborne, aviation and space instruments are used (for example, scalar and vector magnetometers of the Danish Ørsted satellite, operating since 1999).
Geomagnetic field strengths range from approximately 20,000 nanoteslas off the coast of Brazil to 65,000 nanoteslas near the south magnetic pole. Since 1800, its dipole component has decreased by almost 13% (and since the mid-16th century by 20%), while its quadrupole component has increased slightly. Paleomagnetic studies show that for several thousand years before the beginning of our era, the intensity of the geomagnetic field persistently climbed up, and then began to decrease. Nevertheless, the current planetary dipole moment is significantly higher than its average value over the past hundred and fifty million years (in 2010, the results of paleomagnetic measurements were published indicating that 3.5 billion years ago the Earth’s magnetic field was half as strong as it is today). This means that the entire history of human societies from the emergence of the first states to our time fell on a local maximum of the earth’s magnetic field. It is interesting to think about whether this has affected the progress of civilization. This assumption ceases to seem fantastic if we consider that the magnetic field protects the biosphere from cosmic radiation.
And here is one more circumstance that is worth noting. In our planet’s youth and even adolescence, all the matter in its core was in the liquid phase. The solid inner core formed relatively recently, perhaps only a billion years ago. When this happened, the convection currents became more orderly, which led to more stable operation of the geodynamo. Because of this, the geomagnetic field has gained in magnitude and stability. It can be assumed that this circumstance had a beneficial effect on the evolution of living organisms. In particular, the strengthening of geomagnetism improved the protection of the biosphere from cosmic radiation and thereby facilitated the exit of life from the ocean to land.
Here is the generally accepted explanation for such a launch. For simplicity, let the seed field be almost parallel to the Earth's rotation axis (in fact, it is sufficient if it has a non-zero component in this direction, which is almost inevitable). The speed of rotation of the material of the outer core decreases as the depth decreases, and due to its high electrical conductivity, the magnetic field lines move with it - as physicists say, the field is “frozen” into the medium. Therefore, the force lines of the seed field will bend, going forward at greater depths and falling behind at shallower ones. Eventually they will stretch and deform so much that they will give rise to a toroidal field, circular magnetic loops that span the Earth's axis and point in opposite directions in the northern and southern hemispheres. This mechanism is called the w-effect.
According to Professor Stevenson, it is very important to understand that the toroidal field of the outer core arose due to the poloidal seed field and, in turn, gave rise to a new poloidal field observed at the earth's surface: “Both types of planetary geodynamo fields are interconnected and cannot exist without each other.” .
15 years ago, Gary Glatzmeier, together with Paul Roberts, published a very beautiful computer model of the geomagnetic field: “In principle, to explain geomagnetism, there has long been an adequate mathematical apparatus - the equations of magnetic hydrodynamics plus equations describing the force of gravity and heat flows inside the earth's core. Models based on these equations are very complex in their original form, but they can be simplified and adapted for computer calculations. That's exactly what Roberts and I did. A run on a supercomputer made it possible to construct a self-consistent description of the long-term evolution of the speed, temperature and pressure of matter flows in the outer core and the associated evolution of magnetic fields. We also found out that if we play the simulation over time intervals of the order of tens and hundreds of thousands of years, then geomagnetic field inversions inevitably occur. So in this respect, our model does a good job of conveying the planet's magnetic history. However, there is a difficulty that has not yet been resolved. The parameters of the material of the outer core, which are included in such models, are still too far from real conditions. For example, we had to accept that its viscosity is very high, otherwise the resources of the most powerful supercomputers would not be enough. In fact, this is not the case; there is every reason to believe that it almost coincides with the viscosity of water. Our current models are powerless to take into account turbulence, which undoubtedly occurs. But computers are gaining strength every year, and in ten years there will be much more realistic simulations.”
“The operation of a geodynamo is inevitably associated with chaotic changes in the flow of iron-nickel melt, which result in fluctuations in magnetic fields,” adds Professor Stevenson. - Inversions of terrestrial magnetism are simply the strongest possible fluctuations. Since they are stochastic in nature, they can hardly be predicted in advance - at least we don’t know how to do so.”
Let's understand together what a magnetic field is. After all, many people live in this field all their lives and don’t even think about it. It's time to fix it!
A magnetic field
A magnetic field- a special type of matter. It manifests itself in the action on moving electric charges and bodies that have their own magnetic moment (permanent magnets).
Important: the magnetic field does not affect stationary charges! A magnetic field is also created by moving electric charges, or by a time-varying electric field, or by the magnetic moments of electrons in atoms. That is, any wire through which current flows also becomes a magnet!
A body that has its own magnetic field.
A magnet has poles called north and south. The designations "north" and "south" are given for convenience only (like "plus" and "minus" in electricity).
The magnetic field is represented by magnetic power lines. The lines of force are continuous and closed, and their direction always coincides with the direction of action of the field forces. If metal shavings are scattered around a permanent magnet, the metal particles will show a clear picture of the magnetic field lines coming out of the north pole and entering the south pole. Graphic characteristic of a magnetic field - lines of force.
Characteristics of the magnetic field
The main characteristics of the magnetic field are magnetic induction, magnetic flux And magnetic permeability. But let's talk about everything in order.
Let us immediately note that all units of measurement are given in the system SI.
Magnetic induction B – vector physical quantity, which is the main force characteristic of the magnetic field. Denoted by the letter B . Unit of measurement of magnetic induction – Tesla (T).
Magnetic induction shows how strong the field is by determining the force it exerts on a charge. This force is called Lorentz force.
Here q - charge, v - its speed in a magnetic field, B - induction, F - Lorentz force with which the field acts on the charge.
F– a physical quantity equal to the product of magnetic induction by the area of the circuit and the cosine between the induction vector and the normal to the plane of the circuit through which the flux passes. Magnetic flux is a scalar characteristic of a magnetic field.
We can say that magnetic flux characterizes the number of magnetic induction lines penetrating a unit area. Magnetic flux is measured in Weberach (Wb).
Magnetic permeability– coefficient that determines the magnetic properties of the medium. One of the parameters on which the magnetic induction of a field depends is magnetic permeability.
Our planet has been a huge magnet for several billion years. The induction of the Earth's magnetic field varies depending on the coordinates. At the equator it is approximately 3.1 times 10 to the minus fifth power of Tesla. In addition, there are magnetic anomalies where the value and direction of the field differ significantly from neighboring areas. Some of the largest magnetic anomalies on the planet - Kursk And Brazilian magnetic anomalies.
The origin of the Earth's magnetic field still remains a mystery to scientists. It is assumed that the source of the field is the liquid metal core of the Earth. The core is moving, which means the molten iron-nickel alloy is moving, and the movement of charged particles is the electric current that generates the magnetic field. The problem is that this theory ( geodynamo) does not explain how the field is kept stable.
The Earth is a huge magnetic dipole. The magnetic poles do not coincide with the geographic ones, although they are in close proximity. Moreover, the Earth's magnetic poles move. Their displacement has been recorded since 1885. For example, over the past hundred years, the magnetic pole in the Southern Hemisphere has shifted almost 900 kilometers and is now located in the Southern Ocean. The pole of the Arctic hemisphere is moving through the Arctic Ocean to the East Siberian magnetic anomaly; its movement speed (according to 2004 data) was about 60 kilometers per year. Now there is an acceleration of the movement of the poles - on average, the speed is growing by 3 kilometers per year.
What is the significance of the Earth's magnetic field for us? First of all, the Earth's magnetic field protects the planet from cosmic rays and solar wind. Charged particles from deep space do not fall directly to the ground, but are deflected by a giant magnet and move along its lines of force. Thus, all living things are protected from harmful radiation.
Several events have occurred over the course of Earth's history. inversions(changes) of magnetic poles. Pole inversion- this is when they change places. The last time this phenomenon occurred was about 800 thousand years ago, and in total there were more than 400 geomagnetic inversions in the history of the Earth. Some scientists believe that, given the observed acceleration of the movement of the magnetic poles, the next pole inversion should be expected in the next couple of thousand years.
Fortunately, a pole change is not yet expected in our century. This means that you can think about pleasant things and enjoy life in the good old constant field of the Earth, having considered the basic properties and characteristics of the magnetic field. And so that you can do this, there are our authors, to whom you can confidently entrust some of the educational troubles with confidence! Coursework on international and national law and other types of work you can order using the link.
In recent days, a large amount of news about the Earth's magnetic field has appeared on scientific information sites. For example, news that it has been changing significantly recently, or that the magnetic field contributes to the leakage of oxygen from the earth’s atmosphere, or even that cows in pastures are oriented along the lines of the magnetic field. What is a magnetic field and how important is all this news?
The Earth's magnetic field is the area around our planet where magnetic forces operate. The question of the origin of the magnetic field has not yet been completely resolved. However, most researchers agree that the presence of the Earth's magnetic field is at least partly due to its core. The earth's core consists of a solid interior and a liquid exterior. The rotation of the Earth creates constant currents in the liquid core. As the reader may remember from physics lessons, the movement of electric charges results in the appearance of a magnetic field around them.
One of the most common theories explaining the nature of the field, the theory of the dynamo effect, assumes that convective or turbulent movements of a conducting fluid in the core contribute to self-excitation and maintenance of the field in a stationary state.
The earth can be considered as a magnetic dipole. Its south pole is located at the geographic North Pole, and its north pole, respectively, is at the South Pole. In fact, the geographic and magnetic poles of the Earth do not coincide not only in “direction”. The magnetic field axis is tilted relative to the Earth's rotation axis by 11.6 degrees. Since the difference is not very significant, we can use a compass. Its arrow points precisely to the Earth's South Magnetic Pole and almost exactly to the North Geographic Pole. If the compass had been invented 720 thousand years ago, it would have pointed to both the geographic and magnetic north poles. But more on that below.
The magnetic field protects the inhabitants of the Earth and artificial satellites from the harmful effects of cosmic particles. Such particles include, for example, ionized (charged) solar wind particles. The magnetic field changes the trajectory of their movement, directing the particles along the field lines. The necessity of a magnetic field for the existence of life narrows the range of potentially habitable planets (if we proceed from the assumption that hypothetically possible life forms are similar to earthly inhabitants).
Scientists do not rule out that some terrestrial planets do not have a metallic core and, accordingly, lack a magnetic field. Until now, planets made of solid rock, like Earth, were thought to contain three main layers: a solid crust, a viscous mantle, and a solid or molten iron core. In a recent paper, scientists from the Massachusetts Institute of Technology proposed the formation of "rocky" planets without a core. If the theoretical calculations of the researchers are confirmed by observations, then to calculate the probability of meeting humanoids in the Universe, or at least something resembling illustrations from a biology textbook, it will be necessary to rewrite them.
Earthlings may also lose their magnetic protection. True, geophysicists cannot yet say exactly when this will happen. The fact is that the Earth's magnetic poles are not constant. Periodically they change places. Not long ago, researchers found that the Earth “remembers” the reversal of the poles. Analysis of such “memories” showed that over the past 160 million years, magnetic north and south have changed places about 100 times. The last time this event occurred was about 720 thousand years ago.
The change of poles is accompanied by a change in the configuration of the magnetic field. During the “transition period,” significantly more cosmic particles that are dangerous to living organisms penetrate to Earth. One of the hypotheses explaining the disappearance of dinosaurs states that the giant reptiles became extinct precisely during the next pole change.
In addition to the “traces” of planned activities to change the poles, researchers noticed dangerous shifts in the Earth’s magnetic field. An analysis of data on his condition over several years showed that in recent months, things began to happen to him. Scientists have not recorded such sharp “movements” of the field for a very long time. The area of concern to researchers is located in the South Atlantic Ocean. The "thickness" of the magnetic field in this area does not exceed a third of the "normal" one. Researchers have long noticed this “hole” in the Earth’s magnetic field. Data collected over 150 years show that the field here has weakened by ten percent over this period.
At the moment, it is difficult to say what threat this poses to humanity. One of the consequences of weakening the field strength may be an increase (albeit insignificant) in the oxygen content in the earth's atmosphere. The connection between the Earth's magnetic field and this gas was established using the Cluster satellite system, a project of the European Space Agency. Scientists have found that the magnetic field accelerates oxygen ions and “throws” them into outer space.
Despite the fact that the magnetic field cannot be seen, the inhabitants of the Earth feel it well. Migratory birds, for example, find their way, focusing on it. There are several hypotheses explaining how exactly they sense the field. One of the latest suggests that birds perceive a magnetic field. Special proteins - cryptochromes - in the eyes of migratory birds are able to change their position under the influence of a magnetic field. The authors of the theory believe that cryptochromes can act as a compass.
In addition to birds, sea turtles use the Earth's magnetic field instead of GPS. And, as an analysis of satellite photographs presented as part of the Google Earth project showed, cows. After studying photographs of 8,510 cows in 308 areas of the world, scientists concluded that these animals preferentially (or from south to north). Moreover, the “reference points” for cows are not geographical, but rather the magnetic poles of the Earth. The mechanism by which cows perceive the magnetic field and the reasons for this particular reaction to it remain unclear.
In addition to the listed remarkable properties, the magnetic field contributes. They arise as a result of sudden changes in the field that occur in remote regions of the field.
The magnetic field was not ignored by supporters of one of the “conspiracy theories” - the theory of a lunar hoax. As mentioned above, the magnetic field protects us from cosmic particles. The "collected" particles accumulate in certain parts of the field - the so-called Van Alen radiation belts. Skeptics who do not believe in the reality of the moon landings believe that astronauts would have received a lethal dose of radiation during their flight through the radiation belts.
The Earth's magnetic field is an amazing consequence of the laws of physics, a protective shield, a landmark and the creator of auroras. If it weren't for it, life on Earth might have looked completely different. In general, if there were no magnetic field, it would have to be invented.
A team of scientists led by Simon Anzellini made a new discovery. During some experiments, they established new qualities of the solid part of the earth's core
Scientists have found that the iron core of the earth is heated to 6 thousand degrees Celsius, and this information is a thousand degrees higher than previously thought. And this fact now allows us to understand the nature of the magnetic field of our planet.
Simon Ancellin, a member of the French Commissariat for Atomic Energy in Grenoble, and his colleagues were able to calculate the temperature of the Earth's iron core by observing the behavior of iron under ultra-high pressure.
A group of scientists used their own method to determine the properties of iron. A piece of iron was placed inside a diamond anvil and compressed under a pressure of 2.2 million atmospheres, and then heated by a laser beam to 4.5 thousand degrees Celsius.
The experiment was carried out to obtain data that will help scientists determine the temperature of the solid part of the earth's core, in which the pressure reaches 3.3 million atmospheres. To the surprise of scientists, the temperature in the core reached 6-6.5 thousand degrees Celsius, which exceeds earlier ideas by a thousand degrees. As scientists say, the new discovery fits well into the general understanding of scientists about the nature and structure of the planet. And it allows us to explain the cause of the Earth’s magnetic field.
Source of the Earth's magnetic field
The history of the study of the issue of terrestrial magnetism begins in 1600, when the work of William Gilbert, the court physician of the English Queen Elizabeth I, was published, and it was called “On the Magnet, Magnetic Bodies and the Great Magnet - the Earth.” The essence of the work is that the scientist comes to the conclusion that the Earth is a large dipole magnet.
Until the 17th century, this work was the main work on geomagnetism. From the 17th to the 20th centuries, many studies and observations began to take place, which led scientists to new conclusions and properties. At this time, the work of such scientists as Halley Halley, Alexander von Humboldt, Joseph Gay-Lussac, James Maxwell, Carl Gauss is celebrated.
The formation of the theory of electromagnetism by Maxwell in the 70s of the 19th century is quite significant. From his equations it turns out that the magnetic field is formed by electric current. Consequently, this leads to the equivalence of closed elementary currents and magnetic dipoles, the moment of which is also called the magnetic moment of the current. When added, these quantities form, say, the magnetic field of a cylindrical magnet, which is approximately equal to the field of a solenoid of the same length and the same cross-section.
But at the moment, there was no clear idea of where the Earth's magnetic field comes from. Modern scientific works on the nature of geomagnetism indicate the following: “Now, turning to the “big magnet,” the matter at first glance is not so difficult: to find in the middle of the planet current systems of the required configuration and forces that form a field on the surface of the Earth, the structure of which we have studied well. When we head inside the Earth, after passing through the crust, upper mantle and lower mantle, we will reach a huge liquid core, the existence of which was determined in the mid-20th century by Harold Jeffreys of the University of Cambridge.The actual liquid state of a large part of the core provides the conclusion of the mechanism for generating the geomagnetic field. The point is that the permanent magnetic field of the Earth is formed by electric currents that appear during the movement of a conducting fluid in the core.Another theory on this issue has not yet been invented.
When we go further and try to understand the essence of the processes of generating the Earth’s geomagnetic field, then it’s time to use the dynamo mechanism for this purpose. In short, we will assume that the formation of a magnetic field in the outer liquid core of the Earth is carried out in the same way as in a self-excited dynamo, where a coil of wires rotates in an external magnetic field. Consequently, due to electromagnetic induction, an electric current arises in the coil and forms its own magnetic field. It increases the external magnetic field, and the current in the coil also increases.
Naturally, the liquid core of the planet is not a dynamo. But when thermal convection appears in a liquid conductor, a certain system of flows of electrically conductive liquid is formed, which is consonant with the movement of the conductor. It would not be gross violence against nature to assume the existence of certain seed magnetic fields in the nucleus. Consequently, if a liquid conductor, during its relative motion, crosses the lines of force of these fields, then an electric current is formed in it, creating a magnetic field, which increases the external seed field, and this, in turn, increases the electric current and so on, like the song about the pope and his dog, who carelessly ate a piece of meat. The process will continue until a stationary magnetic field is established, when various dynamic processes balance each other."
The earth's magnetic field is the energy of the future
Those who are interested in the history of science and technology certainly know about Tesla's electric car. As historiographical reports state, this car moved thanks to an electric motor, and it drew energy from the space around it. Developers of space systems have long been trying to find its practical application.
Russian scientist Candidate of Physical and Mathematical Sciences Evgeny Timofeev, an employee of RSC Energia, has been working on this problem for many years. He has already managed to create a prototype of such a generator that would generate energy from the Earth's magnetic field. The generator works like this: when the device is set in motion, a sensitive voltmeter registers the occurrence of electromotive force in the circuit. The inventor clarifies that the method of operation of the device is based on the intersection of the Earth's magnetic field with a solenoid, some part of the winding of which is protected by a magnetic shield.
As the scientist states, in terms of practical use of the energy of sunlight, humanity is already much further ahead than the use of the Earth's magnetic field. In some aspects we are at the same level Tesla was at 75 years ago.
What the Earth's magnetic field is needed for, you will learn from this article.
What is the value of the Earth's magnetic field?
First of all, it protects artificial satellites and the inhabitants of the planet from the action of particles from space. These include charged, ionized particles of the solar wind. When they enter our atmosphere, the magnetic field changes their trajectory and directs them along the field line.
In addition, we entered the era of new technologies thanks to our magnetic field. All modern, advanced devices that operate using a variety of memory storage devices (disks, cards) depend directly on the magnetic field. Its tension and stability directly affects absolutely all information and computer systems, since all the information necessary for their proper operation is located on magnetic media.
Therefore, we can say with confidence that the prosperity of modern civilization, the “viability” of its technologies closely depends on the state of the magnetic field of our planet.
What is the Earth's magnetic field?
Earth's magnetic field is the area around the planet where magnetic forces act.
As for its origin, this issue has not yet been finally resolved. But most researchers are inclined to believe that our planet owes its magnetic field to its core. It consists of an inner solid and an outer liquid part. The rotation of the Earth contributes to constant currents in the liquid core. And this leads to the emergence of a magnetic field around them.
Most of the planets in the solar system have magnetic fields to varying degrees. If you place them in a row in order of decreasing magnetic dipole moment, you will get the following picture: Jupiter, Saturn, Earth, Mercury and Mars. The main reason for its occurrence is the presence of a liquid core.
