The amazing processes occurring on the Sun have their source in its internal energy. The same can be said about other suns - distant stars. The quiet radiance of the stars that caresses our gaze and the dazzling brilliance of the Sun have the same nature, the same origin.
To people far from modern astronomy, it may seem that the glow of stars, including the Sun, can be explained simply. All these cosmic bodies are unusually hot, so it is not surprising that they emit powerful streams of light.
The simplicity of this explanation is only apparent. It leaves the main thing unclear: what exactly makes stars be the hottest of all celestial bodies and why their temperature, as a rule, remains practically unchanged for enormous periods of time.
In search of an answer to these questions, various assumptions have been made. They first tried to assume that the glow of the Sun was caused by its combustion. This well-known word refers to the process of combining molecules of a burning substance with oxygen molecules, as a result of which heat is released and more complex molecules are formed.
It is easy to understand that the Sun cannot burn. Firstly, there is no oxygen in the airless space surrounding the Sun. Secondly, at the temperatures existing on the Sun, molecular compounds are not formed, as during combustion, but, on the contrary, decompose into atoms. Finally, thirdly, if the Sun consisted entirely of the best coal, then even in this case it would completely “burn out” in a few thousand years. Meanwhile, the age of the Earth is measured in several billion years and, as facts prove, during all this time the Sun shone almost the same as it does now. This means that the lifespan of the Sun and stars, that is, in other words, the duration of their glow, is measured in tens, and maybe hundreds of billions of years.
At one time it was thought that the Sun was continuously heated by meteorites falling on its surface. Calculations have shown that in this case only the surface layers of the Sun would be heated, and its interior would remain cold. And the energy released would be incomparably less than observed. In addition, meteorites falling on the Sun would quickly increase its mass, which, however, is not noticed.
We had to reject the hypothesis of the compression of the Sun. Its supporters argued that the ball of gas, called the Sun, is continuously compressed, and when compressed, the gases heat up. But, as calculations show, the heat released during compression is not enough to explain the lifespan of the Sun and stars. Even if the Sun was initially infinitely large, then, releasing the observed energy, it should have contracted to its present state in just twelve million years. To recognize the Sun as so young means to ignore the facts.
True, as it turned out recently, at some stages of a star’s development, compression can play the role of the main source of energy. This is how very young and very old stars apparently maintain their lives.
At the end of the last century, radioactivity was discovered. It turned out that the radioactive decay of uranium, radium and other substances releases a significant amount of energy. For the first time, humanity became acquainted with the power of atomic energy and it is natural that some astrophysicists tried to explain the mystery of the glow of the Sun and stars by radioactive processes.
Atoms of uranium and radium decay extremely slowly.
It takes four and a half billion years for half a given number of uranium atoms to decay, and one thousand five hundred and ninety years for radium. Therefore, when decaying, uranium and radium release very little energy per unit time. If the Sun consisted entirely of uranium, then even in this case the “uranium” sun would shine much weaker than the real one.
There are radioactive elements that decay very quickly - within days, hours or even minutes. But these elements are not suitable as sources of energy for the Sun and stars for other reasons: they do not explain the extraordinary life span of cosmic bodies.
But still, the “radioactive” hypothesis brought benefits to science. She convinced astrophysicists that only atomic energy could be the cause of the glow of the Sun and stars.
The depths of the Sun are hidden from our eyes. Despite this, some completely reliable statements can be made about the state of the solar interior.
The temperature of a gas, as is known, is inextricably linked with its pressure. By compressing a gas, we increase its temperature, and if the compression is very high, then the temperature of the gas becomes very high.
This is exactly what happens in the depths of the Sun. The central parts of the solar globe are pressed with colossal force by its overlying layers. This force is opposed by the elasticity of the gas, expressing its desire for unlimited expansion.
At each point inside the Sun, the elasticity, or, in other words, the pressure of the internal mass of gases, is balanced by the heaviness or weight of the overlying gas layers. Each such equilibrium state corresponds to a certain gas temperature, calculated using relatively simple formulas. With their help, the undoubted conclusion was reached that the monstrous pressure in the central regions of the Sun corresponds to a temperature of 15 million degrees!
If it were possible to extract a piece of matter the size of a pinhead from the depths of the sun, then this tiny piece of the Sun would emit such heat that it would instantly incinerate all life around it within a radius of many kilometers! Perhaps this example will give the reader at least a partial sense of what a temperature of 15 million degrees is.
In the depths of the Sun there reigns an unimaginable “crush” of moving atoms. They are unable to fully preserve their electronic “clothing”. During mutual collisions, as well as when they hit powerful “portions” of light - quanta - atoms lose part of their electrons and continue to randomly “push” in a very “naked” form.
When a person takes off his clothes, his external dimensions hardly change. Something else happens during the destruction, or, as they say, ionization, of atoms. Electron shells occupy a huge amount of space compared to the atomic nucleus, and having lost its electronic “clothing”, the atom greatly decreases in size. It is natural, therefore, that a gas consisting of ionized atoms can be compressed much more strongly than a gas made of undestroyed, neutral atoms. It follows that the gases at the center of the Sun are not only very hot, but also unusually dense.
The pressure in the central regions of the Sun reaches several billion atmospheres, and therefore a grain of matter extracted from the depths of the Sun would be five times denser than platinum!
A gas denser than steel. Doesn't this sound absurd? But unusual quantities (colossal pressures) also give rise to a quality unusual in earthly conditions.
The substance of the solar interior, with all its extraordinary density, still remains a gas. The difference between solids and gases is not density at all, but something else. Gas has elasticity: compressed to a certain volume, it will then strive to expand again and will certainly do this if external forces do not interfere with it. Solids behave differently. A strongly compressed solid body (for example, a piece of lead) after removing the load will remain in a deformed, altered state. This is the main difference between solids and gases.
Despite the high, seemingly fantastic, density, the gases in the depths of the Sun do not lose their elasticity. They, as studies of other stars show, can be compressed even more and, of course, freed from the pressure of the outer layers of the Sun, they would immediately expand. This means that the substance of the solar interior can be considered a gas.
The processes taking place in the depths of the Sun are unlike what we see around us on Earth. At a temperature of 15 million degrees, atomic energy is released from matter almost as easily as steam is released from water at its boiling point.
In various ways it has been established that the Sun consists of half hydrogen and 40 percent helium with a very small “admixture” of other elements. In the depths of the Sun, hydrogen turns or, as it were, “burns out” into helium. Processes in which the composition of atomic nuclei changes are called nuclear reactions.
It is hardly worth boring the reader with a detailed examination of all those nuclear reactions as a result of which hydrogen in the depths of the Sun gradually turns into helium. For those interested in this issue, we recommend reading the book by A. G. Masevich. Let us only point out the main thing - in the process of nuclear reactions, one type of matter (substance) turns into another (light) while preserving both mass and energy.
To form the nucleus of a helium atom, four protons are needed, that is, four nuclei of a hydrogen atom. Two of these protons lose their positive charge as a result of nuclear reactions and turn into neutrons. But two protons and two neutrons taken individually weigh 4.7 x 10 -26 grams more than a helium nucleus. This excess, or “mass defect,” is converted into radiation, and the energy released in this case is equal to 4·10 -5 erg.
Don't think that this is very little. After all, we are talking about the formation, synthesis of one helium atom. If 1 gram of hydrogen is converted into helium, then the energy released is 6 × 10 18 erg. Such energy would be enough to lift a loaded freight train of fifty cars to the top of the highest mountain on earth - Chomolungma!
Every second, the Sun turns 4 million tons of its matter into radiation. This amount of substances could load four thousand trains with fifty cars each. This means that, emitting light, the Sun loses its mass and decreases in weight. While you read this phrase, the Sun will “lose weight” by 12 million tons, and within a day its mass will decrease by a third of a billion tons.
And yet this “mass leak” is practically imperceptible for the Sun. Even if the Sun always radiates light and heat as intensely as in the present era, then over its entire life (that is, over tens of billions of years) its weight will decrease by an insignificant fraction of its current mass.
The conclusion is clear: nuclear reactions converting hydrogen into helium fully explain why the Sun shines.
In addition to the transformation of hydrogen into helium, there is another nuclear reaction that may play the same, if not a greater role in the depths of the Sun. We are talking about the formation of heavy hydrogen (deuterium) from ordinary hydrogen atoms.
As is known, unlike the hydrogen atom, in which the nucleus is a proton, the deuterium atom has a nucleus consisting of a proton and a neutron. When a deuterium nucleus is synthesized from two protons (one of which turns into a neutron), the excess mass, as in the previous case, turns into radiation. Recent studies have proven that this so-called proton-proton reaction releases no less energy than the conversion of hydrogen into helium. The distribution of roles between the described nuclear reactions depends on the properties of the star and mainly on the temperature of its interior. In some stars the proton-proton reaction predominates, in others - the hydrogen-helium reaction.
Thus, the Sun lives from its own depths, as if “digesting” their contents. The energy that supports life on Earth originates in the depths of the Sun. However, one should not think that the dazzlingly bright sunlight that we admire on a fine day is the light energy that originates in the depths of the sun.
The light, or more precisely, electromagnetic radiation resulting from nuclear reactions, has much higher energy and a shorter wavelength than the sun's rays that we see. But when portions of electromagnetic radiation, called quanta, make their way from the central regions of the Sun to its surface, they are absorbed many times and then re-emitted by atoms in all sorts of directions. Therefore, the path of the ray from the center of the Sun to its surface is very complex and resembles an intricate zigzag curve.
This wandering can continue for hundreds and thousands of years before the beam breaks out onto the surface of the Sun. But he gets here very “exhausted” from continuous interactions with atoms. Having lost a significant portion of its original energy, the beam turned from invisible radiation, reminiscent of X-rays, into a dazzlingly bright sunbeam that was perfectly perceived by the eye.
The mystery of the sun's glow has been largely solved. We are now talking only about clarifying the picture of those nuclear reactions that take place in the depths of the Sun. The same can be said about many other stars that are close in nature to the Sun. But among the great diversity of the stellar world, there are also stars whose glow cannot be explained by the reactions described above. These include, for example, white dwarfs. With a mass close to that of the Sun, some of these stars are even smaller in size than the Earth. Therefore, the density of white dwarfs is exceptionally high - some of them are much denser than the central regions of the Sun. The source of energy for such stars is, apparently, compression under the influence of the forces of their own gravity.
It is not surprising that the light of some stars is a mystery to us. Not only the extreme distance of the stars, but also their colossal lifespan makes research very difficult. Compared to the life of stars, measured in tens of billions of years, the duration of human existence on Earth seems like an instant. And yet, in this moment we have already learned a lot about the world of stars. This is amazing!
>> Why do the stars shine?
Why do the stars glow in the sky?– description for children: why they glow brightly at night in different colors, what they are made of, surface temperature, size and age.
Let's talk about why the stars shine in a language that children can understand. This information will be useful for children and their parents.
Children admiring the night sky and seeing billions of bright lights. Agree that there is nothing more beautiful than a shining star. Of course it's worth it explain to the children that their number and brightness level depends on where you live. In cities, it is more difficult to spot bright stars due to artificial lighting that blocks the light. For the little ones It should be noted that the stars are suns like ours. If you were transported to another galaxy and looked at our Sun, it would resemble a familiar light.
To make it clear explanation for children, parents or teachers At school must tell us about the composition of the stars. To put it simply, it is a round glowing plasma. It is so hot that it is difficult for us to even imagine this temperature. The surface of a star like our Sun is cooler (5800 Kelvin) than its core (15 million Kelvin).
They have their own gravity and release some of their heat into space. differ in size. Children must remember that the larger its size, the less it exists. Ours is medium in size and has lived for millions of years.
The process of heat replenishment involves fusion. The energy has been accumulating inside the sun for millions of years, but it is unstable and constantly tries to escape. Once she manages to rise to the surface, she escapes into outer space in the form of the solar wind.
It is also worth remembering the role of the speed of light. He moves until he hits an obstacle. When we see stars, it is light located at a great distance. We can even observe a ray sent millions of years ago by a shining star. Need to explain to the children, that this is an important moment, because he had to overcome many obstacles to break through to us.
So when you look at the shining stars, you are literally seeing the past. If we could get there, we would notice that everything had changed a long time ago. Moreover, some could even die, become a white dwarf or a supernova.
So the stars shine because it is an energy source that has a huge hot core that releases energy into the Universe in the form of a light beam. Now you understand why the stars shine. Use our photos, videos, drawings and moving models online to better understand the description and characteristics of space objects.
The question of why stars glow is a childish one, but, nevertheless, it baffles a good half of adults who either forgot the school course in physics and astronomy or played truant a lot in childhood.
Explanation of star glow
Stars are essentially balls of gas, therefore, during their existence and the chemical processes occurring in them, they emit light. Unlike the moon, which simply reflects the light of the sun, stars, like our sun, glow themselves. If we talk about our sun, it is medium in size, as well as a star in age. As a rule, those stars that visually appear larger in the sky are closer, those that are barely visible are further away. There are still millions of those that are not visible to the naked eye at all. People became acquainted with them when the first telescope was invented.
A star, although it is not alive, has its own life cycle, which is why at different stages it has a different glow. When her life's journey comes to an end, she gradually turns into a red dwarf. In this case, its light is, accordingly, reddish, pulses are possible, the light seems to flicker, like the glow of an incandescent lamp during sudden changes in voltage in the network. Certain parts of it either become crusty or explode again with renewed vigor, visually forming such blinking lights.
Another reason for the difference in cross-sections of stars lies in their spectrality. It's like the length and frequency of the light rays they emit. This depends on the chemical composition of the star, as well as its size.
All stars are also different in size. But what is meant here is not how they look to us when looking at the sky in the evening or at night, but their actual sizes, which are calculated with varying degrees of accuracy by astronomers.
It must be said that the stars glow not only at night, but also during the day. It’s just that the sun illuminates the atmosphere during the daytime, we see it consisting of many layers of clouds. At night, the sun illuminates the other side of the earth and where it is dark, the atmosphere becomes transparent. This is how we see what surrounds our planet - the stars, its companion, the Moon, sometimes even meteorites, comets, even another planet of the solar system - Venus. It appears to be a large star, but its glow, like that of the Moon, is due to the fact that it reflects sunlight. Venus is visible mainly in the early evening or at dawn.
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The question of why stars glow is a childish one, but, nevertheless, it baffles a good half of adults who either forgot the school course in physics and astronomy or played truant a lot in childhood.
Explanation of star glow
Stars are essentially balls of gas, therefore, during their existence and the chemical processes occurring in them, they emit light. Unlike the moon, which simply reflects the light of the sun, stars, like our sun, glow themselves. If we talk about our sun, it is medium in size, as well as a star in age. As a rule, those stars that visually appear larger in the sky are closer, those that are barely visible are further away. There are still millions of those that are not visible to the naked eye at all. People became acquainted with them when the first telescope was invented.
A star, although it is not alive, has its own life cycle, therefore at its different stages it has different...
Stars are huge balls of gas that emit heat and light as a result of thermonuclear reactions. Our Sun is an average yellow star.
Stars form from large clouds of gas and dust called nebulae. The force of gravity causes these clouds to compress into a dense mass. In the center of the cloud, it compresses, the gas gradually becomes denser and heats up. When the temperature gets too high, a thermonuclear reaction, or fusion reaction, begins, in which the nuclei of hydrogen atoms fuse to form helium nuclei. This is how a new star is born.
Star Heat
In the center of the star, where the thermonuclear reaction occurs, the temperature reaches 10 million degrees. Astronomers classify stars by their temperature. Depending on the temperature, the color of the star changes: for a red dwarf it is only 3000 °C, and for a blue supergiant it is 20,000 °C. Stars also differ in brightness, which is why a more distant star may appear closer than a less distant one, but...
STARS are huge balls of gas that emit their own light, unlike the planets and their satellites, which glow with the reflected light of stars.
For example, moonlight is nothing more than sunlight reflected by the moon.
Another difference is that the stars appear to us to twinkle, while the light of the planets is steady and unblinking. The twinkling of stars is caused by the presence of various substances in the earth's atmosphere.
Since the times of ancient Greek astronomers, STARS have been divided into groups according to their size. The concept of “magnitude” here refers not to the true size of the stars, but to their brightness.
In addition, stars differ in their SPECTRA or, in other words, in the wavelengths of their radiation. By studying the spectrum of a particular star, astronomers learn a lot about its characteristics, temperature and even chemical composition.
Thus, STARS, like our SUN, illuminate the Universe around them, warm the planets around them, and give life. Why do they only glow at night?...
It's a cloudless night outside. As soon as we raise our heads to the sky, we can see a huge number of tiny luminous dust particles located somewhere very far away. These are stars, which can be many or few - it all depends on the weather and the location of the person.
In the distant past, humanity did not know what stars were, and therefore came up with various fables. For example, there was an opinion that these were nails containing the souls of dead people with which the sky was nailed. But for a long time there was no assumption that the sun is also a star. And really, how can this huge bright canvas, reminiscent of a hot frying pan, be associated with tiny dots above our heads?
It is simply impossible to calculate the exact number of stars. Meanwhile, it is known that there are a lot of them - millions or even billions. It is interesting that they are located at a huge distance from the Earth, which is sometimes impossible to travel even in a lifetime. The light from these...
Why do the stars shine?
Each of us at least once in our lives raised our heads on a quiet cloudless night and saw above our heads countless tiny fireflies that decorated the sky. Depending on the location of the observer and the weather, stars may appear larger or smaller. But what is a star and why does it shine?
In Antiquity, there were countless hypotheses about what stars are and why they glow. The stars were called the nails with which the sky was nailed, living beings, the souls of people. The list of all possible variations could take a very long time. Few people thought that our Sun is a star. Our ancestors did not in any way associate a huge ball, bursting with heat, with small silver stars.
In fact, the Sun is the most ordinary star; there are many such stars even in our galaxy. The entire starry sky is a myriad of analogues of the Sun, which are located from the Earth at unimaginable distances....
"Question Mark" 5/91
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ZIGUNENKO Stanislav Nikolaevich
Paradoxes of our days
Why do the stars glow?
N.A. Kozyrev was an astronomer. And naturally, he began to pick up the keys to world laws not on Earth, but in the Universe. In 1953, he came to a paradoxical conclusion: there is no source of energy in stars at all. Stars live by emitting heat and light due to the arrival of energies from outside.
It must be said that Nikolai Alexandrovich had his own reasons for such a judgment. Back in 1850, the German physicist R. Clasius formulated a postulate, which was later called the second law of thermodynamics. This is how it sounds: “Heat cannot move by itself from a colder body to a warmer one.”
The statement seems to be self-evident: everyone has seen how, say, a switched-off iron gradually becomes more and more...
Who doesn’t love to admire the most beautiful view of the starry sky at night, to look at thousands of bright and not so bright stars. Our article will tell you why the stars shine.
Stars are cosmic objects that emit enormous amounts of heat energy. Such a large release of heat energy is, of course, accompanied by strong light radiation. We can observe the light that has reached us.
When you look at the starry sky, you may notice that most of the stars are different. Some stars shine with their former glory, others with blue light. There are also stars that shine orange. Stars are large balls of very hot gases. Because they are heated differently, they have different glow colors. So, the hottest ones shine with blue light. Stars that are a little cooler are white. Even cooler stars shine yellow. Then there are the “orange” and “red” stars.
It seems to us as if the stars twinkle with an unstable light, and the planets shine with an unblinking and...
Why do the stars shine?
As you may remember from your school natural history course, stars are objects that have the ability to emit their own light. In contrast, other celestial bodies, such as planets, satellites, asteroids and comets, are visible in the sky due to reflected light; they do not have their own glow. The only exceptions are meteorites that fall into the Earth's atmosphere and fall due to the force of its gravity. They burn partially or completely during the fall due to friction with air particles, and glow due to this.
But why do stars glow? This is an interesting question, to which astronomers are ready to give a comprehensive answer.
History of the study of stars and their glow
For a long period of time, astronomers could not come to a consensus regarding the nature of starlight. This question has given rise to numerous disputes over many centuries. These disputes were not only of a scientific nature - at the dawn of civilization, people built numerous myths, legends and religious conjectures explaining the presence of stars in the sky and their glow. In the same way, legends and everyday explanations were created for other astronomical phenomena observed in the sky - comets, eclipses, the movements of luminaries.
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Interesting fact : Some civilizations believed that the stars in the sky were the souls of the dead, others believed that these were the heads of nails with which the sky was nailed down. The Sun, on the other hand, was always considered separately; for thousands of years it was not classified as a star; it was too different in its appearance, observed from the surface of the Earth.
With the development of astronomy, the fallacy of such conclusions was revealed, and the stars began to be studied anew - like the Sun. Subsequently, it was possible to clarify that the Sun is also a star. Modern scientists classify the closest star to us as a red dwarf. However, the nature of the glow of the Sun and other stars gave rise to a lot of controversy until very recently.
Theories explaining the glow of stars
In the 19th century, many scientific minds believed that a combustion process occurs on stars - exactly the same as in any earthly stove. But this theory was completely unjustified. It is difficult to imagine how much fuel a star must have in order for it to provide heat for millions of years. Therefore, this version does not deserve consideration. Chemists believed that exothermic reactions occur on stars, which provide a powerful release of large volumes of heat.
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But physicists will not agree with this explanation, for the same reason as with the combustion process. The supply of reactants must be enormous to maintain the stars' luminosity and their ability to produce heat.
After Mendeleev's discoveries, the situation changed again, as the era of studying radiation and radioactive elements began. At that time, the heat and light generated by the stars and the Sun were unconditionally attributed to radioactive decay reactions; this version became generally accepted for decades. Subsequently, it was modified many times.