Magnetized bar has two magnetic poles, North and South. The magnetic field of such a block is a dipole, i.e. a field with two poles ("d" means two) . The form can be seen with iron filings. The lines of force of this field are as focused sawdust. Each opielka is a compass needle. It is oriented along the magnetic field, tangent lines of force of the magnetic field.

The earth is also magnetized. It has its own magnetic field with two poles, around the globe, you can create a magnetic field if inside pole to put magnetized bar. But how? First, it should be placed along the axis of rotation of the Earth. Half of the bar in the Northern hemisphere and the other half in the South.

The South magnetic pole should be sent to the North geographic pole. Then the magnetic North pole bar would coincide with the geographic South pole.

Then the bar reject from the axis of rotation of the Earth on 11 degrees. We must reject it to its magnetic pole rested in the city of Tula (Greenland). Then the magnetic field of a bar, "tied" thus the Earth will be similar to the Earth's magnetic field.

The magnetic field of the earth's dipole is the same on all sides: day, night, morning and evening. It does not depend on the position of the Sun. Over a magnetic equator, it is held horizontally. Over the magnetic poles, the magnetic field lines of the Earth is directed vertically. It is believed that magnetic field is directed from the North magnetic pole to the South pole. Hence, the magnetic field lines of the Earth is directed in the southern hemisphere from the bottom up, and in the North - from the top down. Power lines, leaving the magnetic North pole (in the southern hemisphere), are in the South magnetic pole in the Northern hemisphere.

To avoid confusion due to the fact that the North magnetic pole is located in the southern hemisphere and the southern - in the North, agreed to name a magnetic pole in the Northern hemisphere North geomagnetic pole. Compass needle turns to the North its magnetic North pole. This is because in the North, the South magnetic pole. WE will stick to the terminology of scientists. We assume that the geomagnetic North pole is located in the Northern hemisphere (near Tula). But let us remember that there is actually a South magnetic pole. Depends on the direction of magnetic field lines.

Whether the Earth's magnetic field is the field of dipole? In principle Yes, but the details have not. These parts are nevertheless very important. They were able to establish only recently, when the spacecraft was possible to measure the magnetic field far beyond the borders of the Land. These measurements helped to establish what actually form the Earth's magnetic field in detail.

It turned out that the magnetic field of the Earth from the Sun is not the same as with the opposite (night) side.

In the area adjacent to the Earth's magnetic field is dipolar and does not depend on the situation and even the presence of the Sun. In more remote from Earth region at distances larger than three radius of the Earth, the difference in magnetic fields are very important. It consists in the following.

Magnetic dipole field is characterized "craters" on magnetic fields. The real Earth's magnetic field, these craters are not above the magnetic poles, and moved to the side of the equator, about 1000 km from the poles. In addition, the shape of the magnetic field lines on the sunlit side is very different from that on the night side. As this depends on the position of the Sun, it is the Sun "guiltily" in this distinction. How to understand the essence of this influence - the influence of the Sun on the form of the magnetic field of the Earth?

Solar wind and the magnetosphere of the Earth

How does the Sun hit the Earth's magnetic field? It is obvious that it cannot act on a magnetic field of its attraction. Can not act on magnetic field and the solar light, and x-ray, infrared and gamma radiation. The same applies to the radio waves emitted by the Sun. They should also be excluded from those factors that shape the Earth's magnetic field. What remains? Charged particles that are ejected from the Sun's atmosphere and go into space. We have already spoken about these particles. They have different energies, and thus different speeds. Charged particles with small speeds that continually come from the Sun in all countries, called the solar wind. Streams of high-energy charged particles are ejected from the solar atmosphere from time to time. They have a big speed and reach the Earth faster than the particles of the solar wind.

We can assume that the agent that defines the shape of the magnetic field of the Earth, or rather deformation of the magnetic dipole of the Earth, was found. This solar-charged particles. It remains to be seen how charged particles do. To understand this, we must remember, as charged particles interact with the magnetic field.

If a charged particle moving in a magnetic field, its movement depends on the field. The exception is only one case - when a charged particle moves strictly along the magnetic field lines. In this case, the charged particle does not feel the presence of a magnetic field, it moves as if the magnetic field does not. If a charged particle is moving across the magnetic field, the trajectory changes: instead of a straight line to entry into the field, it becomes a circle. The stronger the magnetic field, the smaller the circle (at the same particles) . But on the other hand, the more energy is flying particles, the harder the magnetic field to bend its trajectory in a small circle.

There is some balance. To change the trajectory of a charged particle with a certain energy, magnetic field must have a certain value and be directed perpendicular to the motion of particles. If this condition is met, charged particles begin to revolve around power lines. Speed and radii of the circles in which they revolve, depend on the magnitude of the magnetic field and energy of particles. Positively charged particles rotate in one direction, and negatively charged to the opposite direction. Solar charged particles coming to the Earth's magnetic field at different angles: and longitudinally, and perpendicular and oblique. Those particles that fit along the lines of force (above the magnetic poles)should easily get in magnetic shells of the Earth (magnetosphere) . The particles that come to power lines perpendicular, deep into the magnetosphere will not pass. Their trajectories curl around the magnetic field lines. What will be the particles that obliquely fall on the magnetic field? It is especially important to know that these particles are the majority.

When a charged particle moves at a certain angle (but not direct) to the magnetic field lines, it is its motion can be decomposed into two: along the field and across it. Actually, in this case, we velocity vector particles spread on components along the magnetic field and across it. The motion of this particle in a magnetic field will become a spiral movement. Particle will revolve around power lines and at the same time to move along power lines. The trajectory of the particle will be in the form of a spiral.

The radius of the spiral and her step will be unchanged if will remain constant energy particles and the form and intensity of the magnetic field. This means that the magnetic field lines are straight, the distance between which is always in the direction of motion of the particle. This condition of homogeneity of the magnetic field. But this case of a homogeneous magnetic field for us little interesting. Because the Earth's magnetic field is not homogenous. As in this case will move particles?

If the magnetic field lines converge, that is, a particle moving in a spiral moving in an increasingly strong magnetic field, its promotion in this field is gradually slowed down. Magnetic field prevents the promotion of particles. It allows unobstructed particle inside only in case if it moves strictly along the magnetic field lines. Spiraling towards a stronger magnetic field, charged particle at some distance stops to go. After that it gradually (also spiral) is moving in the opposite direction. Magnetic field pushes a charged particle in a more weak fields.

The Earth's magnetic field is not homogenous. This is evident in the form of lines of force. As you move from the equator to the poles along the lines of force shows that they are gathering more and more. This means that the magnetic field increases. In this magnetic field, which is increasing in both directions from the equator, a charged particle is caught, trapped. Revolving on spirals, charged particles moving in this field consistently reflected from a stronger field alternately in the South, in the Northern hemisphere. When charged particles are above the earth's atmosphere. These charged particles were actually measured in the magnetosphere of the Earth. They were called radiation belts.

As deformed the Earth's magnetic field of the solar particles? Because charged particles interact with the magnetic field, they can this field be deformed. The stream of charged particles, flying from the Sun interacts with the external power lines of the Earth's magnetosphere. The ends of the lines of force remain in the same place, in the Land. And the line "turn inside" and an extractyaytsa stream of charged particles on the night side. They cover of the magnetic pole, and funnel over the poles disappear. But the formation of new crater on the Meridian Meridian. New funnel removed from the poles about 1000 km.

It is very important that these craters can be displaced. The more energy the solar flux of charged particles, the more power lines he turns from the day side to the night. The more funnel is removed from the pole.

Under the action of solar charged particles with daylight side of the magnetosphere of the Earth is limited to a certain distance from the surface of the Earth. When the Sun is calm, the distance is approximately ten earth radii. During solar storms flux of solar particles increases and pressed the magnetosphere on the Sunny side closer to the Ground. At this time, funnel moving further from the pole. With a very strong solar storms magnetosphere on the sunlit side can be compressed to three earth radii. Then funnel shift from the pole.

Under the action of solar charged particles is changing not only the position of craters that the dipole located above the poles.

Funnel not only shifted towards the equator. They change their shape. Each funnel when this turns into splyusnutoy funnel-a crack in the form of a horseshoe. It covers a specific area on the sunlit side of the magnetosphere.

Night part of the magnetosphere little similar to the day. If on the daylight side of the Earth's magnetic field extends up to a distance of ten of the earth radii, on the night side is at a great distance, equal to one hundred times the radius of the Earth, and more. The magnetic field lines of the Earth are stretched in the direction of solar particles, that is from the Earth. Thus, there is a train lines of force of the Earth's magnetosphere. Experts called the tail of the magnetosphere.

Charged particles move freely along the magnetic field lines. This means that solar charged particles through a funnel on the sunlit side can penetrate through the magnetosphere of the Earth and its atmosphere. But inside the magnetosphere are charged particles, which are captured there. In the magnetotail there are also charged particles. From here they are moving along the magnetic field lines. Where will they go? You can see what they will get in the Arctic and Antarctic.

If you monitor by charged particles on day and night sides of the magnetosphere, one will find that they come just at the ring (oval) , which is illuminated by the Aurora. Is it surprising?