Venus is very similar to Earth in some characteristics. However, these two planets also have significant differences due to the peculiarities of the formation and evolution of each of them, and scientists are identifying more and more such features. We will look here in more detail at one of the distinguishing features - special character magnetic field Venus, but first let's look at general characteristics planet and some hypotheses affecting issues of its evolution.
Venus in the Solar System
Venus is the second planet closest to the Sun, a neighbor of Mercury and Earth. Relative to our star, it moves in an almost circular orbit (the eccentricity of the Venusian orbit is less than that of the Earth) at an average distance of 108.2 million km. It should be noted that eccentricity is a variable quantity, and in the distant past it could have been different due to the gravitational interactions of the planet with other bodies of the Solar System.
There are no natural ones. There are hypotheses according to which the planet once had a large satellite, which was subsequently destroyed by tidal forces or lost.
Some scientists believe that Venus experienced a tangential collision with Mercury, as a result of which the latter was thrown into a lower orbit. Venus changed the nature of its rotation. It is known that the planet rotates extremely slowly (as does Mercury, by the way) - with a period of about 243 Earth days. In addition, the direction of its rotation is opposite to that of other planets. We can say that it rotates, as if turned upside down.
Main physical features of Venus
Along with Mars, Earth and Mercury, Venus is a relatively small rocky body of predominantly silicate composition. It is similar to the Earth in terms of 94.9% of the Earth's) and mass (81.5% of the Earth's). The escape velocity on the planet's surface is 10.36 km/s (on Earth - approximately 11.19 km/s).
Of all the terrestrial planets, Venus has the densest atmosphere. The surface pressure exceeds 90 atmospheres, average temperature about 470 °C.
To the question whether Venus has a magnetic field, there is the following answer: the planet has practically no field of its own, but due to the interaction of the solar wind with the atmosphere, a “false” induced field appears.
A little about the geology of Venus
The vast majority of the planet's surface is formed by products of basaltic volcanism and is a collection of lava fields, stratovolcanoes, shield volcanoes and other volcanic structures. Impact craters few have been discovered, and from a count of their numbers it has been concluded that they cannot be older than half a billion years. Signs of plate tectonics are not visible on the planet.
On Earth, plate tectonics, together with mantle convection processes, serves as the main mechanism for heat transfer, but this requires a sufficient amount of water. Presumably, on Venus, due to a lack of water, plate tectonics either stopped for another early stage, or did not take place at all. So get rid of the excess internal heat the planet could only be through a global supply of superheated mantle matter to the surface, possibly with complete destruction of the crust.
Just such an event could have taken place about 500 million years ago. It is possible that in the history of Venus it was not the only one.
The core and magnetic field of Venus
On Earth, the global is generated due to the dynamo effect created by the special structure of the core. The outer layer of the core is molten and is characterized by the presence of convective currents, which, together with the rapid rotation of the Earth, create a fairly powerful magnetic field. In addition, convection promotes active heat transfer from the internal solid core, which contains many heavy, including radioactive elements, the main source of heating.
Apparently, on our planet's neighbor, this entire mechanism does not work due to the lack of convection in the liquid outer core - which is why Venus does not have a magnetic field.
Why are Venus and Earth so different?
The reasons for the serious structural differences between two planets with similar physical characteristics are not yet entirely clear. According to one of the recently constructed models, the internal structure of rocky planets is formed layer by layer as mass increases, and the rigid stratification of the core prevents convection. On Earth, the multilayer core was presumably destroyed at the dawn of its history as a result of a collision with a sufficiently large object- Teyei. In addition, the result of this collision is considered to be the creation of the Moon. Tidal influence of a large satellite on earth's mantle and the core can also play a significant role in convective processes.
Another hypothesis suggests that Venus initially had a magnetic field, but the planet lost it due to a tectonic catastrophe or a series of catastrophes, discussed above. In addition, many researchers blame the absence of a magnetic field on the too slow rotation of Venus and the low precession of the rotation axis.
Features of the Venusian atmosphere
Venus has an extremely dense atmosphere, consisting mainly of carbon dioxide with a small admixture of nitrogen, sulfur dioxide, argon and some other gases. Such an atmosphere serves as a source of an irreversible greenhouse effect, preventing the surface of the planet from cooling to any extent. Perhaps due to the state of the atmosphere " morning star“The above-described “catastrophic” tectonic regime of its subsoil is also responsible.
Largest part The gaseous shell of Venus is contained in the lower layer - the troposphere, extending to altitudes of about 50 km. Above is the tropopause, and above it is the mesosphere. Upper limit clouds consisting of sulfur dioxide and drops of sulfuric acid are located at an altitude of 60-70 km.
In the upper layers of the atmosphere, the gas is highly ionized by solar ultraviolet radiation. This layer of rarefied plasma is called the ionosphere. On Venus it is located at altitudes of 120-250 km.
Induced magnetosphere
It is the interaction of charged particles from the solar wind and the plasma of the upper atmosphere that determines whether Venus has a magnetic field. The magnetic field lines carried by the solar wind bend around the Venusian ionosphere and form a structure called the induced magnetosphere.
This structure has the following elements:
- A bow shock wave located at a height of approximately one third of the radius of the planet. At the peak of solar activity, the area where the solar wind meets the ionized layer of the atmosphere significantly approaches the surface of Venus.
- Magnetic layer.
- The magnetopause is the actual boundary of the magnetosphere, located at an altitude of about 300 km.
- The tail of the magnetosphere, where the stretched magnetic field lines of the solar wind are straightened. The length of the magnetospheric tail of Venus ranges from one to several tens of planet radii.
The tail is characterized by special activity - magnetic reconnection processes leading to the acceleration of charged particles. In the polar regions, as a result of reconnection, magnetic ropes similar to those on Earth can be formed. On our planet, the reconnection of magnetic lines of force underlies the phenomenon of auroras.
That is, Venus has a magnetic field that is not formed internal processes in the bowels of the planet, but by the influence of the Sun on the atmosphere. This field is very weak - its intensity is on average a thousand times weaker than that of geomagnetic field Earth, however, it plays a certain role in the processes occurring in the upper atmosphere.
Magnetosphere and stability of the gas shell of the planet
The magnetosphere shields the planet's surface from the effects of energetic charged particles from the solar wind. It is believed that the presence of a sufficiently powerful magnetosphere made possible occurrence and the development of life on Earth. In addition, the magnetic barrier to some extent prevents the atmosphere from being “blown away” by the solar wind.
Ionizing ultraviolet radiation, which is not blocked by the magnetic field, also penetrates into the atmosphere. On the one hand, due to this, the ionosphere arises and a magnetic screen is formed. But ionized atoms can leave the atmosphere, entering the magnetic tail and accelerating there. This phenomenon is called ion runaway. If the speed acquired by the ions exceeds the escape speed, the planet intensively loses gas shell. This phenomenon is observed on Mars, which is characterized by weak gravity and, accordingly, low escape velocity.
Venus, with its more powerful gravity, is more effective at trapping ions in its atmosphere, since they need to gain greater speed to leave the planet. The induced magnetic field of the planet Venus is not powerful enough to significantly accelerate the ions. Therefore, the loss of atmosphere here is not nearly as significant as on Mars, despite the fact that the intensity of ultraviolet radiation is much higher due to its proximity to the Sun.
So the induced magnetic field of Venus is one example complex interaction upper atmosphere from various types solar radiation. Together with gravitational field it is a factor in the stability of the gaseous shell of the planet.
Presence or absence of planets magnetic field associated with their internal structure. All terrestrial planets have their own magnetic field. The giant planets and Earth have the strongest magnetic fields. The source of a planet's dipole magnetic field is often considered to be its molten conductive core. Venus and Earth have similar sizes, average density, and even internal structure However, the Earth has a fairly strong magnetic field, but Venus does not (the magnetic moment of Venus does not exceed 5-10% of the Earth's magnetic field). According to one of the modern theories, the strength of the dipole magnetic field depends on the precession of the polar axis and the angular velocity of rotation. It is these parameters that are negligibly small on Venus, but measurements indicate even lower tension than theory predicts. Current assumptions about Venus' weak magnetic field are that there are no convective currents in Venus' supposedly iron core.
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An excerpt characterizing the magnetic field of planets
Natasha threw off the scarf that was draped over her, ran ahead of her uncle and, putting her hands on her hips, made a movement with her shoulders and stood.Where, how, when did this countess, raised by a French emigrant, suck into herself from that Russian air that she breathed, this spirit, where did she get these techniques that pas de chale should have long ago been supplanted? But these spirits and techniques were the same, inimitable, unstudied, Russian ones that her uncle expected from her. As soon as she stood up and smiled solemnly, proudly and slyly with gaiety, the first fear that gripped Nikolai and everyone present, the fear that she would do the wrong thing, passed and they were already admiring her.
She did the same thing and did it so precisely, so completely accurately that Anisya Fedorovna, who immediately handed her the scarf she needed for her business, burst into tears through laughter, looking at this thin, graceful, so alien to her, well-bred countess in silk and velvet. , who knew how to understand everything that was in Anisya, and in Anisya’s father, and in her aunt, and in her mother, and in every Russian person.
“Well, the countess is a pure march,” the uncle said, laughing joyfully, having finished the dance. - Oh yes niece! If only you could choose a good guy for your hubby, it’s pure business!
“It’s already been chosen,” Nikolai said, smiling.
- ABOUT? - the uncle said in surprise, looking questioningly at Natasha. Natasha nodded her head affirmatively with a happy smile.
- What a great one! - she said. But as soon as she said this, another new system thoughts and feelings rose within her. What did Nikolai’s smile mean when he said: “already chosen”? Is he happy about this or not? He seems to think that my Bolkonsky would not approve, would not understand this joy of ours. No, he would understand everything. Where is he now? Natasha thought and her face suddenly became serious. But this only lasted for one second. “Don’t think, don’t dare think about it,” she said to herself and, smiling, sat down next to her uncle again, asking him to play something else.
Abstract research work
Magnetic field of planets solar system
Completed:
Balyuk Ilya
Supervisor:
Levykina R.H.
Physics teacher
Magnitogorsk 2017 G
Anotation.
One of specific features our planet is its magnetic field. All living creatures on Earth have evolved for millions of years precisely under the conditions of a magnetic field and cannot exist without it.
this work made it possible to expand my knowledge about the nature of the magnetic field, its properties, about the planets of the Solar System that have magnetic fields, about hypotheses and astrophysical theories of the origin of the magnetic fields of the planets of the Solar System.
Content
Introduction…………………………………………………………………………………..4
Section 1. Nature and features of the magnetic field…………………………..6
1.1,Definition of the magnetic field and its characteristics. …………………...
1.2.Graphic representation of the magnetic field……………………………
1.3.Physical properties of magnetic fields………………………………….
Section 2. Earth's magnetic field and related matters natural phenomena…. 9
Section 3. Hypotheses and astrophysical theories of the origin of the magnetic field of planets……………………………………………………………………………………………… 13
Section 4. Review of planets of the solar system with magnetic
field………………………………………………………………………………………...16
Section 5. The role of the magnetic field in existence and development
life on Earth………………………………………………………………………………….. 20
Conclusion………………………………………………………………………. 22
Used Books………………………………………………………. 24
Application………………………………………………………………………. 25
Introduction
The Earth's magnetic field is one of the necessary conditions for the existence of life on our planet. But geophysicists (paleomagnetologists) have established that throughout geological history Our planet’s magnetic field has repeatedly reduced its intensity and even changed sign (that is, the north and south poles have swapped places). Several dozen such epochs of changing the sign of the magnetic field, or inversions, have now been established; they are reflected in magnetic properties ah magnetic rocks. The current era of the magnetic field is conventionally called the era of direct polarity. It has been going on for about 700 thousand years. However, the field strength is slowly but steadily decreasing. If this process continues to develop, then in approximately 2 thousand years the strength of the Earth’s magnetic field will drop to zero, and then, after certain time"without a magnetic epoch", will begin to increase, but will have opposite sign. “Without a magnetic era” can be perceived by living organisms as a catastrophe. The Earth's magnetic field is a shield that protects life on Earth from the flow of solar and cosmic particles(electrons, protons, nuclei of some elements). Moving with enormous speeds, such particles are strong ionizing factor, which is known to affect living tissue, and, in particular, on the genetic apparatus of organisms. It has been established that the earth's magnetic field deflects the trajectories of cosmic ionizing particles and “spins” them around the planet.
Scientists have identified the main astronomical characteristics of the planets. These include: Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
In our opinion, one of the leading characteristics of planets is the magnetic field
Relevance Our research is to clarify the characteristics of the magnetic field of a number of planets in the solar system.
TheNewYorkTimes.
expansion of ozone holes, and northern lights will appear above the equator.
Problem The research is to resolve the contradiction between the need to take into account the magnetic field as one of the characteristics of the planets, and the lack of taking into account data indicating the relationship between the magnetic field of the Earth and other planets of the solar system.
Target systematize data on the magnetic field of the planets of the solar system.
Tasks.
1. Explore current state magnetic field problems in scientific literature.
2. Clarify the presenters physical characteristics magnetic field of planets.
3. Analyze hypotheses of the origin of the magnetic field of the planets of the Solar System, establish which of them are accepted by the scientific community.
4 . Supplement the generally accepted table of “Main astronomical characteristics planets” data on the magnetic fields of the planets.
An object: basic astronomical characteristics of the planets.
Item : identifying the features of the Magnetic field as one of the main astronomical characteristics of the planets.
Research methods: analysis, synthesis, generalization, systematization of meanings.
Section 1. Magnetic field
1.1. It has been experimentally established that conductors through which currents flow in the samedirections attract, and in opposite directions they repel. To describe the interaction of wires through which currents flow, it was useda magnetic field- a special form of matter generated by electric currents or alternating electric current and manifested by its effect on existing electric currentsin this field. The magnetic field was discovered in 1820 by the Danish physicist H.C. Oersted. A magnetic fielddescribes magnetic interactions that arise: a) between two currents; b) between current and moving charges; c) between two moving charges.
The magnetic field is directional and should be characterized vector quantity.. The main force characteristic of the magnetic field was namedm magneticby induction.This value is usually denoted by the letter B.
Rice. 1
When connecting the ends of the wire to the source direct current the arrow “turned away” from the wire. Several magnetic needles placed around the wire turned in a certain way.
In the space aroundwires carrying current there is a force field. In the space around a conductor carrying currentexistsa magnetic field. (Fig.1)
To characterize the magnetic field of the current, in addition to induction, an auxiliary quantity was introducedN , called the magnetic field strength. The magnetic field strength, unlike magnetic induction, does not depend on the magnetic properties of the medium.
Rice. 2
Magnetic needles placed at the same distance from a straight conductor with current are arranged in the form of a circle.
1.2 Magnetic field induction lines.
Magnetic fields, like electric ones, can be represented graphically using magnetic induction lines.Induction lines (or lines of vector B) are lines whose tangents are directed in the same way as vector B at a given point in the field. Obviously,that through each point of the magnetic field an induction line can be drawn. Since the field induction at any point has a certain direction, then the direction of the lineinduction at each point of a given field can only be unique, which means that the linemagnetic field inductiondrawn with such density that the number of lines intersecting a unit of surfaceperpendicular to them, was equal to (or proportional to) the magnetic field induction in a given location. Therefore, by depicting the induction lines, we can clearly imagine howthe induction changes in space in modulus and direction.
1.3. Vortex nature of the magnetic field.
Magnetic induction linescontinuous: they have neither beginning nor end. It hasplace for any magnetic field caused by any current circuits. Vector fields having continuous lines are calledvortex fields. We see that the magnetic field is a vortex field.
Rice. 3
Small iron filings are arranged in the form of circles, “encircling” the conductor. If you change the polarity of connecting the current source, the sawdust will turn 180 degrees.
Rice. 4
The magnetic field of a circular current consists of closed continuous lines the following type: (Fig. 5, 7)
Rice. 5
For a magnetic field, as for an electric field,fairsuperposition principle: field B generated by several moving charges (currents) is equal to the vector sum of fields W,generated by each charge (current) separately: i.e., to find the force acting on a point in space, you need to add the forces,acting on it, as shown in Figure 4.
M magnetic field of circular current represents a kind of figure eight with divisionrings in the center of the ring through which current flows. Its diagram is shown in the figure below: (Fig. 6)
Rice. 6 Fig. 7
Thus: a magnetic field is a special form of matter through which interaction occurs between moving electrically charged particles.
ABOUT main magnetic field properties:
1.
2.
M The magnetic field is characterized by:
A) b)
Graphically, the magnetic field is represented using magnetic induction lines
Section 2. The Earth's magnetic field and related natural phenomena
The Earth as a whole is a huge spherical magnet. Humanity began to use the Earth's magnetic field a long time ago. Already at the beginningXII- XIIIcenturies receives wide use in navigation, compass. However, in those days it was believed that the compass needle was oriented polar Star and its magnetism. The English scientist William Gilbert, court physician to Queen Elizabeth, was the first to show in 1600 that the Earth is a magnet, the axis of which does not coincide with the axis of rotation of the Earth. Consequently, around the Earth, like around any magnet, there is a magnetic field. In 1635, Gellibrand discovered that the earth's magnetic field is slowly changing, and Edmond Halley conducted the world's first magnetic survey of the oceans and created the first world maps (1702). In 1835, Gauss conducted a spherical harmonic analysis of the Earth's magnetic field. He created the world's first magnetic observatory in Göttingen.
2.1 General characteristics of the Earth's magnetic field
At any point in the space surrounding the Earth and on its surface, the action of magnetic forces is detected. In other words, a magnetic field is created in the space surrounding the Earth.The Earth's magnetic and geographic poles do not coincide with each other. The north magnetic pole N lies in the southern hemisphere, near the coast of Antarctica, and the south magnetic poleSlocated in the Northern Hemisphere, near northern shore Victoria Islands (Canada). Both poles continuously move (drift) on earth's surface at a speed of about 5 0 per year due to the variability of the processes generating the magnetic field. In addition, the axis of the magnetic field does not pass through the center of the Earth, but lags behind it by 430 km. The Earth's magnetic field is not symmetrical. Due to the fact that the axis of the magnetic field passes at an angle of only 11.5 0 to the axis of rotation of the planet, we can use a compass.
Fig 8
In an ideal and hypothetical assumption in which the Earth would be alone in outer space, the field lines of the planet's magnetic field were located in the same way as the field lines of a conventional magnet from school textbook physics, i.e. in the form of symmetrical arcs stretching from south pole to the north. (Fig. 8) The line density (magnetic field strength) would fall with distance from the planet. In fact, the Earth's magnetic field interacts with the magnetic fields of the Sun, the planets, and the streams of charged particles emitted in abundance by the Sun. (Figure 9)
Fig 9
If the influence of the Sun itself, and especially the planets, can be neglected due to their distance, then this cannot be done with particle flows, otherwise the solar wind. The solar wind is a stream of particles rushing at a speed of about 500 km/s emitted by sunny atmosphere. At moments of solar flares, as well as during periods of formation of a group of large sunspots on the Sun, the number of free electrons that bombard the Earth's atmosphere increases sharply. This leads to a disturbance in the currents flowing in the Earth's ionosphere and, due to this, a change in the Earth's magnetic field occurs. arise magnetic storms. Such flows generate a strong magnetic field, which interacts with the Earth's field, greatly deforming it. Thanks to its magnetic field. The Earth retains captured solar wind particles in so-called radiation belts, preventing them from passing into the Earth's atmosphere, much less to the surface. Solar wind particles would be very harmful to all living things. When the mentioned fields interact, a boundary is formed, on one side of which there is a disturbed one (which has undergone changes due to external influences) the magnetic field of solar wind particles, on the other - the disturbed field of the Earth. This boundary should be considered as the limit of near-Earth space, the boundary of the magnetosphere and atmosphere. Beyond this boundary, the influence of external magnetic fields predominates. In the direction of the Sun, the Earth's magnetosphere is flattened under the influence of the solar wind and extends to only 10 radii of the planet. In the opposite direction, there is an elongation of up to 1000 Earth radii.
WITH leaving the Earth's geomagnetic field.
Earth's own magnetic field(geomagnetic field) can be divided into the following three main parts.
ABOUT the Earth's main magnetic field, which experiences slow changes over time (secular variations) with periods of 10 to 10,000 years, concentrated in intervals10-20, 60-100, 600-1200 and 8000 years. The latter is associated with a change in the dipole magnetic moment by 1.5-2 times.
M global anomalies - deviations from the equivalent dipole up to 20% intensityindividual areas with characteristic dimensions of up to 10,000 km. These anomalous fieldsexperience secular variations, leading to changes over time over many years and centuries. Examples of anomalies: Brazilian, Canadian, Siberian, Kursk. During secular variations, world anomalies shift, disintegrate andarise again. At low latitudes there is a westerly drift in longitude at a speed0.2° per year.
M magnetic fields of local areas of outer shells with an extension fromseveral to hundreds of km. They are caused by magnetization rocks V top layer Lands that make up the earth's crust and are located close to the surface. One ofthe most powerful - Kursk magnetic anomaly.
P The Earth's variable magnetic field (also called external) is determined bysources in the form of current systems located beyond the earth's surface andin its atmosphere. The main sources of such fields and their changes are corpuscular flows of magnetized plasma coming from the Sun along with the solar wind, and forming the structure and shape of the Earth's magnetosphere.
Therefore: The Earth as a whole is a huge spherical magnet.
At any point in the space surrounding the Earth and on its surface, the action of magnetic forces is detected. North magnetic poleNS. is located in the Northern Hemisphere, near the northern coast of Victoria Island (Canada). Both poles continuously move (act) on the earth's surface.
In addition, the axis of the magnetic field does not pass through the center of the Earth, but lags behind it by 430 km. The Earth's magnetic field is not symmetrical. Due to the fact that the axis of the magnetic field passes at an angle of only 11.5 degrees to the axis of rotation of the planet, we can use a compass.
Section 3. Hypotheses and astrophysical theories of the origin of the Earth's magnetic field
Hypothesis 1.
M hydromagnetic dynamo mechanism
The observed properties of the Earth's magnetic field are consistent with the idea that it arises due to the mechanismhydromagnetic dynamo. In this process, the original magnetic field is intensified inthe result of movements (usually convective or turbulent) of electrically conductive matter in the liquid core of the planet. At a substance temperature ofseveral thousand kelvin its conductivity is high enough to allow convective movements,occurring even in a weakly magnetized environment, could excite changing electric currents capable, in accordance with the laws electromagnetic induction, create new magnetic fields. The attenuation of these fields either creates thermal energy (according to Joule’s law), or leads to the emergence of new magnetic fields. INDepending on the nature of the movements, these fields can either weaken or strengthen the original fields. To enhance the field, a certain asymmetry of movements is sufficient.Thus, a necessary condition hydromagnetic dynamo is the very presencemovements in a conducting medium, and sufficient is the presence of a certain asymmetry (spirality) of the internal flows of the medium. When these conditions are met, the amplification process continues until the losses by increasing with increasing current strengthJoule heat will not balance the influx of energy coming fromaccount of hydrodynamic movements.
Dynamo effect - self-excitation and maintenance in a stationary statemagnetic fields due to the movement of a conducting fluid or gas plasma. Histhe mechanism is similar to the generation of electric current and magnetic field in a dynamowith self-excitation. The dynamo effect is associated with the origin of its ownmagnetic fields of the Sun, Earth and planets, as well as their local fields, for example, fieldsspots and active areas.
Hypothesis 2.
IN rotating hydrosphere as possible source Earth's magnetic field.
Proponents of this hypothesis suggest that the problem of the origin of the Earth's magnetic field, with all itsthe above features, could find its solution based on a singlemodel that clarifies how the source of terrestrial magnetism is related tohydrosphere. This connection, they believe, is evidenced by many facts. First of all, the “skew” of the magnetic axis mentioned above is that it is tilted andshifted to the side Pacific Ocean; Moreover, it is located almost symmetrically with respect to the waters of the World Ocean.Everything suggests thatherself sea water, being in motion, generates a magnetic field.It should be said that this concept is consistent with data from paleomagnetic studies, which are interpreted as evidence of repeated switching of magnetic poles.
The decrease in the magnetic field is due to the activities of civilization, which leads to global acidification environment mainly through the accumulation of carbon dioxide in it. Such activities of civilization, taking into account the above, may turn out to be suicidal for it.
Hypothesis 3
Z Earth as a self-excited DC motor
Sun
Rice. 10Scheme of interaction between the Sun and Earth:
(-) - flow of charged particles;
1s - solar current;
1з - circular current Earth;
Mv - the moment of rotation of the Earth;
co is the angular velocity of the Earth;
Fz - magnetic flux created by the Earth's field;
Fs - magnetic flux, current generated solar wind.
Relative to the Earth, the solar wind is a stream of charged particles in a constant direction, and this is nothing more than an electric current. According to the definition of the direction of the current, it is directed towards opposite movement negatively charged particles, i.e. from Earth to Sun.
Let us consider the interaction of the solar current with the excited magnetic field of the earth. As a result of the interaction, a torque M acts on the Earth 3 , directed towards the rotation of the Earth. Thus, the Earth, relative to the solar wind, behaves similarly to a self-excited DC motor. Energy source (generator) in in this case is the Sun.
The Earth's current layer largely determines the occurrence of electrical processes in the atmosphere (thunderstorms, auroras, St. Elmo's fires). It has been noticed that during volcanic eruptions, electrical processes in the atmosphere are significantly activated.
From the above it follows: the source of the Earth’s magnetic field has not yet been established by science, which deals only with an abundance of hypotheses put forward in this regard.
The hypothesis, first of all, must explain the origin of the component of the Earth's magnetic field, due to which the planet behaves like permanent magnet with the north magnetic pole near the south geographic pole and vice versa.
Today the hypothesis about vortex electric currents, flowing in the outer part of the Earth's core, which exhibits some liquid properties. It is calculated that the zone in which the “dynamo” mechanism operates is located at a distance of 2.25-0.3 Earth radii.
Section 4. Review of planets in the solar system that have a magnetic field
At present, the hypothesis of eddy electric currents flowing in the outer part of the planetary core, which exhibits some liquid properties, is almost generally accepted.
The Earth and eight other planets revolve around the Sun. (Fig. 11) It is one of the 100 billion stars that make up our Galaxy.
Fig. 11 Planets of the Solar System
Fig. 12 Mercury
High density Mercury leads to the conclusion that the planet has an iron-nickel core. We do not know whether Mercury's core is dense or, like Earth's, a mixture of dense and liquid matter. Mercury has a very strong magnetic field, suggesting that it retains a thin layer of molten material, possibly an iron-sulfur compound, surrounding a dense core.
Currents within this liquid surface layer explain the origin of the magnetic field. However, without the influence of the planet's rapid rotation, the movement of the liquid part of the core would be too insignificant to explain such a magnetic field strength. The magnetic field indicates that we are faced with “residual” core magnetism, “frozen” in the core as it solidified.
Venus
The density of Venus is only slightly less density Earth. From this it follows that its core occupies approximately 12% of the total volume of the planet, and the boundary between the core and the mantle is approximately halfway from the center to the surface. Venus doesn't have a magnetic field, and even if part of its core is liquid, we wouldn't expect a magnetic field to develop inside it because it rotates too slowly for the necessary currents to occur.
Fig.13 Earth
The Earth's strong magnetic field originates within a liquid outer core whose density suggests it is composed of a molten mixture of iron and a less dense element such as sulfur. Solid inner core consists predominantly of iron with the inclusion of a few percent of nickel.
Mars
Mariner 4 showed that there is no strong magnetic field on Mars, and therefore the planet’s core cannot be liquid. However, whenMars Global Surveyor approached the planet to within 120 km, it turned out that some areas of Mars have strong residual magnetism, possibly preserved from earlier times when the planet's core was liquid and could generate a powerful magnetic field.Mariner 4 showed that there is no strong magnetic field on Mars, and therefore the planet’s core cannot be liquid.
Fig. 14 Jupiter
Jupiter's core should be small, but most likely its mass is 10-20 times the mass of the Earth. We do not know the state of the rocky materials in Jupiter's core. Most likely they should be molten, but the enormous pressure can make it solid.
Jupiter has the most powerful magnetic field of all the planets in the solar system. It is 20,000 thousand greater than the power of the Earth's magnetic field. Jupiter's magnetic field is inclined relative to the planet's rotation axis by 9.6 degrees and is generated due to convection in a thick layer metallic hydrogen.
Fig. 15 Saturn
The internal structure of Saturn is comparable to the internal structure of the other giant planets. Saturn has a magnetic field that is 600 times stronger than the Earth's magnetic field. This is a peculiar version of Jupiter's field. The same auroras appear on Saturn. Their only difference from the Jupiterian ones is that they exactly coincide with the axis of rotation of the planet. Like Jupiter's field, Saturn's magnetic field is generated by convection processes occurring within a layer of metallic hydrogen.
Fig. 16 Uranus
Uranus has almost the same density as Jupiter. The rocky central core likely experiences a pressure of approximately 8 million atmospheres and a temperature of 8,000 0 . Uranus has a powerful magnetic field, about 50 times greater than the Earth's magnetic field. The magnetic field is inclined relative to the planet's rotation axis at an angle of 59 0 , which allows you to determine the speed of internal rotation. The center of symmetry of Uranus's magnetic field is located approximately one-third the distance from the center of the planet to its surface. This suggests that the magnetic field is generated by convection currents within the icy part of the planet's interior.
Fig. 17 Neptune
The internal structure is very similar to Uranus. Neptune's magnetic field is approximately 25 times greater than the Earth's magnetic field and 2 times weaker than the magnetic field of Uranus. Just like him. It is inclined at an angle of 47 degrees to the planet's rotation axis. Thus, we can say that Neptune's field arose as a result of convection currents into layers of liquid ice. In this case, the center of symmetry of the magnetic field lies quite far from the center of the planet, halfway from the center to the surface.
Pluto
We have concrete information about the internal structure of Pluto. The density suggests that beneath the icy mantle there most likely lies a rocky core, which contains about 70% of the planet's mass. It is quite possible that there is also a glandular nucleus inside the petrous core.
The realization that Pluto has similar properties to many Kuiper Belt objects has led many scientists to believe that Pluto should not be considered a planet, but rather classified as another Kuiper Belt object. The International Astronomical Union has put an end to this debate: based on historical precedent, Pluto will continue to be considered a planet for the foreseeable future.
Table 1 - “Basic astronomical characteristics of the planets.”
T Thus, we came to the conclusion: such a criterion as the magnetic field is a significant astronomical characteristic of the planets of the solar system.Most of the planets in the Solar System (Table 1) have magnetic properties to one degree or another.fields. In descending order of dipole magnetic moment, Jupiter is in first place andSaturn, followed by the Earth, Mercury and Mars, and in relation to the magnetic moment of the Earth the value of their moments is 20,000, 500, 1, 3/5000 3/10000.
Section 5. The role of the magnetic field in the existence and development of life on Earth
The Earth's magnetic field is weakening and this poses a serious threat to all life on the planet.According to scientists, this process began approximately 150 years ago and Lately accelerated. TOCurrently, the planet's magnetic field has weakened by approximately 10-15%.
During this process, scientists believe, the planet’s magnetic field will gradually weaken, thenwill practically disappear, and then reappear, but will have the opposite polarity.
Compass needles that previously pointed to the North Pole will begin to point to the South Polemagnetic pole, which will be replaced by the North Pole. Note that we are talking specifically about magnetic,and not about geographical poles.
The magnetic field plays very big role in the life of the Earth: on the one hand, it protectsplanet from a stream of charged particles flying from the Sun and from the depths of space, and on the other hand, it serveslike a road sign for living creatures migrating annually. What happens if thisthe field will disappear, no one can accurately predict, notesTheNewYorkTimes.
It can be assumed that while the pole change is taking place, many things in the sky and on earth willwill go wild. Pole reversal can result in accidents at high voltage lines, malfunctions of satellites, problems for astronauts. Reversing the polarity will lead to significantozone holes will expand, and the northern lights will begin to appear above the equator.
Animals that navigate using “natural” compasses will face serious problems.Fish, birds and animals will lose orientation and will not know which way to migrate.
However, according to some experts, our smaller brothers may not experiencesuch catastrophic problems. The movement of the poles will take about a thousand years.Experts believe that animals that navigate by magnetic power lines Earth,they will have time to adapt and survive.
Although the final reversal of the poles is likely to occur hundreds of years from now,this process is already causing damage to satellites. The last time such a cataclysm is believed to have occurredoccurred 780 thousand years ago.
Consequently: in epochs when the Earth does not have a magnetic field, its protective anti-radiation shield disappears. Significantly (several times) increase background radiation can significantly affect the biosphere.
Conclusion
The problem of studying magnetic is extremely relevant because...In epochs when the Earth does not have a magnetic field, its protective anti-radiation shield disappears. A significant (several times) increase in background radiation can significantly affect the biosphere: some groups of organisms should die out, among others the number of mutations may increase, etc. And if you take into account Solar flares, i.e. colossal explosions on the Sun that emit extremely strong streams cosmic rays, then it should be concluded that the eras of disappearance of the Earth’s magnetic field are eras of catastrophic influence on the biosphere from the Cosmos.
A magnetic field is a special form of matter through which interaction occurs between moving electrically charged particles.
Basic properties of the magnetic field:
A) The magnetic field is generated by electric current (moving charges).
b) A magnetic field is detected by its effect on current (moving charges),
The magnetic field is characterized by:
A) Magnetic induction B is the main force characteristic of a magnetic field.b) Magnetic field strength H is an auxiliary quantity.
Graphically, the magnetic field is represented using magnetic induction lines.
The most studied is the Earth's magnetic field. At any point in the space surrounding the Earth and on its surface, the action of magnetic forces is detected. North magnetic poleNlocated Southern Hemisphere, near the coast of Antarctica, and the south magnetic poleS. is located in the Northern Hemisphere, near the northern coast of Victoria Island (Canada). Both poles continuously move (act) on the earth's surface. In addition, the axis of the magnetic field does not pass through the center of the Earth, but lags behind it by 430 km. The Earth's magnetic field is not symmetrical. Due to the fact that the axis of the magnetic field passes at an angle of only 11.5 degrees to the axis of rotation of the planet, we can use a compass.
The source of the Earth's magnetic field has not yet been established by science, which deals only with an abundance of hypotheses put forward in this regard. The hypothesis, first of all, must explain the origin of the component of the Earth's magnetic field, due to which the planet behaves like a permanent magnet with a north magnetic pole near the south geographic pole and vice versa. Today, the hypothesis of eddy electric currents flowing in the outer part of the Earth's core, which exhibits some liquid properties, is almost generally accepted. It is calculated that the zone in which the “dynamo” mechanism operates is located at a distance of 2.25-0.3 Earth radii.It should be noted that the hypotheses explaining the mechanism of the emergence of the magnetic field of planets are quite contradictory and have not yet been confirmed
Most of the planets in the solar system have magnetic properties to one degree or another.fields. We have collected from various sources and systematized data on the characteristics of various planets of the solar system. We supplemented the generally accepted table “Basic astronomical characteristics of planets” with these data. We believe that the “Magnetic field” criterion is one of the leading characteristics of the planets of the solar system. In descending order of dipole magnetic moment, Jupiter is in first place andSaturn, followed by the Earth, Mercury and Mars, and in relation to the magnetic moment of the Earth, the value of their moments is 20,000, 500, 1, 3/5000, 3/10000..
6. The theoretical significance of the study is that:
1) material about the Magnetic field of the Earth and the planets of the Solar system is systematized;
2) The leading physical characteristics of the magnetic field of the planets of the solar system have been clarified and the table “Basic astronomical characteristics of the planets” with data on the magnetic fields of the solar system has been supplemented;
In addition, the theoretical significance on the topic “Magnetic field of the planets of the solar system” allowed me to expand my knowledge of physics and astronomy
Used Books
1 .Govorkov V. A. Electric and magnetic fields. “Energy”, M, 1968 – 50 p.
2. David Rothery Planets, Fair-Press”, M, 2005 – 320 p.
3 .Tamm I.E. About currents in the ionosphere that cause variations in the earth's magnetic field. Meeting scientific works, vol. 1, “Science”, M., 1975 – 100 p.
4. Yanovsky B. M. Terrestrial magnetism. “Publishing house Leningrad University" Leningrad, 1978 – 75 p.
Papplication
Thesaurus
G az giants are the two largest giant planets (Jupiter and Saturn), which have a deeper outer layer of gas than the other two giant planets.
G giant planets - four largest planets, located in the outer region of the Solar System (Jupiter, Saturn, Uranus and Neptune), whose mass is tens or hundreds of times greater than the mass of the Earth and which do not have a solid surface.
TO The oyper belt is a region of the solar system located beyond the orbit of Neptune at a distance of 30-50.au. From the Sun, inhabited by small, icy, subplanetary-sized objects called (with the exception of Pluto and its moon Charon, which are largest bodies this region) by Kuiper Belt objects. The existence of the Kuiper belt is theoretically predicted by Kenneth Edgeworth (1943) and the Edgeworth-Copeyr (or disk). The objects located in it are called Kuiper belt objects or Edgeworth-Copeyr objects.
TO ora - the outer, chemically different layer of a solid planetary body. On the planets earth type K. is rocky and contains large quantity elements of lower density than the underlying mantle. On icy satellites or bodies similar to them, calcium (where it exists) is richer in salts and flying ice than the underlying icy mantle.
L units- this term is sometimes used to refer to frozen water, but can also refer to other volatile substances in the frozen state (methane, ammonia, carbon monoxide, carbon dioxide and nitrogen - either individually or in combination).
M Antiya- a compositionally distinct rock lying outside the core of a solid planetary body. Terrestrial planets have rocky planets, while icy satellites have icy ones. In some cases, the outer chemical rock differs slightly from the composition of the rock itself. In this case, it is called bark.
P planet - one of the large objects revolving around the Sun (or another star). Nine bodies (Mercury, Venus, Pluto) are called the planets of our solar system. Precise definition impossible to give, since Pluto, apparently, is an exceptionally large Kuiper belt object (most such objects are too small to be considered Pluto), while some satellites of Pluto, in terms of their size, composition and other characteristics, could well be I would call it P.
P terrestrial planets- The Earth and similar celestial bodies (having a ferrous core and a rocky surface). Such planets include Mercury, Venus and Mars. These also include the Moon and the large satellite of Jupiter-Io.
P recession - slow movement of the Earth's axis of rotation along circular cone with an axis, angle 23-27 degrees.
Period full turn is about 26 thousand years. As a result of P., the position of the celestial equator changes; points of the spring and autumn equinoxes of copper annual movement Sun by 50.24 seconds per year; the plus of the world moves between the stars; The equatorial coordinates of stars are constantly changing.
P rograde motion - reversal or rotation in a counterclockwise direction when viewed from north pole Sun (or Earth). If we talk about satellites, orbital motion is considered prograde if it coincides with the direction of rotation of the planet. Most movements in the solar system are prograde.
R Retrograde motion - reversal or rotation directed clockwise when viewed from the north pole of the Sun (or Earth). It is the opposite of prograde movement. If we talk about satellites, if it is opposite to the direction of rotation of the planet.
WITH solar system - Sun and bodies gravitationally associated with it (that is, planets, their satellites, asteroids, Kuiper belt objects, comets, etc.).
I draw - the dense inner region of a planetary body, which differs in composition from the rest of the planet. Ya lies below the mantle. I.terrestrial planets are rich in iron. Large icy satellites and giant planets have rocky cores, within which there may also be ferruginous cores.
Magnetic shields of planets. On the diversity of sources of magnetospheres in the solar system
- Popular Science,
- Cosmonautics,
- Astronomy
6 out of 8 planets in the solar system have their own sources of magnetic fields that can deflect streams of charged particles from the solar wind. The volume of space around the planet within which the solar wind deviates from its trajectory is called the planet’s magnetosphere. Despite the commonality of the physical principles of magnetic field generation, the sources of magnetism, in turn, vary greatly among different groups planets of our star system.
The study of the diversity of magnetic fields is interesting because the presence of the magnetosphere is presumably an important condition for the emergence of life on a planet or its natural satellite.
Iron and stone
For terrestrial planets, strong magnetic fields are the exception rather than the rule. Our planet has the most powerful magnetosphere in this group. Solid core The Earth supposedly consists of an iron-nickel alloy heated by the radioactive decay of heavy elements. This energy is transferred by convection in the liquid outer core into the silicate mantle (). Thermal convective processes in the metallic outer core were until recently considered the main source of the geomagnetic dynamo. However, research in recent years has refuted this hypothesis.
Interaction of the magnetosphere of a planet (in this case, the Earth) with the solar wind. Streams of solar wind deform the magnetospheres of planets, which have the appearance of a highly elongated magnetic “tail” directed in the direction opposite to the Sun. Jupiter's magnetic tail stretches for more than 600 million km.
Presumably, the source of magnetism during the existence of our planet could be complex combination various mechanisms for generating a magnetic field: primary initialization of the field from an ancient collision with a planetoid; non-thermal convection of various phases of iron and nickel in the outer core; releasing magnesium oxide from the cooling outer core; tidal influence of the Moon and Sun, etc.
The bowels of the “sister” of the Earth - Venus practically do not generate a magnetic field. Scientists are still debating the reasons for the lack of a dynamo effect. Some blame the slow daily rotation of the planet for this, while others argue that this should have been enough to generate a magnetic field. Most likely it's a matter of internal structure planet other than Earth ().
It is worth mentioning that Venus has a so-called induced magnetosphere, created by the interaction of the solar wind and the planet’s ionosphere
Mars is closest (if not identical) to Earth in terms of sidereal day length. The planet rotates around its axis in 24 hours, just like the two “colleagues” described above, the giant consists of silicates and a quarter of the iron-nickel core. However, Mars is an order of magnitude lighter than Earth, and, according to scientists, its core cooled relatively quickly, so the planet does not have a dynamo generator.
Internal structure of iron silicate planets of the terrestrial group
Paradoxically, the second planet in the terrestrial group that can “boast” of its own magnetosphere is Mercury - the smallest and lightest of all four planets. Its proximity to the Sun predetermined the specific conditions under which the planet formed. So, unlike the other planets of the group, Mercury has an extremely high relative proportion of iron to the mass of the entire planet - on average 70%. Its orbit has the strongest eccentricity (the ratio of the point of the orbit closest to the Sun to the most distant) among all the planets in the solar system. This fact, as well as the proximity of Mercury to the Sun, increase the tidal influence on the iron core of the planet.
Diagram of Mercury's magnetosphere with a superimposed graph of magnetic induction
Scientific data obtained spacecraft, suggest that the magnetic field is generated by the movement of metal in the core of Mercury, molten by the tidal forces of the Sun. Magnetic moment this field is 100 times weaker than the Earth’s, and its dimensions are comparable to the size of the Earth, not last resort because of strong influence solar wind.
Magnetic fields of the Earth and giant planets. Red line - axis daily rotation planets (2 - the inclination of the magnetic field poles to a given axis). The blue line is the equator of the planets (1 - the inclination of the equator to the ecliptic plane). Magnetic fields are represented in yellow (3 - magnetic field induction, 4 - radius of magnetospheres in the radii of the corresponding planets)
Metal giants
The giant planets Jupiter and Saturn have large rock cores with a mass of 3-10 Earth's, surrounded by powerful gas shells, which account for the vast majority of the mass of the planets. However, these planets have extremely large and powerful magnetospheres, and their existence cannot be explained only by the dynamo effect in the rocky cores. And it is doubtful that, with such colossal pressure, phenomena similar to those occurring in the Earth’s core are even possible there.The key to the solution lies in the hydrogen-helium shell of the planets itself. Mathematical models show that in the depths of these planets, hydrogen from a gaseous state gradually transforms into the state of a superfluid and superconducting liquid - metallic hydrogen. It is called metallic because at such pressure values hydrogen exhibits the properties of metals.
Internal structure of Jupiter and Saturn
Jupiter and Saturn, as is typical for giant planets, retained in their depths a large amount of thermal energy accumulated during the formation of the planets. Convection of metallic hydrogen transfers this energy into the gaseous shell of the planets, determining the climate in the atmospheres of the giants (Jupiter emits twice as much energy into space as it receives from the Sun). Convection in metallic hydrogen, combined with the rapid daily rotation of Jupiter and Saturn, presumably form the powerful magnetospheres of the planets.
At the magnetic poles of Jupiter, as well as at the similar poles of the other giants and the Earth, the solar wind causes “polar” auroras. In the case of Jupiter, its magnetic field is significantly influenced by such large satellites as Ganymede and Io (a trace of streams of charged particles “flowing” from the corresponding satellites to the magnetic poles of the planet is visible). Studying Jupiter's magnetic field is the main task of the Juno automatic station operating in its orbit. Understanding the origin and structure of the magnetospheres of the giant planets can enrich our knowledge of the Earth's magnetic field
Ice generators
The ice giants Uranus and Neptune are so similar in size and mass that they can be called the second pair of twins in our system, after Earth and Venus. Their powerful magnetic fields occupy an intermediate position between the magnetic fields of the gas giants and the Earth. However, here too nature “decided” to be original. The pressure in the rock-iron cores of these planets is still too high for a dynamo effect like Earth's, but not enough to form a layer of metallic hydrogen. The planet's core is surrounded by a thick layer of ice made from a mixture of ammonia, methane and water. This "ice" is actually an extremely heated liquid that does not boil solely due to the enormous pressure of the planets' atmospheres.
Internal structure of Uranus and Neptune
The terrestrial group has its own magnetic field. The giant planets and Earth have the strongest magnetic fields. The source of a planet's dipole magnetic field is often considered to be its molten conductive core. Venus and Earth have similar sizes, average density and even internal structure, however, the Earth has a fairly strong magnetic field, but Venus does not (the magnetic moment of Venus does not exceed 5-10% of the Earth's magnetic field). According to one of the modern theories, the strength of the dipole magnetic field depends on the precession of the polar axis and the angular velocity of rotation. It is these parameters that are negligibly small on Venus, but measurements indicate even lower tension than theory predicts. Current assumptions about Venus' weak magnetic field are that there are no convective currents in Venus' supposedly iron core.
Notes
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Books
- Misconceptions and errors of fundamental concepts of physics, Yu. I. Petrov. This book identifies and demonstrates hidden or obvious errors in mathematical constructions of general and special theory relativity, quantum mechanics, as well as surface...