Sun: structure, characteristics, interesting facts, photos, videos. Sun: structure, characteristics, interesting facts, photo, video The passage of starlight through the solar corona

Eclipses are among the most spectacular astronomical phenomena. However, no technical means can fully convey the sensations arising from the observer. And yet, due to the imperfection of the human eye, he does not see everything at once. The details of this wonderful picture, eluding the eye, can only be revealed and captured by a special technique of photographing and signal processing. The variety of eclipses is far from exhausted by the phenomena in the Sun-Earth-Moon system. Relatively close space bodies regularly cast shadows on each other (it is only necessary that there is some powerful source of light radiation nearby). Watching this cosmic shadow theater, astronomers get a lot of interesting information about the structure of the universe. Photo Vyacheslav Khondyrev

In the Bulgarian resort of Shabla, August 11, 1999 was the most ordinary summer day. Blue sky, golden sand, warm gentle sea. But no one went into the water on the beach - the public was preparing for observations. It was here that a hundred-kilometer spot of the lunar shadow should have crossed the Black Sea coast, and the duration of the full phase, according to calculations, reached 3 minutes 20 seconds. The excellent weather quite corresponded to long-term data, but everyone looked with alarm at the cloud hanging over the mountains.

In fact, the eclipse was already underway, just few people were interested in its partial phases. Another thing is the full phase, before the start of which there was still half an hour. A brand new digital SLR, specially bought for this occasion, was in full readiness. Everything is thought out to the smallest detail, each movement is rehearsed dozens of times. The weather would not have time to deteriorate, and yet, for some reason, anxiety was growing. Maybe the fact is that the light has noticeably diminished and it has become sharply colder? But this is how it should be with the approach of the full phase. However, the birds do not understand this - all the birds capable of flying rose into the air and shouted out circles above our heads. The wind blew from the sea. Every minute he grew stronger, and the heavy camera began to tremble on a tripod, which until recently seemed so reliable.

There is nothing to do - a few minutes before the calculated moment, at the risk of spoiling everything, I went down from the sandy hill to its foot, where the bushes extinguished the wind. A few movements, and literally at the last moment the technique is again set up. But what is this noise? Dogs bark and howl, sheep bleat. It seems that all animals capable of making sounds do it as if for the last time! The light is fading every second. Birds in the darkened sky are no longer visible. Everything subsides at once. The filamentous crescent of the sun illuminates the seashore no brighter than the full moon. Suddenly, he goes out. Who followed him in the last seconds without a dark filter, in the first moments, he probably does not see anything.

My fussy excitement was replaced by a real shock: the eclipse, which I have dreamed of all my life, has already begun, precious seconds are flying, and I can’t even raise my head and enjoy the rarest sight - taking pictures first of all! Each time the button is pressed, the camera automatically takes a series of nine shots (in “bracketing” mode). One more. More and more. While the camera clicks the shutter, I still dare to break away and look at the crown through binoculars. From the black moon, many long rays scattered in all directions, forming a pearl crown with a yellowish-cream tint, and bright pink prominences flash at the very edge of the disk. One of them flew unusually far from the edge of the moon. Diverging to the sides, the rays of the crown gradually turn pale and merge with the dark blue background of the sky. The effect of presence is such that I am not standing on the sand, but flying in the sky. And time seemed to disappear...

Suddenly, a bright light hit my eyes - it was the edge of the Sun that floated out from behind the Moon. How quickly it all ended! Prominences and rays of the corona are visible for a few more seconds, and the shooting continues until the last. The program is done! A few minutes later, the day flares up again. The birds immediately forgot the fright from the extraordinary fleeting night. But for many years my memory has kept a feeling of the absolute beauty and grandeur of the cosmos, a feeling of belonging to its mysteries.

How was the speed of light measured for the first time?

Eclipses occur not only in the Sun-Earth-Moon system. For example, the four largest moons of Jupiter, discovered by Galileo Galilei in 1610, played an important role in the development of navigation. In that era, when there were no accurate marine chronometers, it was possible to find out the Greenwich time, which was necessary to determine the longitude of the ship, far from their native shores. Eclipses of satellites in the Jupiter system occur almost every night, when one or the other satellite enters the shadow cast by Jupiter, or hides from our view behind the disk of the planet itself. Knowing the pre-calculated moments of these phenomena from the marine almanac and comparing them with the local time obtained from elementary astronomical observations, one can determine one's longitude. In 1676, the Danish astronomer Ole Christensen Römer noticed that the eclipses of Jupiter's moons deviated slightly from the predicted moments. The Jupiter clock either went ahead by a little over eight minutes, then, after about six months, it lagged behind by the same amount. Roemer compared these fluctuations with the position of Jupiter relative to the Earth and came to the conclusion that the whole thing is in the delay in the propagation of light: when the Earth is closer to Jupiter, eclipses of its satellites are observed earlier, when further away, later. The difference, which was 16.6 minutes, corresponded to the time for which the light traveled the diameter of the earth's orbit. So Roemer measured the speed of light for the first time.

Encounters in Heavenly Knots

By an amazing coincidence, the apparent sizes of the Moon and the Sun are almost the same. Thanks to this, in rare minutes of total solar eclipses, you can see prominences and the solar corona - the outermost plasma structures of the solar atmosphere, constantly “flying away” into outer space. If the Earth had not had such a large satellite, for the time being, no one would have guessed about their existence.

The visible paths across the sky of the Sun and the Moon intersect at two points - the nodes through which the Sun passes about once every six months. It is at this time that eclipses become possible. When the Moon meets the Sun at one of the nodes, a solar eclipse occurs: the top of the cone of the lunar shadow, resting against the surface of the Earth, forms an oval shadow spot, which moves at high speed along the earth's surface. Only people who get into it will see the lunar disk, completely covering the sun. For an observer of the total phase band, the eclipse will be partial. Moreover, in the distance it may not even be noticed - after all, when less than 80-90% of the solar disk is covered, the decrease in illumination is almost imperceptible to the eye.

The width of the total phase band depends on the distance to the Moon, which, due to the ellipticity of its orbit, varies from 363 to 405 thousand kilometers. At the maximum distance, the cone of the lunar shadow does not reach the surface of the Earth a little. In this case, the visible dimensions of the Moon turn out to be slightly smaller than the Sun, and instead of a total eclipse, an annular eclipse occurs: even in the maximum phase, a bright rim of the solar photosphere remains around the Moon, which makes it difficult to see the corona. Astronomers, of course, are primarily interested in total eclipses, in which the sky darkens so much that a radiant corona can be observed.

Lunar eclipses (from the point of view of a hypothetical observer on the Moon they would, of course, be solar) occur during a full moon when our natural satellite passes the node opposite to where the Sun is and enters the cone of shadow cast by the Earth. There is no direct sunlight inside the shadow, but the light refracted in the earth's atmosphere still hits the moon's surface. It usually paints it in a reddish (and sometimes brown-greenish) color due to the fact that in the air long-wave (red) radiation is absorbed less than short-wave (blue). One can imagine what horror the suddenly darkened, ominously red disk of the Moon inspired in primitive man! What can we say about solar eclipses, when the daylight, the main deity for many peoples, suddenly began to disappear from the sky?

It is not surprising that the search for patterns in the order of eclipses became one of the first difficult astronomical tasks. Assyrian cuneiform tablets dating back to 1400-900 BC. e., contain data on systematic observations of eclipses in the era of the Babylonian kings, as well as a mention of a remarkable period of 65851/3 days (saros), during which a sequence of lunar and solar eclipses is repeated. The Greeks went even further - according to the shape of the shadow creeping on the Moon, they concluded that the Earth is spherical and that the Sun is much larger than it.

How masses of other stars are determined

Alexander Sergeev

Six hundred "sources"

With distance from the Sun, the outer corona gradually fades. Where in the photographs it merges with the sky background, its brightness is a million times less than the brightness of the prominences and the inner corona surrounding them. At first glance, it is impossible to photograph the corona along its entire length from the edge of the solar disk to merging with the sky background, because it is well known that the dynamic range of photographic matrices and emulsions is thousands of times smaller. But the pictures that this article illustrates prove otherwise. The problem has a solution! Only you need to go to the result not straight ahead, but around: instead of one “ideal” frame, you need to take a series of shots with different exposures. Different images will reveal regions of the corona at different distances from the Sun.

Such images are first processed separately, and then combined with each other according to the details of the rays of the corona (images cannot be combined along the Moon, because it is moving rapidly relative to the Sun). Digital photo processing is not as easy as it seems. However, our experience shows that any images of one eclipse can be brought together. Wide-angle with telephoto, short and long exposure, professional and amateur. In these pictures, there are pieces of the work of twenty-five observers who photographed the eclipse of 2006 in Turkey, the Caucasus and Astrakhan.

Six hundred original images, having undergone many transformations, turned into just a few separate images, but what! Now they have all the smallest details of the corona and prominences, the chromosphere of the Sun and stars up to the ninth magnitude. Such stars, even at night, are only visible through good binoculars. The rays of the corona "worked" up to a record 13 radii of the solar disk. And more color! Everything that is visible in the final images has a real color that matches the visual sensations. And this was achieved not by artificial coloring in Photoshop, but by using strict mathematical procedures in the processing program. The size of each image approaches a gigabyte - you can make prints up to one and a half meters wide without any loss of detail.

How to refine the orbits of asteroids

Eclipsing variable stars are close binary systems in which two stars revolve around a common center of mass so that the orbit is turned edge-on towards us. Then the two stars regularly outshine each other, and the earthly observer sees periodic changes in their total brightness. The most famous eclipsing variable star is Algol (beta Perseus). The circulation period in this system is 2 days 20 hours and 49 minutes. During this time, two minima are observed on the light curve. One deep, when the small but hot white star Algol A is completely hidden behind the dim red giant Algol B. At this time, the total brightness of the binary star drops by almost 3 times. A less noticeable decrease in brightness, by 5–6%, is observed when Algol A passes against the background of Algol B and slightly weakens its brightness. A careful study of the light curve reveals a lot of important information about the star system: the size and luminosity of each of the two stars, the degree of elongation of their orbit, the deviation of the shape of stars from spherical under the action of tidal forces, and most importantly, the masses of stars. Without this information, it would be difficult to create and test a modern theory of the structure and evolution of stars. Stars can be eclipsed not only by stars, but also by planets. When the planet Venus passed across the disk of the Sun on June 8, 2004, few people thought of talking about an eclipse, since the tiny dark speck of Venus had almost no effect on the brilliance of the Sun. But if a gas giant like Jupiter were to take its place, it would obscure about 1% of the area of ​​the solar disk and reduce its brightness by the same amount. This can already be registered with modern instruments, and today there are already cases of such observations. And some of them are made by amateur astronomers. In fact, "exoplanetary" eclipses are the only way available to amateurs to observe planets around other stars.

Alexander Sergeev

Panorama in the moonlight

The extraordinary beauty of a solar eclipse is not limited to the sparkling crown. After all, there is also a glowing ring along the entire horizon, which creates a unique illumination at the moment of the full phase, as if the sunset occurs from all sides of the world at once. But few people manage to take their eyes off the crown and look at the amazing colors of the sea and mountains. This is where panoramic photography comes in. Several shots joined together will show everything that escaped the eye or did not cut into memory.

The panoramic shot in this article is special. Its horizontal coverage is 340 degrees (almost a full circle), and vertically almost to the zenith. Only on it we later examined cirrus clouds, which almost spoiled our observations - they are always a change in the weather. And indeed, the rain began within an hour after the Moon descended from the disk of the Sun. The contrails of the two planes visible in the picture do not actually break off in the sky, but simply go into the moon's shadow and become invisible because of this. On the right side of the panorama, the eclipse is in full swing, and on the left side of the image, the full phase has just ended.

To the right and below the crown is Mercury - it never goes far from the Sun, and not everyone can see it. Even lower sparkles Venus, and on the other side of the Sun - Mars. All the planets are located along one line - the ecliptic - the projection onto the sky of the plane, near which all the planets revolve. Only during an eclipse (and also from space) is it possible to see our planetary system surrounding the Sun from an edge like this. In the central part of the panorama, the constellations Orion and Auriga are visible. The bright stars Capella and Rigel are white, while the red supergiant Betelgeuse and Mars are orange (the color is visible when magnified). Hundreds of people who watched the eclipse in March 2006 now feel like they saw it all with their own eyes. But the panoramic shot helped them - it is already posted on the Internet.

How should you take pictures?

On March 29, 2006, in the village of Kemer on the Mediterranean coast of Turkey, in anticipation of the beginning of a total eclipse, experienced observers shared secrets with beginners. The most important thing at an eclipse is not to forget to open the lenses. This is not a joke, this really happens. And you should not duplicate each other, making the same frames. Let everyone shoot what exactly with his equipment can turn out better than others. For observers armed with wide-angle cameras, the main target is the outer corona. We must try to take a series of pictures of her with different shutter speeds. Telephoto owners can get detailed images of the middle corona. And if you have a telescope, then you need to photograph the area at the very edge of the lunar disk and not waste precious seconds working with other equipment. And the call was then heard. And immediately after the eclipse, observers began to freely exchange files with images in order to assemble a set for further processing. This later led to the creation of a bank of original images from the 2006 eclipse. Everyone now understood that from the original images to a detailed image of the entire crown is still very, very far away. The times when any sharp picture of an eclipse was considered a masterpiece and the final result of observations are irrevocably gone. Upon returning home, everyone was waiting for work at the computer.

active sun

The Sun, like other stars similar to it, is distinguished by periodically occurring states of activity, when many unstable structures arise in its atmosphere as a result of complex interactions of a moving plasma with magnetic fields. First of all, these are sunspots, where part of the thermal energy of the plasma is converted into the energy of the magnetic field and into the kinetic energy of the movement of individual plasma flows. Sunspots are cooler than their surroundings and appear darker against the background of the brighter photosphere, the layer of the Sun's atmosphere from which most of our visible light comes. Around the spots and throughout the active region, the atmosphere, additionally heated by the energy of damped magnetic fields, becomes brighter, and structures called torches (visible in white light) and flocculi (observed in monochromatic light of individual spectral lines, for example, hydrogen) appear.

Above the photosphere are more rarefied layers of the solar atmosphere 10-20 thousand kilometers thick, called the chromosphere, and above it the corona extends for many millions of kilometers. Above groups of sunspots, and sometimes even aside from them, extended clouds often appear - prominences, which are clearly visible during the total phase of the eclipse on the edge of the solar disk in the form of bright pink arcs and emissions. The corona is the rarefied and very hot part of the Sun's atmosphere, which seems to evaporate into the surrounding space, forming a continuous stream of plasma moving away from the Sun, called the solar wind. It is he who gives the solar corona a radiant appearance that justifies its name.

From the motion of matter in the tails of comets, it turned out that the speed of the solar wind gradually increases with distance from the Sun. Moving away from the sun by one astronomical unit (the radius of the earth's orbit), the solar wind "flies" at a speed of 300-400 km / s at a particle concentration of 1-10 protons per cubic centimeter. Encountering obstacles in the form of planetary magnetospheres on its way, the solar wind flow forms shock waves that affect the atmospheres of planets and the interplanetary medium. By observing the solar corona, we obtain information about the state of space weather in outer space around us.

The most powerful manifestations of solar activity are plasma explosions called solar flares. They are accompanied by strong ionizing radiation, as well as powerful ejections of hot plasma. Passing through the corona, plasma flows noticeably affect its structure. For example, helmet-shaped formations are formed in it, turning into long rays. In fact, these are elongated tubes of magnetic fields, along which streams of charged particles propagate at high speeds (mainly energetic protons and electrons). In fact, the visible structure of the solar corona reflects the intensity, composition, structure, direction of movement and other characteristics of the solar wind, which constantly affects our Earth. During flashes, its speed can reach 600-700, and sometimes more than 1000 km/s.

In the past, the corona was observed only during total solar eclipses and only near the Sun. In total, about an hour of observations accumulated. With the invention of the non-eclipsing coronagraph (a special telescope in which an artificial eclipse is arranged), it became possible to constantly monitor the inner regions of the corona from the Earth. It is also always possible to register the radio emission of the corona, even through clouds and at great distances from the Sun. But in the optical range, the outer regions of the corona are still visible from the Earth only in the total phase of a solar eclipse.

With the development of extra-atmospheric research methods, it became possible to directly image the entire corona in ultraviolet and x-rays. The most impressive images regularly come from the space-based SOHO Solar Orbital Heliospheric Observatory, launched in late 1995 by the joint efforts of the European Space Agency and NASA. In the SOHO images, the rays of the corona are very long, and many stars are visible. However, in the middle, in the region of the inner and middle crown, the image is missing. The artificial "moon" in the coronograph is too big and obscures much more than the real one. But it is impossible otherwise - the Sun shines too brightly. So satellite imagery does not replace observations from Earth. But space and terrestrial images of the solar corona complement each other perfectly.

SOHO also constantly monitors the surface of the Sun, and eclipses are not a hindrance to it, because the observatory is located outside the Earth-Moon system. Several ultraviolet images taken by SOHO around the total phase of the 2006 eclipse have been pieced together and placed in place of the image of the Moon. Now we can see which active regions in the atmosphere of the star closest to us are associated with certain features in its corona. It may seem that some "domes" and zones of turbulence in the corona are not caused by anything, but in reality their sources are simply hidden from observation on the other side of the star.

"Russian" eclipse

The next total solar eclipse is already being called “Russian” in the world, since it will be mainly observed in our country. On the afternoon of August 1, 2008, the full phase band will stretch from the Arctic Ocean almost along the meridian to Altai, passing exactly through Nizhnevartovsk, Novosibirsk, Barnaul, Biysk and Gorno-Altaisk - right along the federal highway M52. By the way, this will be the second eclipse in Gorno-Altaisk in a little over two years - it is in this city that the eclipse bands of 2006 and 2008 intersect. During the eclipse, the Sun's height above the horizon will be 30 degrees, which is enough to photograph the corona and ideal for panoramic shooting. The weather in Siberia at this time is usually good. It's not too late to get a couple of cameras ready and buy a plane ticket.

This eclipse is not to be missed. The next total eclipse will be visible in China in 2009, and then good conditions for observations will be formed only in the USA in 2017 and 2024. In Russia, the break will last almost half a century - until April 20, 2061.

If you're going, then here's to you good advice: observe in groups and share the received images, send them for joint processing to the Flower Observatory: www.skygarden.ru. Then someone will definitely be lucky with the processing, and then everyone, even those who stay at home, thanks to you, will see the eclipse of the Sun - a star crowned with a crown.

Already this Saturday, August 11, 2018, a new mission to study the Sun - the Parker Solar Probe (or the Parker solar probe) will go into space. In a few years, the device will come closer to the Sun than any man-made object has yet managed to do. Editorial N+1 With the help of Sergei Bogachev, chief researcher at the Laboratory of X-ray Solar Astronomy at the Lebedev Physical Institute, she decided to find out why scientists send the device to such a hot place and what results are expected from it.

When we look at the night sky, we see a huge number of stars - the most numerous category of objects in the universe that can be observed from Earth. It is these huge shining gas balls that produce in their thermonuclear "furnaces" many chemical elements heavier than hydrogen and helium, without which our planet, and all life on it, and ourselves would not exist.

The stars are at great distances from the Earth - the distance to the nearest of them, Proxima Centauri, is estimated at several light years. But there is one star whose light takes only eight minutes to reach us - this is our Sun, and observing it helps us learn more about other stars in the Universe.

The sun is much closer to us than it seems at first glance. In a certain sense, the Earth is inside the Sun - it is constantly washed by the flow of the solar wind coming from the corona - the outer part of the star's atmosphere. It is the streams of particles and radiation from the Sun that control the "space weather" near the planets. The emergence of auroras and disturbances in planetary magnetospheres depends on these streams, while solar flares and coronal mass ejections disable satellites, affect the evolution of life forms on Earth, and determine the radiation load on manned space missions. Moreover, similar processes occur not only in the solar system, but also in other planetary systems. Therefore, understanding the processes in the solar corona and the inner heliosphere allows us to better navigate the behavior of the plasma "ocean" surrounding the Earth.

Structure of the Sun

Wikimedia Commons

“Due to the remoteness of the Sun, we receive almost all information about it through the radiation it generates. Even some simple parameters, such as temperature, which on Earth can be measured with an ordinary thermometer, for the Sun and stars are determined in a much more complicated way - by the spectrum of their radiation. This also applies to more complex characteristics, such as the magnetic field. The magnetic field is able to influence the radiation spectrum, splitting the lines in it - this is the so-called Zeeman effect. And it is precisely due to the fact that the field changes the radiation spectrum of the star that we are able to register it. If such an influence did not exist in nature, then we would not know anything about the magnetic field of stars, since there is no way to directly fly up to a star, ”says Sergey Bogachev.

“But this method also has limitations - take at least the fact that the absence of radiation deprives us of information. If we talk about the Sun, then the solar wind does not emit light, so there is no way to remotely determine its temperature, density and other properties. Does not emit light or magnetic field. Yes, in the lower layers of the solar atmosphere magnetic tubes are filled with luminous plasma and this makes it possible to measure the magnetic field near the surface of the Sun. However, already at a distance of one solar radius from its surface, such measurements are impossible. And there are many such examples. How to be in such a situation? The answer is very simple: you need to launch probes that can fly directly to the Sun, plunge into its atmosphere and into the solar wind, and take measurements directly on the spot. Such projects are widespread, though less known than those of space telescopes, which make remote observations and provide much more spectacular data (such as photographs) than probes that produce boring streams of numbers and graphs. But if we talk about science, then, of course, few remote observations can be compared in strength and persuasiveness with the study of an object that is located nearby, ”continues Bogachev.

Mysteries of the Sun

Observations of the Sun have been made since Ancient Greece and in Ancient Egypt, and over the past 70 years, more than a dozen space satellites, interplanetary stations and telescopes, ranging from Sputnik-2 to space observatories operating today, such as SDO, SOHO or STEREO, have been closely watched (and are watching) behind the behavior of the star closest to us and its environs. Nevertheless, astronomers still have many questions related to the structure of the Sun and its dynamics.

For example, for more than 30 years, scientists have been facing the problem of solar neutrinos, which consists in the lack of registered electron neutrinos produced in the core of the Sun as a result of nuclear reactions, compared with their theoretically predicted number. Another mystery is related to the anomalous heating of the corona. This outermost layer of the star's atmosphere has a temperature of more than a million degrees Kelvin, while the visible surface of the Sun (the photosphere), above which the chromosphere and corona are located, is heated to only six thousand degrees Kelvin. This seems strange, because logically, the outer layers of the star should be colder. Direct heat transfer between the photosphere and the corona is not enough to provide these temperatures, which means that other coronal heating mechanisms are at work here.

The corona of the Sun during the total solar eclipse in August 2017.

NASA's Goddard Space Flight Center/Gopalswamy

There are two main theories to explain this anomaly. According to the first one, magnetoacoustic waves and Alfven waves are responsible for heat transfer from the convective zone and photosphere of the Sun to the chromosphere and corona, which, being scattered in the corona, increase the plasma temperature. However, this version has a number of disadvantages, for example, magnetoacoustic waves cannot ensure the transfer of a sufficiently large amount of energy to the corona due to scattering and reflection back to the photosphere, and Alfven waves relatively slowly convert their energy into thermal energy plasma. In addition, for a long time there was simply no direct evidence of wave propagation through the solar corona - it was not until 1997 that the SOHO space observatory first recorded magnetoacoustic solar waves at a frequency of one millihertz, which provide only ten percent of the energy needed to heat the corona to the observed temperatures.

The second theory relates the anomalous heating of the corona to constantly occurring microflares arising from the continuous reconnection of magnetic lines in local regions of the magnetic field in the photosphere. This idea was proposed in the 1980s by the American astronomer Eugene Parker, whose name is the probe and who also predicted the presence of the solar wind, a stream of high-energy charged particles continuously emitted by the Sun. However, the theory of microoutbursts has not yet been confirmed either. It is possible that both mechanisms work on the Sun, but this needs to be proven, and for this it is necessary to fly up to the Sun at a fairly close distance.

Another secret of the Sun is connected with the corona - the mechanism of the formation of the solar wind that fills the entire solar system. It is on him that such phenomena of space weather as the northern lights or magnetic storms depend. Astronomers are interested in the mechanisms of origin and acceleration of the slow solar wind, born in the corona, as well as the role of magnetic fields in these processes. Here too, there are several theories with both evidence and flaws, and it is expected that the Parker probe will help to dot the i's.

“In general, at present, there are sufficiently developed models of the solar wind that predict how its characteristics should change as it moves away from the Sun. The accuracy of these models is quite high at distances of the order of the Earth's orbit, but it is not clear how accurately they describe the solar wind at close distances from the Sun. Perhaps Parker can help with that. Another rather interesting question is the acceleration of particles on the Sun. After flares, streams of a large number of accelerated electrons and protons come to the Earth. It is not completely clear, however, whether their acceleration occurs directly on the Sun, and then they simply move towards the Earth by inertia, or whether these particles are additionally (and maybe completely) accelerated on their way to the Earth by interplanetary magnetic field. Perhaps, when data collected by a probe near the Sun arrives on Earth, this issue can also be dealt with. There are several other similar problems that can be solved in the same way - by comparing similar measurements near the Sun and at the level of the Earth's orbit. In general, the mission is aimed at solving such issues. We can only hope that the device will be successful,” says Sergey Bogachev.

Straight into hell

The Parker probe will be launched on August 11, 2018 from the launch complex SLC-37 at Cape Canaveral Air Force Base, it will be launched into space by a heavy launch vehicle Delta IV Heavy - this is the most powerful rocket in operation, it can launch into low orbit almost 29 tons of cargo. In terms of carrying capacity, it is surpassed only by, but this carrier is still in the testing stage. To get to the center of the solar system, it is necessary to extinguish the very high speed that the Earth (and all objects on it) has relative to the Sun - about 30 kilometers per second. In addition to a powerful rocket, this will require a series of gravitational maneuvers near Venus.

According to the plan, the process of approaching the Sun will last seven years - with each new orbit (there are 24 in total), the device will come closer to the star. The first perihelion will be passed on November 1, at a distance of 35 solar radii (about 24 million kilometers) from the star. Then, after a series of seven gravitational maneuvers near Venus, the device will approach the Sun to a distance of about 9-10 solar radii (about six million kilometers) - this will happen in mid-December 2024. This is seven times closer than the perihelion of Mercury's orbit, no man-made spacecraft has ever gotten so close to the Sun (the current record belongs to the Helios-B apparatus, which approached the star at 43.5 million kilometers).

Scheme of the flight to the Sun and the main working orbits of the probe.

The main stages of work on each of the orbits.

The choice of such a position for observations is not accidental. According to the calculations of scientists, at a distance of ten radii from the Sun is the Alfven point - the region where the solar wind accelerates so much that it leaves the Sun, and the waves propagating in the plasma no longer affect it. If the probe can be near the Alfven point, then we can assume that it entered the solar atmosphere and touched the Sun.

Probe "Parker" in the assembled state, during installation on the third stage of the launch vehicle.

"The mission of the probe is to measure the main characteristics of the solar wind and the solar atmosphere along its trajectory. The scientific instruments on board are not unique, they do not have record characteristics (except for the ability to withstand solar radiation fluxes at the perihelion of the orbit). The Parker Solar Probe is a spacecraft with conventional instruments, but in a unique orbit.Most (perhaps even all scientific instruments) are planned to be kept off at all parts of the orbit except perihelion, where the spacecraft is closest to the Sun.In a sense, such a science program further emphasizes that the main the task of the mission is to study the solar wind and the solar atmosphere.When the device moves away from perihelion, the data from the same instruments will turn into ordinary ones, and in order to save the resource of scientific instruments, they will simply be switched to the background until the next approach.In this sense, the ability to reach a given trajectory and the ability to to come to life on it for a given time - these are the factors on which the success of the mission will primarily depend,” says Sergey Bogachev.

The device of the heat shield "Parker".

Greg Stanley/Johns Hopkins University

View of the heat shield at the stage of installation on the probe.

NASA/Johns Hopkins APL/Ed Whitman

Probe "Parker" with installed heat shield.

NASA/Johns Hopkins APL/Ed Whitman

To survive near the star, the probe is equipped with a heat shield that acts as an "umbrella" under which all scientific instruments will hide. The front of the shield will withstand temperatures in excess of 1,400 degrees Celsius, while the back of the shield, where the scientific instruments are located, must not exceed thirty degrees Celsius. Such a temperature difference is provided by the special design of this "solar umbrella". With a total thickness of just 11.5 centimeters, it consists of two panels made of carbon-graphite composite, between which there is a layer of carbon foam. The front of the shield has a protective coating and a white ceramic layer that increases its reflective properties.

In addition to the shield, the cooling system is designed to solve the problem of overheating, using 3.7 liters of pressurized deionized water as a coolant. electrical wiring The device is made using high-temperature materials such as sapphire tubes and niobium, and during approaches to the Sun, the solar panels will be removed under the heat shield. In addition to strong heating, mission engineers will have to take into account strong light pressure from the Sun, which will interfere with the correct orientation of the probe. To facilitate this work, the probe in different places Sunlight sensors have been installed to help control the protection of scientific equipment from the effects of the sun.

Tools

Almost all scientific instruments of the probe are "sharpened" for the study of electromagnetic fields and the properties of the solar plasma surrounding it. The only exception is the WISPR (Wide-field Imager for Solar PRobe) optical telescope, whose task will be to obtain images of the solar corona and solar wind, the inner heliosphere, shock waves, and any other structures observed by the apparatus.

The corona makes up the outer atmosphere of the Sun, passing in its outermost parts into the interplanetary medium. Outwardly, it looks like a silver and pearl radiance around the Sun. There are many details in it - rays, feathers, fans, arches, etc. During the years of maximum sunspots, the corona surrounds the entire Sun in a rather symmetrical manner and has a generally "disheveled" appearance (Fig. 27). During sunspot minimum years, it is compressed at the poles and extended along the equator (Fig. 28). Thus, to a certain extent, the corona is a product of solar activity.

The solar corona, where it touches the chromosphere, is incomparably brighter than, say, at a distance of 10-12 from the solar edge, and further on its brightness continues to decrease with height, but very slowly, so that it can be traced on good photos up to distances from the edge of the Sun reaching several solar radii.

(click to view scan)

The limit here is the brightness of the sky background, reaching a high level even during very long eclipses. Photographs taken during eclipses from high mountains and high-altitude aircraft show the corona extending a dozen or more degrees from the Sun, where the corona imperceptibly merges with the phenomenon of zodiacal light (see chapter IX, § 39). The integral brightness of the corona is only one millionth of the brightness of the Sun (from to). Even its brightest parts were previously inaccessible to observations outside of eclipses.

Rice. 29. Fine structure of the inner crown. The photograph was taken outside the eclipse with a Lyot coronagraph in the light of the green coronal line

In spectral terms, the solar corona contains three components: L, K and F, L is an emission component consisting of two to three dozen bright lines extending to a height of about 9. These lines are visible against the background of the K-component - a continuous spectrum. At a height of about 3 from the edge of the Sun, a small amount of the F component, i.e., the Fraunhofer spectrum, qualitatively no different from the spectrum of the solar photosphere, begins to be mixed into the K spectrum. The F-spectrum is very clearly visible already at height 10, where the L-spectrum ends, and this height is considered the boundary of the inner corona (Fig. 29). Above lies the outer corona, whose spectrum at a height of 20 and more consists mainly of the F component. The integrated brightness of the F component is about the brightness of the Sun.

The light from the inner corona is markedly polarized. After a height of 10 above the edge, the polarization, reaching a value of about 45%, rapidly decreases.

We can assume that the K-component is polarized, while the F-component is not. The polarization is such that the electric vector of the polarized component of light is perpendicular to the radius vector (in the picture plane) emanating from the center of the Sun.

The duration of observations of the solar corona during an eclipse along the entire band of the total phase is usually 2-3 hours. During this time, only the most insignificant movements are detected in the corona. But if the corona is systematically observed outside of eclipses on a Lyo coronograph, it is not difficult to notice changes in the corona from one day to the next. The repetition of the shape of the isophotes of the L-corona in the light of one or another line, as well as a steadily repeating increase in its radiation approximately two weeks later (the isophotes that were on one edge are transferred to the other edge of the Sun) and after four weeks (the isophotes are repeated on this edge) made it possible establish with complete certainty the fact of rotation of the corona and find the period of its rotation - it coincided with the period of rotation of the Sun, derived from sunspots and torches. Coronal formations, spots and plumes are inextricably linked.

Earthly life owes its origin to the heavenly body. It warms and illuminates everything on the surface of our planet. No wonder the worship of the Sun and its representation as a great heavenly god was reflected in the cults of the primitive peoples who inhabited the Earth.

Centuries, millennia have passed, but its importance in human life has only increased. We are all children of the Sun.

What is the Sun?

A star from the Milky Way Galaxy, with its geometric shape, representing a huge, hot, gaseous ball, constantly radiating energy flows. The only source of light and heat in our star-planetary system. Now the Sun is in the age of a yellow dwarf, according to the generally accepted classification of the types of stars in the universe.

Characteristics of the Sun

The sun has the following properties:

• Age -4.57 billion years;
• Distance to Earth: 149,600,000 km
• Mass: 332,982 Earth masses (1.9891 10³⁰ kg);
• The average density is 1.41 g / cm³ (it increases 100 times from the periphery to the center);
• The orbital speed of the Sun is 217 km/s;
• Rotation speed: 1.997 km/s
• Radius: 695-696 thousand km;
• Temperature: from 5,778 K on the surface to 15,700,000 K in the core;
• Corona temperature: ~1,500,000 K;
• The sun is stable in its brightness, it is located in 15% of the brightest stars in our Galaxy. It emits less ultraviolet rays, but has a greater mass compared to similar stars.

What is the sun made of?

In my own way chemical composition our star is no different from other stars and contains: 74.5% hydrogen (by mass), 24.6% helium, less than 1% other substances (nitrogen, oxygen, carbon, nickel, iron, silicon, chromium, magnesium and others). Inside the nucleus, there are continuous nuclear reactions that turn hydrogen into helium. The vast majority of the mass of the solar system - 99.87% belongs to the Sun.