The magnetosphere envelops any body with a magnetic field. It appears due to the fact that particles with charges deviate from the original line of motion under the influence of internal magnetism. The meeting point of solar energy and magnetic field forms a plasma covering the magnetospheric shell.
Influence of the Sun on the Earth
The sun releases a large amount of energy, which is constantly expanding, "evaporates" outside. This extension is called the solar wind.
The solar wind spreads in any direction, filling the entire interplanetary space. For this reason, a plasma formation called the solar wind plasma forms in the interstellar region.
The solar plasma moves in a spiral, over an average of 4 days it overcomes the interval between the Sun and the Earth.
The sun releases energy through which life on Earth continues. However, dangerous radiation is also emanating from the Sun, which is destructive for all living things on our planet. When the Earth moves around the Sun, radiation is distributed unevenly throughout the year. For this reason, the seasons are changing.
What protects the earth?
The natural structure of planet Earth protects it from harmful solar radiation. The earth is surrounded by several shells:
- a magnetosphere that protects against radiation from the solar flux;
- ionosphere absorbing x-ray and ultraviolet radiation;
- the ozone layer, restraining residual amounts of ultraviolet radiation.
As a result, the biosphere of the Earth (the living environment of living organisms) is completely protected.
The Earth’s magnetosphere is the protective layer farthest from the center of the planet. It is a barrier to the plasma of the solar wind. For this reason, the plasma of the Sun flows around the Earth, forming a cavity formation in which a geomagnetic field is hidden .
Why is there a magnetic field?
The causes of terrestrial magnetism are hidden within the planet. As you know about the structure of planet Earth, it consists of:
- kernels;
- mantles;
- Earth's crust.
Around the planet there are various fields, including gravitational and magnetic. Gravity in the simplest sense is the attraction of the earth for all material particles.
Earthly magnetism consists in the phenomena occurring at the boundaries of the core and mantle. The planet itself is a huge magnet, a uniformly magnetized ball.
The cause of any magnetic field is an electric current or continuous magnetization. Scientists involved in the problem of magnetism of the Earth, find out:
- causes of the Earth's magnetic attraction;
- establish connections between terrestrial magnetism and its sources;
- determine the distribution and orientation of the magnetic field on the planet.
These studies are carried out through magnetic surveys, as well as through observations at observatories - special points in different areas of the globe.
How is the magnetosphere arranged?
The type and structure of the magnetosphere are produced:
- solar wind;
- earthly magnetism.
The solar wind is the exit of plasma, distributed from the Sun in any direction. The wind speed at the earth's surface is 300-800 km / s. The solar wind is filled with protons, electrons, alpha particles and is characterized by quasineutrality. The solar wind is endowed with solar magnetism, moved by plasma very far.
The Earth’s magnetosphere is a rather complicated cavity. All its parts are filled with plasma processes, in which the mechanisms of particle acceleration are of great importance. On the sunny side, the gap from the center to the boundaries of the Earth is determined by the strength of the solar wind and can reach from 60 to 70 thousand kilometers, which is equal to 10-12 Earth radii Re. Re is 6371 km.
The boundaries of the magnetosphere are different depending on the location relative to the Sun. A similar border on the sunny side is similar in shape to a shell. Its approximate distance is 15 Re. On the dark side, the magnetosphere takes the form of a cylindrical tail, its radius is 20-25 Re, its length is more than 200 Re, the end is unknown.
In the magnetosphere there are areas with high energy particles, they are called "radiation belts." The magnetosphere is capable of initiating various vibrations and is itself a source of radiation, part of which can penetrate the Earth.
Plasma seeps into the Earth’s magnetosphere at intervals between the magnetopause features — the polar cusps, as well as due to hydromagnetic phenomena and instabilities.
Magnetic field activity
The Earth’s magnetosphere affects geomagnetic activity, geomagnetic storms and substorms.
She protects life on Earth. Without her, life would have ceased. According to scientists, the oceans of Mars and its atmosphere went into space due to the undisguised influence of the solar wind. Similarly, the waters of Venus were carried into outer space by a solar stream.
Jupiter, Uranus, Saturn and Neptune also have a magnetosphere. In Mars and Mercury, the magnetic shells are insignificant. Venus does not have it at all, it is possible to cope with the solar wind thanks to the ionosphere.
Field Features
The main property of a magnetic field is intensity. Magnetic tension is a vector quantity. The magnetic field of the planet is depicted using force lines, tangents to them show the direction of the tension vector.
The magnetic field today is 0.5 Oersted or 0.1 a / m. Scientists allow fluctuations in the past. But the last 2-3.5 billion years, the geomagnetic field has not changed.
Points on Earth where tension is vertically directed are called magnetic poles. There are two of them on Earth:
A straight line passes through both poles - the magnetic axis. A circle perpendicular to the axis is the magnetic equator. The field strength at the equator is horizontal.
Magnetic poles
Magnetic poles do not correspond to usual geographical ones. Geographic poles are placed along the geographic axis along which the planet rotates. When the earth moves around the sun, the direction of the earth's axis is preserved.
The compass needle points precisely to the magnetic north pole. Magnetic observatories measure the fluctuations of the magnetic field during the day, some of them are engaged in every second measurement.
Magnetic meridians pass from the North Pole to the South. The angle between the magnetic and geographical meridian is called magnetic declination. Any point on earth has its own declination angle.
At the equator, the magnet arrow is placed horizontally. When moving north, the upper end of the arrow rushes down. The angle between the arrow and the horizontal surface is the magnetic inclination. In the field of poles, the inclination is the largest and is 90 degrees.
Magnetic field movement
Over time, the location of the magnetic poles changes.
Initially, the magnetic pole was discovered in 1831, and then it was located hundreds of kilometers from its current location. Approximate travel distance per year is 15 km.
In recent years, the rate of movement of magnetic poles has been increasing. The North Pole moves at a speed of 40 km per year.
Permutation of magnetic fields
The process of changing polarities on Earth is called inversion. Scientists know at least 100 cases when the geomagnetic field reversed its polarity.
It is believed that inversion occurs once every 11-12 thousand years. Other versions are called 13, 500 and even 780 thousand years. Perhaps the inversion does not have a clear periodicity. Scientists believe that with previous inversions, life on Earth was preserved.
People ask themselves: “When to wait for the next polarity reversal?”
The pole shift has been going on over the past century. The South Pole is now located in the Indian Ocean, and the North is shifting through the Arctic Ocean towards Siberia. In this case, the magnetic field near the poles weakens. Tension is reduced.
Most likely, with the next inversion, life on Earth will continue. The question is, at what cost. If the inversion occurs with the extinction of the magnetosphere on Earth for a short time, it can be very dangerous for humanity. An unprotected planet is adversely affected by cosmic rays. In addition, a decrease in the ozone layer can also be a serious hazard.
The pole change in the Sun, which occurred in 2001, did not lead to the disconnection of its magnetic layer. Whether such a scenario will be on Earth, scientists do not know.
Earth magnetosphere perturbation: human impact
At the initial approximation, the solar plasma does not reach the magnetosphere. But under certain conditions, the permeability of the plasma is violated, damage to the magnetic shell occurs. The solar plasma and its energy penetrate the magnetosphere. With respect to the rate of arrival of energy flows, there are three possible responses of the magnetosphere:
- Calm state of the magnetosphere — the shell does not change its state, since the speed of energy transfer is too low or equal to the amount of scattered energy inside the magnetic sphere.
- Magnetic substorm. A state that occurs when the rate of incoming energy is higher than the rate of stationary dissipation, and part of the energy escapes from the magnetosphere through a channel called a substorm. The process consists in the release of part of the magnetospheric energy. His most striking embodiment is the aurora. Emissions of excess energy can occur with a frequency of 3 hours in the polar regions of both hemispheres.
- A magnetic storm is a process of severe field disturbance due to the high speed of incoming energy from outside. The magnetic field also undergoes changes below, in the equator.
The Earth’s magnetic field changes locally during substorms, and global changes during storms. In any case, these changes do not exceed a few percent, which is much smaller than the technogenic fields.
Medicine believes that magnetic storms adversely affect human health. During this period, the number of patients suffering from cardiovascular pathologies, depression and other neuropsychiatric disorders increases.
The role of the Earth’s magnetosphere in all geographical processes on the planet is great. This protective shell protects our planet from many adverse processes and has an impact on weather conditions. Under the influence of changes in the magnetosphere on Earth, climatic features, forms of vital activity of animals and plants, and much more are changing.