Travel time of the solar wind to the earth. What is solar wind and how does it arise? Can a person feel the solar wind?

Can reach values ​​up to 1.1 million degrees Celsius. Therefore, having such a temperature, the particles move very quickly. The Sun's gravity cannot hold them - and they leave the star.

The sun's activity varies over an 11-year cycle. At the same time, the number of sunspots, radiation levels and the mass of material ejected into space change. And these changes affect the properties of the solar wind - its magnetic field, speed, temperature and density. That's why sunny wind may have different characteristics. They depend on where exactly its source was located on the Sun. And they also depend on how fast this area rotated.

The speed of the solar wind is higher than the speed of movement of the material of the coronal holes. And reaches 800 kilometers per second. These holes appear at the poles of the Sun and in its low latitudes. They become largest in size during periods when activity on the Sun is minimal. Temperatures of material carried by the solar wind can reach 800,000 C.

In the coronal streamer belt located around the equator, the solar wind moves more slowly - about 300 km. per second. It has been established that the temperature of matter moving in the slow solar wind reaches 1.6 million C.

The sun and its atmosphere are composed of plasma and a mixture of positively and negatively charged particles. They have extremely high temperatures. Therefore, matter constantly leaves the Sun, carried away by the solar wind.

Impact on Earth

When the solar wind leaves the Sun, it carries charged particles and magnetic fields. Solar wind particles emitted in all directions constantly impact our planet. This process produces interesting effects.

If material carried by the solar wind reaches the planet's surface, it will cause severe damage to any form of life that exists on. Therefore, the Earth's magnetic field serves as a shield, redirecting trajectories solar particles around the planet. Charged particles seem to “flow” outside of it. The influence of the solar wind changes the Earth's magnetic field in such a way that it is deformed and stretched on the night side of our planet.

Sometimes the Sun ejects large volumes of plasma known as coronal mass ejections (CMEs), or solar storms. This most often occurs during the active period of the solar cycle, known as solar maximum. CMEs have a stronger effect than the standard solar wind.

Some bodies in the solar system, like the Earth, are shielded by a magnetic field. But many of them do not have such protection. Our Earth's satellite has no protection for its surface. Therefore, it experiences maximum exposure to solar wind. Mercury, the closest planet to the Sun, has a magnetic field. It protects the planet from normal standard winds, but it is not able to withstand more powerful flares such as CMEs.

When high- and low-speed solar winds interact with each other, they create dense regions known as rotating interacting regions (CIRs). It is these areas that cause geomagnetic storms when they collide with the earth's atmosphere.

The solar wind and the charged particles it carries can influence Earth satellites and Global Positioning Systems (GPS). Powerful bursts can damage satellites or cause position errors when using GPS signals tens of meters away.

The solar wind reaches all planets in . NASA's New Horizons mission discovered it while traveling between and.

Studying the solar wind

Scientists have known about the existence of solar wind since the 1950s. But despite its serious impact on Earth and astronauts, scientists still don't know many of its characteristics. Several space missions in recent decades have attempted to explain this mystery.

Launched into space on October 6, 1990, NASA's Ulysses mission studied the Sun at different latitudes. She measured various properties of the solar wind for more than ten years.

The Advanced Composition Explorer mission had an orbit associated with one of the special points located between the Earth and the Sun. It is known as the Lagrange point. In this region, gravitational forces from the Sun and Earth are equally important. And this allows the satellite to have a stable orbit. Begun in 1997, the ACE experiment studies the solar wind and provides measurements of the constant flux of particles in real scale time.

NASA's STEREO-A and STEREO-B spacecraft study the edges of the Sun from different angles to see how the solar wind is generated. According to NASA, STEREO provided a "unique and revolutionary view of the Earth-Sun system."

New missions

NASA is planning to launch a new mission to study the Sun. It gives scientists hope to learn even more about the nature of the Sun and solar wind. NASA Parker solar probe planned for launch ( successfully launched 08/12/2018 – Navigator) in the summer of 2018, will work in such a way as to literally “touch the Sun”. After several years of flight in orbit close to our star, the probe will plunge into the solar corona for the first time in history. This will be done in order to obtain a combination of fantastic images and measurements. The experiment will advance our understanding of the nature of the solar corona, and improve understanding of the origin and evolution of the solar wind.

Constant radial flow of solar plasma. crowns in interplanetary production. The flow of energy coming from the depths of the Sun heats the corona plasma to 1.5-2 million K. DC. heating is not balanced by energy loss due to radiation, since the density of the corona is low. Excess energy means. degrees are carried away by the S. century. (=1027-1029 erg/s). The crown, therefore, is not in a hydrostatic position. equilibrium, it continuously expands. According to the composition of the S. century. does not differ from corona plasma (solar plasma contains mainly protons, electrons, some helium nuclei, oxygen, silicon, sulfur, and iron ions). At the base of the corona (10 thousand km from the photosphere of the Sun), particles have a radial velocity of the order of hundreds of m/s, at a distance of several. solar radii it reaches the speed of sound in plasma (100 -150 km/s), near the Earth's orbit the speed of protons is 300-750 km/s, and their spaces. concentration - from several. h-ts to several tens of hours in 1 cm3. With the help of interplanetary space. stations it was established that up to the orbit of Saturn the density flow h-c S.v. decreases according to the law (r0/r)2, where r is the distance from the Sun, r0 is the initial level. S.v. carries with it the loops of the solar power lines. mag. fields, which form the interplanetary magnetic field. field. The combination of radial movement h-c S. v. with the rotation of the Sun it gives these lines the shape of spirals. Large-scale structure of mag. The fields in the vicinity of the Sun have the form of sectors, in which the field is directed from the Sun or towards it. The size of the cavity occupied by the S. v. is not precisely known (its radius is apparently no less than 100 AU). At the boundaries of this cavity there is a dynamic blood pressure must be balanced by the pressure of interstellar gas, galactic. mag. fields and galactic space rays. In the vicinity of the Earth, the collision of the flow of h-c S. v. with geomagnetic field generates a stationary shock wave in front of the earth's magnetosphere (from the side of the Sun, Fig.).

The influence of the solar wind on the Earth's magnetosphere: 1 - magnetic field lines. fields of the Sun; 2 - shock wave; 3 - Earth's magnetosphere; 4 - magnetosphere boundary; 5 - Earth's orbit; 6 - trajectory of the solar wind. S.v. flows around the magnetosphere, as it were, limiting its extent in space. Changes in solar intensity associated with solar flares, phenomena. basic cause of geomagnetic disturbances. fields and magnetosphere (magnetic storms). Over the course of a year, the Sun loses from the north. =2X10-14 part of its mass Msol. It is natural to assume that an outflow of matter similar to the S.E. also exists in other stars (). It should be especially intense in massive stars (with mass = several tens of Msolns) and with high surface temperatures (= 30-50 thousand K) and in stars with an extended atmosphere (red giants), because in In the first case, the particles of a highly developed stellar corona have a sufficiently high energy to overcome the gravity of the star, and in the second, the parabolic energy is low. speed (escaping speed; (see SPACE SPEEDS)). Means. Mass losses with stellar wind (= 10-6 Msol/year and more) can significantly affect the evolution of stars. In turn, the stellar wind creates hot gas in the interstellar medium - sources of X-rays. radiation.

A continuous stream of plasma of solar origin, spreading approximately radially from the Sun and filling the solar system to the heliocentric. distances R ~ 100 a. e. S. v. gas-dynamic is formed. expansion of the solar corona (see Sun) into interplanetary space. At high temperatures, which exist in the solar corona (1.5 * 10 9 K), the pressure of the overlying layers cannot balance the gas pressure of the corona substance, and the corona expands.

The first evidence of the existence of post. plasma flows from the Sun were obtained by L. L. Biermann in the 1950s. on the analysis of forces acting on the plasma tails of comets. In 1957, Yu. Parker (E. Parker), analyzing the conditions of equilibrium of the corona matter, showed that the corona cannot be in hydrostatic conditions. in 1959. Existence post. the outflow of plasma from the Sun was proven as a result of many months of measurements in America. space apparatus in 1962.

Wed. characteristics of S. v. are given in table. 1. S. flows. can be divided into two classes: slow - with a speed of 300 km/s and fast - with a speed of 600-700 km/s. Fast flows come from regions of the solar corona, where the structure of the magnetic field. fields are close to radial. coronal holes. Slow streamsS. V. are apparently associated with the areas of the crown, in which there is, therefore, Table 1. - Average characteristics of the solar wind in Earth orbit

Speed
Proton concentration
Proton temperature
Electron temperature
Tension magnetic field
Python flux density....	2.4*10 8 cm -2 *c -1
Kinetic energy flux density	0.3 erg*cm -2 *s -1

Table 2.- Relative chemical composition of the solar wind

	Relative content

	Relative content

In addition to the main components of solar water - protons and electrons; particles were also found in its composition. Measurements of ionization. temperature of ions S. v. make it possible to determine the electron temperature of the solar corona.

In the N. century. differences are observed. types of waves: Langmuir, whistlers, ion-acoustic, waves in plasma). Some of the Alfven type waves are generated on the Sun, and some are excited in the interplanetary medium. The generation of waves smoothes out deviations of the particle distribution function from the Maxwellian one and, in combination with the influence of magnetism. fields to plasma leads to the fact that S. v. behaves like a continuous medium. Alfvén-type waves play a large role in the acceleration of small components of S.

Rice. 1. Mass spectrum of the solar wind. Along the horizontal axis is the ratio of the mass of a particle to its charge, along the vertical axis is the number of particles registered in the energy window of the device in 10 s. Numbers with an icon indicate the charge of the ion.

Stream N. in. is supersonic in relation to the speeds of those types of waves that provide eff. transfer of energy to the S. century. (Alfven, sound and magnetosonic waves). Alfven and sound Mach number C. V. 7. When flowing around the north side. obstacles capable of effectively deflecting it (magnetic fields of Mercury, Earth, Jupiter, Saturn or the conducting ionospheres of Venus and, apparently, Mars), a departing bow shock wave is formed. Magnetosphere of the Earth, Magnetospheres of the planets). In case of interaction with S. v. with a non-conducting body (for example, the Moon), a shock wave does not occur. The plasma flow is absorbed by the surface, and a cavity is formed behind the body, gradually filled with plasma C. V.

The stationary process of corona plasma outflow is superimposed by non-stationary processes associated with flares on the Sun. During strong flares, substances are released from the bottom. corona regions into the interplanetary medium. Magnetic variations).

Rice. 2. Propagation of an interplanetary shock wave and ejection from a solar flare. The arrows indicate the direction of motion of the solar wind plasma,

Rice. 3. Types of solutions to the corona expansion equation. The speed and distance are normalized to the critical speed vk and the critical distanceRk. Solution 2 corresponds to the solar wind.

The expansion of the solar corona is described by a system of mass conservation equations, v k) at some critical point. distance R to and subsequent expansion at supersonic speed. This solution gives a vanishingly small value of pressure at infinity, which makes it possible to reconcile it with the low pressure of the interstellar medium. This type of flow was called S. by Yu. Parker. , where m is the proton mass, is the adiabatic exponent, and is the mass of the Sun. In Fig. Figure 4 shows the change in expansion rate from heliocentric.

Rice. 4. Solar wind speed profiles for the isothermal corona model at different values ​​of coronal temperature.

S.v. provides the basic outflow of thermal energy from the corona, since heat transfer to the chromosphere, el.-magn. Corona radiation and electronic thermal conductivitypp. V. are insufficient to establish the thermal balance of the corona. Electronic thermal conductivity ensures a slow decrease in the ambient temperature. with distance. luminosity of the Sun.

S.v. carries the coronal magnetic field with it into the interplanetary medium. field. The force lines of this field frozen into the plasma form an interplanetary magnetic field. field (MMP). Although the IMF intensity is low and its energy density is about 1% of the kinetic density. energy of solar energy, it plays an important role in thermodynamics. V. and in the dynamics of interactions of S. v. with the bodies of the solar system, as well as the streams of the north. between themselves. Combination of expansion of the S. century. with the rotation of the Sun leads to the fact that the mag. the lines of force frozen into the north of the century have the form B R and azimuthal magnetic components. fields change differently with distance near the ecliptic plane:

where is ang. speed of rotation of the Sun, And - radial component of velocityC. c., index 0 corresponds to the initial level. At the distance of the Earth's orbit, the angle between the magnetic direction. fields and R about 45°. At large L magnetic.

Rice. 5. Shape of the interplanetary magnetic field line. - angular velocity of rotation of the Sun, and - radial component of plasma velocity, R - heliocentric distance.

S. v., arising over regions of the Sun with different. magnetic orientation fields, speed, temp-pa, particle concentration, etc.) also in cf. change naturally in the cross section of each sector, which is associated with the existence of a fast flow of solar water within the sector. The boundaries of the sectors are usually located within the slow flow of the North century. Most often, 2 or 4 sectors are observed, rotating with the Sun. This structure, formed when the S. is pulled out. large-scalemagn. corona fields, can be observed for several. revolutions of the Sun. The sector structure of the IMF is a consequence of the existence of a current sheet (CS) in the interplanetary medium, which rotates together with the Sun. TS creates a magnetic surge. fields - radial components of the IMF have different signs on different sides of the vehicle. This TC, predicted by H. Alfven, passes through those parts of the solar corona that are associated with active regions on the Sun, and separates these regions from the different ones. signs of the radial component of the solar magnet. fields. The TS is located approximately in the plane of the solar equator and has a folded structure. The rotation of the Sun leads to the twisting of the folds of the TC into a spiral (Fig. 6). Being near the ecliptic plane, the observer finds himself either above or below the TS, due to which he falls into sectors with different signs of the IMF radial component.

Near the Sun in the north. there are longitudinal and latitudinal gradients of the velocity of collisionless shock waves (Fig. 7). First, a shock wave is formed, propagating forward from the boundary of the sectors (direct shock wave), and then a reverse shock wave is formed, propagating towards the Sun.

Rice. 6. Shape of the heliospheric current layer. Its intersection with the ecliptic plane (inclined to the solar equator at an angle of ~ 7°) gives the observed sector structure of the interplanetary magnetic field.

Rice. 7. Structure of the interplanetary magnetic field sector. Short arrows show the direction of solar wind plasma flow, arrowed lines indicate magnetic field lines, dash-dotted lines indicate sector boundaries (the intersection of the drawing plane with the current sheet).

Since the speed of the shock wave is less than the speed of the solar energy, the plasma entrains the reverse shock wave in the direction away from the Sun. Shock waves near sector boundaries are formed at distances of ~1 AU. e. and can be traced to distances of several. A. e. These shock waves, as well as interplanetary shock waves from solar flares and circumplanetary shock waves, accelerate particles and are, therefore, a source of energetic particles.

S.v. extends to distances of ~100 AU. e., where the pressure of the interstellar medium balances the dynamic. blood pressure The cavity swept by the S. v. Interplanetary environment). ExpandingS. V. along with the magnet frozen into it. field prevents the penetration of galactic particles into the solar system. space rays of low energies and leads to cosmic variations. high energy rays. A phenomenon similar to the S.V. has been discovered in some other stars (see. Stellar wind).

Concept sunny wind was introduced into astronomy in the late 40s of the 20th century, when the American astronomer S. Forbush, measuring the intensity of cosmic rays, noticed that it decreased significantly with increasing solar activity and drops quite sharply during .

This seemed quite strange. Rather, one would expect the opposite. After all, the Sun itself is a supplier of cosmic rays. Therefore, it would seem that the higher the activity of our daylight, the more particles it should emit into the surrounding space.

It remains to be assumed that the increase in solar activity affects in such a way that it begins to deflect cosmic ray particles - to throw them away.

It was then that the assumption arose that the culprits of the mysterious effect were streams of charged particles escaping from the surface of the Sun and penetrating space solar system. This peculiar solar wind cleanses the interplanetary medium, “sweeping” particles of cosmic rays out of it.

Such a hypothesis was also supported by phenomena observed in. As you know, comet tails are always directed away from the Sun. Initially, this circumstance was associated with light pressure sun rays. However, it was found that light pressure alone cannot cause all the phenomena occurring in comets. Calculations have shown that for the formation and observed deflection of cometary tails, the action of not only photons, but also particles of matter is necessary.

As a matter of fact, it was known before that the Sun emits streams of charged particles - corpuscles. However, it was assumed that such flows were episodic. But cometary tails are always directed in the direction opposite to the Sun, and not just during periods of intensification. This means that corpuscular radiation filling the space of the solar system must exist constantly. It intensifies with increasing solar activity, but always exists.

Thus, the solar wind continuously blows around the solar space. What does this solar wind consist of, and under what conditions does it arise?

The outermost layer of the solar atmosphere is the "corona". This part of the atmosphere of our daylight is unusually rarefied. But the so-called “kinetic temperature” of the corona, determined by the speed of particle movement, is very high. It reaches a million degrees. Therefore, coronal gas is completely ionized and is a mixture of protons, ions of various elements and free electrons.

Recently it was reported that the solar wind contains helium ions. This circumstance sheds light on the mechanism by which charged particles are ejected from the surface of the Sun. If the solar wind consisted only of electrons and protons, then one could still assume that it is formed due to purely thermal processes and is something like steam formed above the surface of boiling water. However, the nuclei of helium atoms are four times heavier than protons and are therefore unlikely to be ejected through evaporation. Most likely, the formation of the solar wind is associated with the action magnetic forces. Flying away from the Sun, plasma clouds seem to take magnetic fields with them. It is these fields that serve as that kind of “cement” that “fastens” together particles with different masses and charges.

Observations and calculations carried out by astronomers have shown that as we move away from the Sun, the density of the corona gradually decreases. But it turns out that in the region of the Earth’s orbit it is still noticeably different from zero. In other words, our planet is located inside the solar atmosphere.

If the corona is more or less stable near the Sun, then as the distance increases it tends to expand into space. And the further from the Sun, the higher the speed of this expansion. According to the calculations of the American astronomer E. Parker, already at a distance of 10 million km, coronal particles move at speeds exceeding the speed.

Thus, the conclusion suggests itself that the solar corona is the solar wind blowing through the space of our planetary system.

These theoretical conclusions were fully confirmed by measurements on space rockets and artificial Earth satellites. It turned out that the solar wind always exists near the Earth - it “blows” at a speed of about 400 km/sec.

How far does the solar wind blow? Based on theoretical considerations, in one case it turns out that the solar wind subsides already in the region of the orbit, in the other - that it still exists at a very large distance beyond the orbit of the last planet Pluto. But these are only theoretically extreme limits of the possible propagation of the solar wind. Only observations can indicate the exact boundary.

There is a constant stream of particles ejected from the Sun's upper atmosphere. We see evidence of the solar wind all around us. Powerful geomagnetic storms can damage satellites and electrical systems on Earth, and cause beautiful auroras. Perhaps the best evidence of this is the long tails of comets when they pass close to the Sun.

Dust particles from a comet are deflected by the wind and carried away from the Sun, which is why the tails of comets are always directed away from our star.

Solar wind: origin, characteristics

It comes from the Sun's upper atmosphere, called the corona. In this region, the temperature is more than 1 million Kelvin, and the particles have an energy charge of more than 1 keV. There are actually two types of solar wind: slow and fast. This difference can be seen in comets. If you look at the image of a comet closely, you will see that they often have two tails. One of them is straight and the other is more curved.

Solar wind speed online near Earth, data for the last 3 days

Fast solar wind

It is moving at a speed of 750 km/s, and astronomers believe it originates from coronal holes - regions where magnetic field lines make their way to the surface of the Sun.

Slow solar wind

It has a speed of about 400 km/s, and comes from the equatorial belt of our star. The radiation reaches the Earth, depending on the speed, from several hours to 2-3 days.

People are getting more and more attention interesting facts about the solar wind. What is this phenomenon? In the late 1940s, savvy astrophysicists concluded that the Sun was collecting gaseous substances from interstellar outer space. For this reason, the theory was put forward about the existence of wind directed towards the sun. After some time, scientists were even able to confirm the existence of the solar wind, but with a slight amendment: the wind comes from the Sun in different directions. Let's look at a few interesting facts about this phenomenon:

1. First of all, you need to know that the definition of “solar wind” describes an astrophysical phenomenon, not a meteorological one. This process is a continuous radiation of plasma into the surrounding space. Through this wind, the Sun seems to remove the excess energy contained in it.
2. In fact, instead of accumulating substances from the surrounding outer space, the Sun throws out in different directions the substance it contains in a volume equal to one million tons per period corresponding to one revolution of the Earth around its axis.
3. The speed of particles moving away from the Sun is constantly increasing, since they are pushed by similar matter, the temperature of which is much higher. In addition, the force of attraction of the Sun gradually ceases to act on plasma particles, which are components of the flows.

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4. At approximately 20,000 km from the surface, the speed of plasma particles can correspond to tens of thousands of meters per second. After traveling a distance corresponding to several diameters of the sun, the speed of the plasma particles becomes a thousand times greater. Near our planet, this speed becomes hundreds of times higher, and their density becomes much lower than that of the atmosphere.

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5. The flow mostly includes protons and electrons, but it also contains nuclei of helium and other elements.

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6. Temperature of plasma particles located at the very beginning of the flows solar winds corresponds to approximately two million degrees Kelvin. As you move away, the temperature first increases to 20 million degrees and only then begins to decrease. When the wind flows reach our planet, the plasma particles cool to about 10,000 degrees.
7. When solar flares occur, the temperature of the plasma near the Earth corresponds to 100 thousand degrees.

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8. Our planet's magnetic field protects us well from this radiation. Streams of solar winds literally flow around the earth's atmosphere and sweep further into the surrounding space, gradually reducing their density.
9. From time to time, the intensity of passing streams of plasma particles is so high that the atmosphere of our planet has difficulty reflecting their impact. Naturally, the solar wind flows recede, but only after some time.

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10. When powerful streams of solar winds interact intensively with the magnetic field of our planet, we can observe auroras in the polar regions, and also record the formation of magnetic storms.

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11. The distribution of solar winds cannot be called uniform. The distribution speed can reach its maximum when the wind passes over the so-called coronal holes. The slowest flow of streams can be recorded above streamers. Streams with different flow rates intersect with each other and with our planet.

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12. We have learned to obtain the greatest amount of information about the solar wind thanks to specially developed spacecraft. The list of such technological devices includes the well-known Ulysses satellite, thanks to which our knowledge of the solar wind has changed significantly. Chemical composition and the speed of plasma flows were studied thanks to such a remarkable device. Additionally, with the help of the satellite, it was possible to determine the level of the magnetic field of our planet.
13. Another ACE satellite was launched into orbit back in 1997 near the L1 Lagrange point. It is at this point that solar and earth's gravity are in balance. On board this machine there are devices that continuously monitor the flow of solar winds so that people can explore information about directional plasma particles in real time, limited to the territory of the L1 sector.
14. Recently, the solar wind caused a geomagnetic storm on Earth. Intense flows came out of the coronary opening into solar atmosphere. Such holes can form in the luminary even in cases where there is a complete absence of active zones.
15. Today, a coronal hole has formed on the Sun.. Streams of plasma particles with a high distribution density reached the planet by mid-June, which caused the development of geomagnetic storms.