Magician field of land. What is the magnetic field of the Earth? Origin of magnetic field

According to modern ideasIt was formed about 4.5 billion years ago, and from now on our planet surrounds the magnetic field. All that is on Earth, including people, animals and plants, are exposed to its effect.

The magnetic field extends to a height of about 100,000 km (Fig. 1). It deflects or captures solar wind particles, destroying for all living organisms. These charged particles form the radiation belt of the Earth, and the whole area of \u200b\u200bthe near-earth space in which they are called, called magnitosphere (Fig. 2). With the light-lit side of the Earth, the magnetosphere is limited to a spherical surface with a radius of about 10-15 radius of the Earth, and on the opposite side it is stretched like a comette tail at a distance of up to several thousand radius of the Earth, forming a geomagnetic tail. The magnetosphere is separated from the interplanetary field by the transition region.

Magnetic poles of land

The axis of the earth magnet is tilted in relation to the axis of rotation of the Earth by 12 °. It is located about 400 km away from the center of the Earth. The points in which this axis crosses the surface of the planet - Magnetic poles. Magnetic poles do not coincide with true geographic poles. Currently, the coordinates of magnetic poles are as follows: Northern - 77 ° S.Sh. and 102 ° zd; South - (65 ° Yu.Sh. and 139 ° V.D.).

Fig. 1. Building magnetic field Earth

Fig. 2. The structure of the magnetosphere

Power lines coming from one magnetic pole to another are called magnetic meridians . Between the magnetic and geographical meridian, an angle is formed, called magnetic declination. Every place on Earth has its own angle of declination. In the district of Moscow, the decline angle is 7 ° to the east, and in Yakutsk - about 17 ° west. This means that the northern end of the compass arrow in Moscow deviates to the right of the geographical meridian passing through Moscow, and in Yakutsk - at 17 ° to the left of the corresponding meridian.

A freely suspended magnetic arrow is located horizontally only on the line of the magnetic equator, which does not coincide with the geographical. If you move north of the magnetic equator, the north end of the arrow will gradually fall. Angle formed by a magnetic arrow and a horizontal plane called magnetic challenge. In the north and southern magnetic poles magnetic inclination is the largest. It is 90 °. On the northern magnetic pole, a freely suspended magnetic arrow will be installed vertically the northern end of down, and on the southern magnetic pole its south end drops down. Thus, the magnetic arrow shows the direction of the power lines of the magnetic zero above the ground surface.

Over time, the position of magnetic poles relative to ground surface Changes.

The magnetic pole was opened by the researcher James K. Ross in 1831 in hundreds of kilometers from its current location. On average, in one year it moves 15 km. IN last years The speed of moving magnetic poles has increased dramatically. For example, the northern magnetic pole is now moving at a speed of about 40 km per year.

Change of magnetic poles of the earth is called magnetic field inversion.

For geological history Our planet earth magnetic field has changed its polarity more than 100 times.

The magnetic field is characterized by tension. In some places of the Earth, the magnetic power lines deviate from the normal field, forming anomalies. For example, in the area of \u200b\u200bthe Kursk magnetic anomaly (CMA), the field strength is four times higher than the norm.

There are daily changes in the magnetic field of the Earth. The reason for these changes in the magnetic field of the Earth - electrical toxes current in the atmosphere at high height. They are caused sollar radiation. The floor of the solar wind by the magnetic field of the Earth is distorted and acquires a "loop" in the direction from the Sun, which extends hundreds of thousands of kilometers. The main reason for the emergence of the solar wind, as we already know, are the grand emissions of the substance from the crown of the Sun. When moving to the ground, they turn into magnetic clouds and lead to strong, sometimes extreme perturbations on Earth. Especially strong disturbances of the magnetic field of the Earth - magnetic storms. Some magnetic storms begin unexpectedly and almost simultaneously throughout the land, while others develop gradually. They can continue a few hours and even the day. Often, magnetic storms occur 1-2 days after solar flash due to ground passing through the flow of particles thrown by the Sun. Based on the delay time, the speed of such a corpuscular stream is assessed several million km / h.

During strong magnetic storms, the normal operation of the telegraph, telephone and radio is disturbed.

Magnetic storms are often observed on a latitude of 66-67 ° (in the zone of polar beams) and arise simultaneously with polar shines.

The structure of the magnetic field of the Earth varies depending on the latitude of the terrain. The permeability of the magnetic field increases towards the poles. Over the polar regions, the power lines of the magnetic field are more or less perpendicular to the earth's surface and have a funnel configuration. Through them, part of the solar wind from the day side penetrates the magnetosphere, and then in the upper atmosphere. Here, during the magnetic storm, particles from the tail part of the magnetosphere, reaching the boundaries of the upper atmosphere in high latitudes of the northern and southern hemispheres, are fixed. It is these charged particles that the polar beams cause here.

So, magnetic storms and daily changes of magnetic zero are explained, as we have already found out, solar radiation. But what is the main reason that creates the constant magnetism of the Earth? Theoretically managed to prove that 99% the Earth's magnetic field causes sources hidden inside the planet. The main magnetic field is due to sources located in the depths of the Earth. They can be divided into two groups. Their main part is associated with processes in the earth's core, where, due to continuous and regular movements of the electrically conductive substance, an electrical current system is created. The other is due to the fact that rocks The earth's crust, magnetizing the main electric field (core field), create an eating magnetic field, which is summed with the magnetic field of the kernel.

In addition to the magnetic field around the Earth there are other fields: a) gravitational; b) electric; c) thermal.

Gravitational field The lands call the field of gravity. It is aimed at a plunder perpendicular to the geoid surface. If the earth had the figure of the ellipsoid of rotation and would be evenly distributed in it, then it had a normal gravitational field. The difference between the strength of the real gravitational field and theoretical - an anomaly of gravity. Different material composition, the density of rocks causes these anomalies. But other reasons are possible. They can be explained by the following process - equiliblation of solid and relatively light crust on a heavier upper mantle, where the pressure of the overlying layers is equalized. These flows cause tectonic deformations, the movement of lithospheric plates and thereby create a macro-relief of the Earth. Gravity strength holds the atmosphere, hydrosphere, people, animals on Earth. Gravity must necessarily take into account when studying processes in geographic shell. Term " geotropism»Called the growth of plants organs, which, under the influence of earth's strength, always provide the vertical direction of the growth of the primary root perpendicular to the surface of the Earth. Gravitational biology uses plants as experimental objects.

If you do not take into account the power of gravity, it is impossible to calculate the source data for the launch of missiles and spacecraft, Make gravimetric intelligence of ore fossils and, finally, it is impossible to further develop astronomy, physics and other sciences.

In 1905, Einstein called one of the five main mysteries of the then physicists of the cause of earthly magnetism.

In the same 1905, the French Geophysicist Bernard Brynez spent in the Southern Department of Cantal Memal of Magnetism of the Lavova sediments of the Pleistocena era. The magnetization vector of these breeds was almost 180 degrees with a planetary magnetic field vector (its compatriot P. David received similar results even a year earlier). Bryols came to the conclusion that three-quarters of a million years ago during the outpouring of Lava, the direction of geomagnetic power lines was the opposite of modern. So the effect of inversion (polarity circulation) of the Earth's magnetic field was discovered. In the second half of the 1920s, Bryrya's conclusions were confirmed by P. L. Merkanton and Monotori Matuyam, but these ideas were recognized only by the middle of the century.

Now we know that the geomagnetic field exists at least 3.5 billion years and during this time the magnetic poles thousands were exchanged in places (Broers and Matuyam investigated the last time inversion, which now wears their names). Sometimes the geomagnetic field retains orientation within tens of millions of years, and sometimes no more than five hundred centuries. The inversion process itself usually takes several millennia, and on its completion, the field strength, as a rule, does not return to the previous value, and varies a few percent.

The geomagnetic inversion mechanism is not quite clear and today, and a hundred years ago, he did not allow a reasonable explanation at all. Therefore, the opening of Bryols and David only reinforced Einstein assessment - indeed, earthly magnetism was extremely mysterious and incomprehensible. But by the time he was investigated by over three hundred years, and in the XIX century they were engaged in such stars of European science, as a great traveler Alexander von Humboldt, a brilliant mathematician Karl Friedrich Gauss and a brilliant physicist Experimentator Wilhelm Weber. So Einstein was truly looked at the root.

What do you think, how much is our planet magnetic poles? Almost everyone will say that two are in the Arctic and Antarctic. In fact, the answer depends on the definition of the concept of the pole. The geographic poles consider the intersection points of the earth's axis with the surface of the planet. Since the earth rotates as solid, there are only two such points and do not come up with anything else. But with magnetic poles the situation is much more complicated. For example, a pole can be considered a small area (ideally a point again), where the magnetic power lines are perpendicular to the earth's surface. However, any magnetometer registers not only the planetary magnetic field, but also fields of local rocks, electrical currents of the ionosphere, solar wind particles and other additional sources of magnetism (and their average share is not so small, about a few percent). The more precisely the device, the better it does - and therefore it makes it difficult to allocate the true geomagnetic field (it is called the mainstream), the source of which is in earth depths. Therefore, the coordinates of the pole defined by direct measurement are not distinguished by stability even for a short period of time.

You can act differently and establish the position of the pole on the basis of certain models of earthly magnetism. In the first approximation, our planet can be considered a geocentric magnetic dipole, whose axis passes through its center. Currently, the angle between her 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 in the direction of the northwestern part Pacific Ocean Approximately 540 km (this is an eccentric dipole). There are other definitions.

But that's not all. The earth's magnetic field does not really have dipole symmetry and therefore has multiple poles, and in a huge amount. If you consider the earth with a magnetic four-pole, quadrupole, you will have to introduce two poles in Malaysia and in the southern part of the Atlantic Ocean. Okletaite model sets the eight of the poles, etc. The modern most advanced models of earthly magnetism operate as much as 168 poles. It is worth noting that during the inversion only the dipole component of the geomagnetic field temporarily disappears, and others change much weaker.

Poles on the contrary

Many know that the generally accepted names of the poles are true to the opposite. In the Arctic there is a pole, which indicates the northern end of the magnetic arrow, - therefore, it would be worth it to be southern (the poles of the same name are repelled, the variepetes are attracted!). Similarly, the northern magnetic pole is based in high latitudes of the southern hemisphere. Nevertheless, by tradition, we call the pole in accordance with geography. Physics have long been agreed that the power lines go out of north Pole Any magnet and are included in the South. It follows that the lines of earthly magnetism leave the southern geomagnetic pole and are tightened to the North. Such is the Convention, and it is not worth violating it (it's time to remember the sad experience of Panikovsky!).

Magnetic pole, as it will define it, does not stand still. The North Pole of the Geocentric Dipole in 2000 had coordinates of 79.5 N and 71.6 W, and in 2010 - 80.0 N and 72.0 W. The True North Pole (the one that physical measurements detect) 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, he did not more than 10 km a year, but after 1980 suddenly began to move much faster. In the early 1990s, its speed exceeded 15 km per year and continues to grow.

As told "Popular Mechanics" former leader Geomagnetic laboratory of the Canadian Geological Research Service Lawrence Newitt, now the true pole migrates to the north-west, moving annually by 50 km. If the vector of his movement does not change for several decades, then by the middle of the XXI century it will be in Siberia. According to the reconstruction, made several years ago by the same New Lettt, in XVII and XVIII centuries The North Magnetic Pole preferably shifted to the southeast and only in about 1860 turned to the north-west. True South Magnetic Pole The last 300 years is moving in the same direction, and its average-scale displacement does not exceed 10-15 km.

Where does the Earth have a magnetic field? One of the possible explanations is simply striking. The Earth has an internal solid iron-nickel nucleus, the radius of which is 1220 km. Since these metals are ferromagnetic, why not assume that inner kernel has static magnetization, which ensures the existence of a geomagnetic field? Multipolarity of earthly magnetism can be written off to the asymmetry of the distribution of magnetic domains inside the kernel. The migration of the poles and inversion of the geomagnetic field is more difficult to explain, but probably you can try.

However, nothing happens. All ferromagnets remain those (that is, they retain spontaneous magnetization) only below a certain temperature - the point of Curie. For iron, it is 768 ° C (nickel is much lower), and the temperature of the internal nucleus of the Earth significantly exceeds 5000 degrees. Therefore, with a hypothesis of static geomagnetism, it is necessary to part. However, it is possible that there are cooled planets with ferromagnetic nuclei in space.

Consider another opportunity. Our planet also has a liquid external core with a thickness of approximately 2300 km. It consists of melt of iron and nickel with an admixture of lighter elements (sulfur, carbon, oxygen, and possibly nobody knows radioactive potassium. The temperature of the lower part of the outer kernel almost coincides with the temperature of the inner core, and in the upper zone on the border with mantia, it drops to 4400 ° C. Therefore, it is quite natural to assume that due to the rotation of the Earth, there are circular flows there, which may cause terrestrial magnetism.

Convective Dynamo

"To explain the occurrence of a poloidal field, it is necessary to take into account the vertical streams of the substance of the nucleus. They are formed by convection: the heated iron-nickel melt pops up from the bottom of the kernel towards the mantle. These jets are tightened by Coriolis's force like airflows of cyclones. In the northern hemisphere, the ascending flows rotate clockwise, and in South - against, - explains the professor of the California University Gary Glovetzmeer. - Using the approach to the mantle, the substance of the nucleus cools and begins the return movement inland. Magnetic fields of ascending and downward flows are quenched by each other, and therefore the field is not installed by vertical. But in the upper part of the convection jet, where it forms a loop and is shortly moving horizontally, the situation is different. In the northern hemisphere, the power lines, which were watching the West to the convection climb, turn clockwise at 90 degrees and focus north. In the southern hemisphere, they turn from the east counterclockwise and are also sent to the north. As a result, in both hemispheres, a magnetic field is generated, indicating south to the north. Although this is not the only one possible explanation The occurrence of a poloidal field, he is considered the most likely. "

It is such a scheme of geophysic scientists who discussed 80 years ago. They believed that the streams of the conductive fluid of the external core due to its kinetic energy generate electrical currents covering ground axle. These currents generate a magnetic field predominantly dipole type, the power lines of which on the surface of the earth are stretched along the meridians (such a field is called poloidal). This mechanism causes an association with the work of the Dynamo Machine, from here and its name occurred.

The described scheme is beautiful and visual, but unfortunately, erroneous. It is based on the assumption that the movement of the substance of the outer nucleus is symmetrically relative to the earth's axis. However, in 1933, English Mathematics Thomas Kawling proved the theorem according to which no axisymmetric flows are able to ensure the existence of a long-term geomagnetic field. Even if it appears, then the age of it will be a shortage, ingesting thousands of times less than the age of our planet. Need a model more complicated.

"We do not know exactly when earthly magnetism arose, but it could happen soon after the formation of a mantle and an external core," says one of the largest specialists in planetary magnetism, Professor of Californias technological Institute David Stevenson. - To enable geodinamo, an external seed field is required, and not necessarily powerful. This role, for example, could take on the magnetic field of the Sun or the fields of currents generated in the kernel at the expense of the thermoelectric effect. Ultimately, it is not too important, there were enough sources of magnetism. With such a field and circular Movement The flow of conductive fluid launch of the intrapalanet dynamomoshina became simply inevitable. "

Magnetic defense

Monitoring of earthly magnetism is produced using an extensive network of geomagnetic observatories, the creation of which began in the 1830s.

For the same purposes, ship, aircraft and space devices are used (for example, scalar and vector magnetometers of the Ersted Danish satellite operating since 1999).

The tension of the geomagnetic field varies from approximately 20,000 nanotela near the coast of Brazil to 65,000 Nanotela in the South Magnetic Pole area. Since 1800, his dipole component decreased by almost 13% (and from the middle of the XVI century - by 20%), while the quadrupole has increased somewhat. Paleomagnetic studies show that for several millennia before the start of our era, the tensions of the geomagnetic field stubbornly climbed upwards, and then began to decline. Nevertheless, the current planetary dipole moment significantly exceeds its average value over the past one and a half million years (in 2010, the results of paleomagnetic measurements were published, testifying that 3.5 billion years ago, the earth's magnetic field was twice as weaker than the current one). This means that the whole history of human societies from the emergence of the first states to our time has accounted for the local maximum of the earth's magnetic field. It is interesting to think about whether it affected the progress of civilization. Such an assumption ceases to seem fantastic, if we consider that the magnetic field protects the biosphere from cosmic radiation.

And here's another circumstance that is worth noting. In adolescence and even the adolescence of our planet, all the substance of her nucleus was in the liquid phase. The solid inner kernel was formed relatively recently, perhaps just a billion years ago. When this happened, convection flows became more ordered, which led to more sustainable geodinamo operation. Because of this, the geomagnetic field won in magnitude and stability. It can be assumed that this circumstance has favorably affected the evolution of living organisms. In particular, the strengthening of geomagnetism has 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 of such a launch. Suppose for simplicity, the seed field is almost parallel to the axis of the rotation of the Earth (in fact, it is enough if it has a nonzero component in this direction, which is almost inevitable). The speed of rotation of the substance of the outer core decreases as the depth decreases, and due to its high electrical conductivity, the power lines of the magnetic field move along with it - as physicists say, the "enclosed" field on Wednesday. Therefore, the strength lines of the seed field will bend, leaving ahead at large depths and lagging behind the smaller. In the end, they will stretch and deform so much that they will give the beginning of a toroidal field, a circular magnetic loop covering the earth's axis and directed in opposite parties in the northern and southern hemispheres. This mechanism is called W-effect.

According to Professor Stevenson, it is very important to understand that the toroidal field of the external nucleus arose due to the poloidal seed field and, in turn, spawned a new poloidal field, observed in the earth's surface: "Both types of planetary geodinamo fields are interrelated and cannot exist without each other." .

15 years ago, Gary Glovetzmeyer, together with Paul Roberts, published a very beautiful computer model of the geomagnetic field: "In principle, an adequate mathematical apparatus has long been an adequate mathematical apparatus - magnetic hydrodynamic equations plus equations that describe the power of gravity and heat flow inside the earth's core. Models based on these equations were very complex, but they can be simplified and adapted for computer computing. That is what we did with Roberts. The run on the supercomputer made it possible to construct a self-consistent description of the long-term evolution of the speed, temperature and pressure of the flow of the substance of the outer core and the associated evolution of magnetic fields. We also found out that if you lose the simulation at the time intervals of about dozens and hundreds of thousands of years, then the geomagnetic field inversion arise. So in this regard, our model has been not bad for the magnetic history of the planet. However, there is a difficulty that has not yet been eliminated. The parameters of the substance of the external kernel, which are laid in such models, are still too far from real conditions. For example, we had to accept that its viscosity is very large, otherwise there are no resources of the most powerful supercomputers. 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 and turbulence that undoubtedly takes place. But computers are gaining strength every year, and many more realistic simulations will appear in ten years. "

"The work of geodinamo is inevitably associated with chaotic changes in the streams of iron-nickel melt, which turn into magnetic field fluctuations," Professor Stevenson adds. - Inversion of earthly magnetism is just the strongest of possible fluctuations. Since they are stochastic by their nature, it is unlikely that they can be predicted in advance - in any case we can not be able to ".

In 1600, English scientist William Hilbert in his book "About the magnet, magnetic bodies And the big magnet - the earth. " I presented the land as a gigantic permanent magnet, the axis of which does not coincide with the axis of rotation of the Earth (the angle between these axes is called magnetic decline).

Hilbert confirmed his assumption on the experience: he pulled out of a natural magnet big Shar And, bringing the magnetic arrow to the surface of the ball, showed that it is always installed in the same way as the compass arrow on the 3 hours.

A graphically magnetic field of the earth is similar to the magnetic field of a permanent magnet.

In 1702, E. Galli creates the first magnetic land cards.
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The main reason for the presence of a magnetic field of the Earth is that the land core consists of a hot iron (a good conductor of electric currents arising inside the Earth).
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The magnetic field of the Earth forms a magnetosphere that extends to 70-80 thousand km to the direction of the Sun. It shields the surface of the Earth, protects against the harmful effects of charged particles, high energies and cosmic rays, determines the nature of the weather.
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The magnetic field of the sun is 100 more than the earth.

Magnetic Field Changes

Back in 1635, Hellibrand establishes that the magnetic field of the Earth changes.
Later it was established that there are constant and short-term changes in the magnetic field of the Earth.

The reason for constant changes is the presence of mineral deposits.
On Earth there are such territories where its own magnetic field is very distorted by the occurrence of iron ores. For example, Kursk magnetic anomaly located in the Kursk region.

The cause of short-term changes in the magnetic field of the Earth is the action of "solar wind", i.e. The effect of the flow of charged particles emitted by the sun. The magnetic field of this flow interacts with the magnetic field of the Earth, "magnetic storms" occur.
The frequency and force of magnetic storms affects solar activity.
During the maximum of solar activity (once every 11.5 years), such magnetic storms arise that radio communication is broken, and the arrows of the compasses begin to be unpredictable "dance".

The result of the interaction of charged particles of "solar wind" with the atmosphere of the Earth in northern latitudes is such a phenomenon as "polar shine".

Do not confuse magnetic and geographical poles of the Earth

The magnetic poles are repelled, and the variepetes are attracted.
Why does the compass arrow with its north pole shows north, and South - south?

What ends of the compass arrows attracts to the North Pole of the Earth?
Or, in other words, which of the two Earth Poles is the North or South - lies on the side where the northern end of the magnetic arrow indicates?
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The right is the one who says that the northern end of the magnetic arrow indicates to the North Pole of the Earth (geographical).
And this means that in the north of the land is the Southern Magnetic Pole of the Earth, its coordinates of 75 °, 6 s. sh., 101 ° z. d. (Data for 1965).

The North Magnetic Pole of the Earth is in Antarctica, its coordinates of 66 °, 3 Yu.Sh., 141 ° C. d. (according to data for 1965).
Earth magnetic poles slowly drift.

Is North in the north?

Man, looking at the compass, steps straight to the other side where the magnetic arrow indicates a dark end. He "goes on the compass" to the north to the pole where will he come?

Most of course made the same mistake.
They thought that a person had to come to the Northern Geographical Pole of the Earth.
And in fact, he arrived at Somerset Island, located on the northern tip of North America, where the Northern Magnetic Pole of the Earth is located.

Currently, the South Magnetic Pole of the Earth is located in Canada at a distance
About 2100 km from the Geographical North Pole.

INTERESTING

In which place the land absolutely impossible to believe the magnetic arrow due to the fact that it shows the northern end of the south, and southern north?

By placing the compass between the northern magnetic and northern geographic poles (closer to the magnetic), we will see that the north end of the arrow is directed to the first, that is, south, and the South - in the opposite direction, that is, north.

Scientists have determined that at the points of the magnetic pole of the Earth freely suspended on the thread, the magnetic arrow should be installed vertically, since it is at these points that magnetic lines are included (or output) from the ground.

Effect of Earth Magnetic Field on Living Organisms

The magnetic field of the Earth serves many living organisms for orientation in space.
Some sea bacteria are located in the bottom ILE at a certain angle to the power lines of the Earth's magnetic field, which is explained by the presence of small ferromagnetic particles in them.
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Flies and other insects "sit down" preferably in the direction across or along the magnetic lines of the magnetic field of the Earth. For example, termites are located on rest so that they are heads in one direction: in some groups - in parallel, in others - perpendicular to the magnetic field lines.
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The landmark for migratory birds also serves the magnetic field of the Earth. Recently, scientists have learned that the birds in the eye in the area there is a small magnetic "compass" - a tiny tissue field, in which magnetite crystals are located with the ability to magnify in the magnetic field.
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Botany established plant susceptibility to magnetic fields. It turns out a strong magnetic field affects the growth of plants.

Always arose the question of how the compass works? And today we will talk about such things as the magnetic field of the Earth. And since, unfortunately, the editor is limited in time, but I want to give something interesting, we will tell you about "earthly magnetism" with the help of several different sources.

So:

The magnetic field of the Earth has remained a mystery for a long time, because stone magnets do not happen, right? But as soon as you open that there is a volatile amount of iron inside the Earth, everything seems to be in place. Iron does not form a "permanent" magnet like attached to plastic piglets and bearings, which we, without knowing why, buy to attach to the refrigerator. Earthly subsoil more like Dynamo. By the way, this is called - geomagnetic dynamo. As we have already mentioned, iron in the core of the Earth is largely in the molten state, with the exception of a solid dense "ball" in the center itself. The liquid part still continues to heat up. Previously, this phenomenon was explained by the fact that radioactive elements, being dense of the rest in chemical composition The planets, plunged into the most center, being locked there, and heat gives radioactive energy emitted by them. The modern theory offers a completely different explanation: the liquid part of the nucleus is heated, because hard - cools. The molten iron on contact with the solid nucleus itself is thinning itself, while heat is released. This heat should go somewhere, it cannot simply disappear, as if the blow of warm air, - around a thousand miles of a solid rock. The heat is transmitted to the molten kernel layer, heating it.

Perhaps you will be surprised by the fact that the part that comes into contact with the solid core can be cooled and harden and, at the same time, heated during this solidification. Explanation Simple: Hot molten iron rises up as heating. Recall the balloon. When you heat the air, it rises. This is because when heated air expands, it becomes less dense, and less dense substances pop up over more denser. Balloon He holds the air in a huge silk bag, often bright painted and painted by emblems of banks or real estate agencies, and rises with air. Hot iron is not painted with anything, but rises in the same way as hot air, removing from the solid core. It slowly pops up, cooling, and then when it becomes too cold, more precisely relatively Cold, begins to dive into depth. As a result, the earth's core is in continuous motion, raving inside and cooling outside. It cannot be climbing all over, that is, the same kernel areas pop up, while others are rebuilt. This type of circulating heat transfer is called convection.

According to physicists, under the observance of some three conditions, moving fluids can create a magnetic field. In? First, the liquid should carry out an electric current, and iron is fine with it. In? The second, initially there should be at least a small magnetic field, and there are weighty grounds to believe that our land, then still very young, was inherent in a certain Tolik of personal magnetism. In? Third, something should rotate this liquid, distorting the original magnetic field, and in the Earth this rotation occurs due to the power of Coriolis, similar to centrifugal powerHowever, the acting more weak and arising from the rotation of the Earth around its axis. Roughly speaking, rotation distorts the initially weak magnetic field, spinning it as spaghetti on the plug. Then magnetism rises upstairs caught by the pop-ups of the iron kernel. As a result of all this deception, the magnetic field becomes much stronger.

Yes, in some sense, it can be said that the Earth behaves like inside she has a huge magnet, but in fact everything is much more complicated. In order to slightly specify the drawn picture, we recall that there are at least seven other factors resulting in the presence of the magnetic field. So, some components of the earth's crust can be permanent magnets. Like the arrow of the compass, pointing to the north, they gradually lined up along a stronger geomagnetic dynamo, further enhancing it. In the upper layers of the atmosphere, there is a layer of charged ionized gas. Before satellites were invented, the ionosphere played a crucial role in providing radio communications: radio waves were reflected from charged gas, and did not go into space. The ionosphere is in motion, and moving electricity creates a magnetic field. At an altitude of approximately 15,000 miles (24,000 km) flows the ring current - layer of ionized low-density particles forming a huge torus. This slightly weakens the power of the magnetic field of the Earth.

The following two factors are the so-called magnetopause and a magnetic tail, which arose under the influence of the solar wind on the Earth's magnetosphere. Sunny wind is a constant flow of particles emitted by the hyperactive sun. Magnetopause is a head wave of a terrestrial magnetic field, which comes against the solar wind, and the magnetic tail is a trail of this wave from the opposite side of the planet, where the Earth's own magnetic field is "drown" outward, besides, destroying under the influence of solar wind. In addition, the solar wind causes a kind of craving along the Earth's orbit, creating an additional distortion of the magnetic field lines, known as the longitudinal current in the magnetosphere. And finally, there are Avrral streams. Northern Lights, or Aurora Borealis, is delicious, mysterious pale light panels that are transfusing in the Northern Polar Sky. A similar performance, Aurora Australis, can be observed near the southern pole. Polar radiances are created by two stripes electric currentflowing from magnetopause in a magnetic tail. This, in turn, creates new magnetic fields and two electrical streams - Western and oriental.

So speak, Earth is just a big magnet? Well, yes, and the ocean is a bowl with water.

Magnetic materials found in ancient rocks indicate that from time to time the magnetic field of the Earth changes its polarity, the northern magnetic pole becomes southern and vice versa. This happens about once every half a million years, although the strict pattern to trace never succeeded. Nobody knows why this happens, however, mathematical models show that the magnetic field of the Earth can be focused equally and in the same direction, and none of them is stable. Any position is sooner or later losing stability and transmits the relay stick as the opposite. Transitions occur quickly for about 5 thousand years, while periods between them are a hundred times longer.

Magnetic fields are available in most planets, and this fact is even more complicated than the earth's field. We will have to learn more about the planetary magnetism.

Alfred Vegener

One of the most impressive properties of our planet was discovered in 1912, but was not taken into account up to 60? X. The most convincing evidence in its favor was the change of magnetic poles. It is about the fact that earth continents do not stand still, but slowly drifted on the surface of the planet. According to the German scientist Alfred Vegener, the first to publish your theory, the current individual continents used to be one supermanite, which he called Pangea (that is, "the whole earth"). It existed about 300 million years ago.

Surely Vegener was not the first to think before. His idea, at least partly, arose under the influence of the amazing similarity of the outlines of the shores of Africa and South America. On the map, this is especially striking. Naturally, Vegenter relied on other data. He was not a geologist, but a meteorologist, an ancient climate specialist, and it was surprised that in the regions with a cold climate, rock rocks were found, which clearly emerged in the regions with warmth, and vice versa. For example, in Sahara, it is still possible to find the remains of the ancient glaciers whose age is 420 million years old, and in Antarctica - petrified ferns. In those days, anyone would be said to him that the climate simply changed. However, Vegegen was convinced that the climate remained practically the same, with the exception of the ice age, and changed, that is, the continents themselves moved. He assumed that they were divided as a result of convection in the earthly mantle, but was not sure about that.

This idea was considered insane, especially since she was not a geologist, and besides, Vegener ignored all the facts that do not fit into his theory. And the fact that the similarity between Africa and South America Not so perfect, and the fact that the drift of the mainland was impossible to explain. Convection here is clearly at nothing, as it is too weak. Great A'Tuin(suspects that A'Tuin is a girl), maybe he carries the whole world on his back, but he is only a fiction, and in real worldIt seems that such forces are simply inconceivable.

The word is "unthinkable" we used not by chance. Many brilliant and respected scientists often repeat the same error. They confuse the expression "I do not understand how it may be" with "it is absolutely impossible." One of these, as it is asking for acknowledge one of us two, there was a mathematician, and the magnificent, but when his calculations showed that the earthly mantle could not move the continents, it did not even occur to him that the theories on which calculations were built were erroneous. His sir Harold Jeffers was called, and his problem was that he clearly lacked the flight of fantasy, because not only the outlines of the continents on both sides of the Atlantic coincided. From the point of view of geology and paleontology, everything was also converged. Take, for example, petrified the remains of the Besti mesozavrwho lived 270 million years ago at the same time in South America and Africa. It is unlikely that the Mesozavr overwhelmed the Atlantic Ocean, rather he just lived on Pangaye, having time to smire on both continents when they were not yet divided.

However, in the 60s years of the twentieth century, Vegegen's idea was recognized, and his theory of "drift continents" was established in science. At the meeting of the leading geologists, a certain young man named Edward Ballard, a very reminder dummigning Tupqi, and two of his colleagues demonstrated the possibilities of a new device called a computer. They instructed the car to find the best compliance not only between Africa and South America, but also North America, as well as Europe, given the possible, but small changes. Instead of taking the current outline coastlineThat from the very beginning it was not too brilliant idea, allowing opponents of the theory of the drift to argue that the continents do not coincide, young scientists used the contour corresponding to a depth of 3200 feet (1000 m) below sea level, since, in their opinion, it was less than erosion. The contours approached well, and geology is so simple. And although people at the conference still did not come to a single opinion, the theory of continental drift finally received certain recognition.

Today we have much more evidence and a clear idea of \u200b\u200bthe drift mechanism. In the central part of the Atlantic Ocean, halfway between South America and Africa, one of the middle ocean ridges stretched from the south (such, by the way, there are in all other oceans). Volcanic materials rise from the subsoil along the entire range, and then spread over its slopes. And so happens for 200 million years. You can even send a submarine and simply watch the process. Of course, all human life is not enough to notice this, but America is removed from Africa at a speed of 3/4 inches (2 cm) per year. At about the same speed, our nails grow, nevertheless, modern equipment is capable of registering these changes.

The most vivid proof of the continental drift was obtained due to the magnetic field of the Earth: rock rocks on both sides of the ridges have a curious pattern of magnetic bands, changing polarity from north to south and back, and the pattern on both slopes is symmetrical. This means that strips froze in a magnetic field as cool. When from time to time, the earth Dynamo changed its polarity, the rock rocks were magnetized in its field. Then, after separating the magnetized rocks, the same patterns were different as the ridge.

The surface of the earth is not a solid sphere. Both continents and the ocean bed are floating on huge, especially solid plates that can disperse on the parties when Magma is selected between them. (And most often this is due to convection in the mantle. Just Jeffreys did not know about the movement of the mantle of all that we know.) There are about a dozen plates, the six hundred (1000 km) width (1000 km) to six thousand (10,000 km) miles, And they turn all the time. Where their borders come into contact, drove and slide, earthquakes and volcanic eruptions are constantly occur. Especially in the Pacific Firewater, stretching throughout the perimeter of the Pacific Ocean and includes the western coast of Chile, Central America, the United States and on Japanese Islands and New Zealand. All of them are on the edge of one giant plate. Where the plates face, mountains arise: one slab is under the other and lifts her, fraction and smyster it. India is not at all part of the Asian continent at all, she just crashed into it, making the highest mountains in the world - Himalayas. She dispersed so much that still continues his movement, and the Himalayas grow.

(c) Science of the Flat World, Terry Pratchet, Jack Cohen, Aan Stewart (In general, read this book, better benefit In entertainment form, do not find (but before that, familiarize yourself in principle with a series of "flat world" pratchett in bibliographic not as a further order)).

Video magnetic field from Roscosmos:

How compass works

Who did not see a compass? A small one thing like a clock with one arrow. You twist it, you give up, and the arrow is stubbornly unfolded in one direction. The compass arrow is a magnet freely rotating on the needle. The principle of the operation of the magnetic compass is based on attraction-repulsion of two magnets. The opposite poles of magnets are attracted, the same names are repelled. Our planet is also such a magnet. His power is small, it is not enough to manifest themselves on a heavy magnet. However, the slight arrow of the compass, balanced on the needle turns and under the influence of a small magnetic field.

sports compass

What would the compass arrow dangle, and clearly showed the direction regardless of the shaking, it should be quite namagnichene. In sports compasses, the flask with the arrow is poured with liquid. Non-aggressive for plastic and metal parts that does not freeze at winter temperatures. Air bubble left in the flask carries the function pointer functions to orient the compass in the horizontal plane.

The championship in the study of the magnetic field of the Earth belongs to the English scientist William Hilbert. In his book "On magnet, magnetic bodies and a large magnet-land", published in 1600, he presented the Earth in the form of a giant permanent magnet, whose axis does not coincide with the axis of rotation of the Earth. The angle between the axis of rotation and the magnetic axis is called magnetic declination.

As a result of such a discrepancy, it is not entirely true that the compass arrow always indicates north. It indicates a point at a distance of 2100 km from the North Pole, on the island of Sommerset (its coordinates 75 °, 6 s. Sh., 101 ° z. D. - Data in 1965) The magnetic poles of the Earth slowly drifting. In addition to such an error in the direction of the arrow (we call it systematic), it is also impossible to forget about other causes of the compass improper operation:

• Metal objects or magnets located near the compass deflect its arrow
• Electronic devices that are sources of electromagnetic fields
• Mineral deposits - metal ores
• Magnetic storms occurring in the years of the strong activity of the sun distort the magnetic field of the Earth.

And now, try answering questions for smart:

In the meantime, you think, I will give a few interesting facts About the magnetic field of the Earth.

It turns out that it weakens about 0.5% every 10 years. According to various estimates, it will disappear after 1-2 thousand years. It is assumed that at this moment the ransom of the magnet - land will occur. After that, the field will start increasing again, but the northern and southern magnetic poles will be changed in places. It is believed that such a huge number of times happened to our planet.

It turns out that migratory birds also focus "according to the compass", more precisely, the magnetic field of the Earth serves as a guide. Recently, scientists have learned that the birds in the eye in the area there is a small magnetic "compass" - a tiny tissue field, in which magnetite crystals are located with the ability to magnify in the magnetic field.

The simplest compass can be made independently. To do this, you need to leave a sewing needle next to a magnet for several days. After that, the needle is magnetized. Moifling it with fat or oil, gently lower the needle to the surface of the water in a cup of water. Fat will not let her drown, and the needle will unfold from the north to south (well, or on the contrary :).

Impressed? Now, you can check your answers to questions:

• What do you think, where will the compass arrow indicate, if you are between the North Geographic Pole and the Northern Magnetic Pole?
  - The north end of the arrows will show .. south, and South - north!
• Where does the arrow show when the compass is located in the magnetic pole area?
  - It turns out that the arrow, suspended on the threads in the region of the magnetic pole, seeks to turn around ... down, along the magnetic lines of the Earth!
• If, guided by the compass, it is very long to go all the time strictly to the northeast, then where will come?
  - Come on the northern magnetic pole! Try to trace your path on the globe, a very interesting route is obtained.

and so it might look like a naval compass on the ship Columbus

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reference

Gauss (Russian GS designation, international - G) - unit of measurement of magnetic induction in the SSS system. Named in honor of German physics and mathematician Karl Friedrich Gauss.

1 Gs \u003d 100 mkl;

1 TL \u003d 104 GS.

It can be expressed through the main units of measurement of the SGS system as follows: 1 Gs \u003d 1 g 1/2. CM -1/2 .С -1.

Experience

A source: Textbooks of physics in magnetism, Berklievsky course.

Topic: M.agrit fields in substance.

Purpose: Find out how different substances react to a magnetic field.

Imagine some experiences with a very strong field. Suppose we made a solenoid with an internal diameter of 10 cm and 40 cm long.

1. The design of the coil creating a strong magnetic field. The cross section of the winding is shown in which cooling water flows. 2. Field curve in 2 on the axis of the coil.

Its external diameter is 40 cm and most of the space is filled with copper winding. Such a coil will provide a permanent field of 30,000 gsin the center, if you take 400 to it kwelectrical power and supply with water about 120 l. per minute to remove heat.

These specific data are given in order to show that although the device does not represent anything extraordinary, it is still a pretty authentic laboratory magnet.

The magnitude of the field in the center of the magnet is about 10 5 times the magnetic field of the Earth and, probably, 5 or 10 times the field near any magnetic iron rod or horseshoe magnet!

Near the center of the solenoid, the field is quite uniformly and is reduced by approximately twice on the axis near the ends of the coil.

conclusions

So, as experiments show, in such magnets the size of the field (that is, induction or tension) both inside the magnet and outside almost five orders of magnitude exceeds the magnitude of the land field.

Also, only twice - not "at times!" - It is smaller outside the magnet.

And at the same time, 5-10 times more power of an ordinary permanent magnet.

The average tension of the earth field on the surface is about 0.5E (5.10 -5 T.)

However, already in several hundred meters (if not dozens) from such a magnet, the compass magnetic arrow does not respond to any inclusion or turn off the current.

At the same time, it reacts well to the field of the Earth or its anomaly at the slightest change in position. What does it say about?

First of all, about an explicitly understated figure of the induction of the magnetic field of the Earth - that is, not the induction itself, but how we measure it.

We measure the reaction of the frame with the current, the angle of its rotation in the magnetic field of the Earth.

Any magnetometer is built on the measurement principle not directly, but indirectly:

Only by the nature of the change in the value of tension;

Only on the surface of the Earth, near her in the atmosphere and in the Middle Space.

The source of the field with a specific maximum we do not know. We measure only the difference between the size of the field at different points, and the tension gradient does not change too much with a height. No mathematical calculations with a maximum definition when using a classic approach do not work here.

Effect of magnetic field - experiments

It is known that even strong magnetic fields do not have virtually no effect on chemical and biochemical processes. You can put your hand (without manual hours!) In a solenoid with a field in 30 kgfwithout any noticeable consequences. It is difficult to say to which class of substances your hand belongs to Paramagnets or diamagnets, but the force acting on it will be, in any case, no more than several grams. Whole generations of mice were excreted and grown in strong magnetic fields that did not have a noticeable influence on them. Other biological experiments also did not discovery the attention of magnetic effects on biological processes.

Important to remember!

It will not be correct to assume that weak effects always pass without consequences. Such reasoning could lead to the conclusion that the severity does not have an energy value in a molecular scale, but, nevertheless, the trees on the hillside are growing vertically. The explanation seems to be in the total strength acting on the biological object, the dimensions of which are many more than the dimensions of the molecule. Indeed, a similar phenomenon ("tropism") was experimentally demonstrated in the case of seedlings growing in the presence of a very inhomogeneous magnetic field.

By the way, if you put the head into a strong magnetic field and shake it, then you will feel the "taste" of the electrolytic current in the mouth, which is proof of the presence of the induced electromotive force.

When interacting with the substance, the role of magnetic and electric fields is different. Since atoms and molecules consist of slowly moving electrical charges, electrical forces with molecular processes dominate the magnetic.

conclusions

The impact of the magnetic field of such a magnet on biological objects is not more than bite of mosquito. Any living creature or plant is constantly under the influence of earthly magnetism much stronger.

Therefore, it is not noticeable for the action of an incorrectly measured field.

Calculations

1 Gauss \u003d 1 10 -4 Tesla.

The unit of tension of the geomagnetic field (T) in the SI system is the ampere per meter (a / m). Another Ersted (E) or Gamma (D) (D), equal to 10 -5 E., was also used in the magnetic appendix. However, a practically measured magnetic field parameter is magnetic induction (or magnetic flux density). The unit of magnetic induction in the SI system is Tesla (TL). In MagnitoProduction, a smaller nanotela unit (NTL) is used, equal to 10 -9 T. Since for most media in which the magnetic field is studied (air, water, the absolute majority of non-magnetic sedimentary rocks), then the magnetic field of the Earth can be measured either in units of magnetic induction (in NTL), or in the corresponding field strength - gamma.

The figure shows the complete tension of the magnetic field of the Earth for the 1980 era of the insulance of the tons were carried out after 4 mkl (from the book P.Sharma "Geophysical Methods in Regional Geology").

In this way

On the poles, the vertical components of magnetic induction are approximately equal to 60 mkl, and horizontal - zero. At the equator, the horizontal component is approximately 30 mkl, and the vertical is zero.

In this way modern science About geomagnetism has long been abandoned from the basic principle of magnetism, two magnets located plastics to each other seek to connect with the variepete poles.

That is, judging by the last phrase at the Equator of Power (vertical component), which attracts the magnet to the ground is not! How and repulsive!

Such two magnets do not attract? That is, there is no strength of attraction, but is the power of stretching? Nonsense!

But on the poles with this location of the magnet, it is, but the horizontal force disappears.

And the difference of just 2 times, between these components!

Simply take two magnets and make sure that at a similar position the magnet first turns, and then attracts. South Pole To the North Pole!