Why are there stars in the sky at night? Why do the stars shine at night and you can't see them during the day?

In 2013, an amazing event took place in astronomy. Scientists saw the light of a star that exploded ... 12,000,000,000 years ago, in Dark Ages The Universe is the name given in astronomy to the time period of one billion years that has elapsed since the Big Bang.

When the star died, our Earth did not yet exist. And only now the earthlings saw its light - for billions of years wandering through the Universe, farewell.

Why do the stars glow?

Stars shine because of their nature. Each star is a massive ball of gas held together by gravity and internal pressure. Intense fusion reactions are going on inside the ball, the temperature is millions of kelvins.

Such a structure provides a monstrous radiance cosmic body, capable of overcoming not only trillions of kilometers (to the nearest star from the Sun, Proxima Centauri - 39 trillion kilometers), but also billions of years.

Most bright stars observed from Earth - Sirius, Canopus, Toliman, Arcturus, Vega, Capella, Rigel, Altair, Aldebaran, others.


The brightness of the stars directly affects their visible color: blue stars are the most radiant, followed by blue-white, white, yellow, yellow-orange and orange-red.

Why are the stars not visible during the day?

It's all to blame - the closest star to us, the Sun, in the system of which the Earth enters. Although the Sun is not the brightest and not the most big star, the distance between it and our planet is so insignificant in terms of cosmic scale, What sunlight literally floods the Earth, making invisible all other faint glow.

In order to see for yourself what was said above, you can conduct a simple experiment. Make holes in the cardboard box, and mark the light source (desk lamp or flashlight) inside. In a dark room, holes will glow like little stars. And now "turn on the sun" - the overhead room light - the "cardboard stars" will disappear.


This is a simplified mechanism that fully explains the fact that we cannot see starlight during the day.

Are the stars visible during the day from the bottom of mines, deep wells?

During the day, the stars, although not visible, are still in the sky - they, unlike the planets, are static and are always at the same point.

There is a legend that daytime stars can be seen from the bottom deep wells, mines and even high and wide enough (to fit a person) chimneys. It was considered true for a record number of years - from Aristotle, an ancient Greek philosopher who lived in the 4th century BC. e., to John Herschel, an English astronomer and physicist of the XIX century.

It would seem: what is easier - get down into the well and check! But for some reason, the legend lived on, although it turned out to be absolutely false. Stars from the depths of the mine are not visible. Simply because there are no objective conditions for this.

Perhaps the reason for the appearance of such a strange and tenacious statement is the experience proposed by Leonardo da Vinci. To see real image stars observed from the Earth, he made small holes (the size of the pupil or less) in a sheet of paper and applied to the eyes. What did he see? Tiny glowing dots - no jitter or "rays".


It turns out that the radiance of stars is a merit of the structure of our eye, in which the lens bends light, having a fibrous structure. If we look at the stars through a small hole, we pass such a thin beam of light into the lens that it passes through the center, almost without bending. And the stars appear in their true form - as tiny dots.

Each star is a huge luminous ball of gas, like our Sun. A star shines because it releases a huge amount of energy. This energy is formed as a result of the so-called thermonuclear reactions.

Each star is a huge luminous ball of gas, like our Sun. A star shines because it releases a huge amount of energy. This energy is formed as a result of the so-called thermonuclear reactions.Each star contains many chemical elements. For example, the presence of at least 60 elements has been detected on the Sun. Among them are hydrogen, helium, iron, calcium, magnesium and others.
Why do we see the Sun so small? Yes, because it is very far from us. Why do stars look so tiny? Remember how small our huge Sun seems to us - just the size of a soccer ball. This is because it is very far from us. And the stars are much, much further away!
Stars like our Sun illuminate the Universe around them, warm, the planets surrounding them, give life. Why do they only glow at night? No, no, during the day they also shine, you just can't see them. In the daytime, our sun illuminates the blue atmosphere of the planet with its rays, which is why space is hidden behind a curtain. At night, this veil opens, and we see all the splendor of the cosmos - stars, galaxies, nebulae, comets and many other wonders of our Universe.

The question of why the stars shine belongs to the category of children, but, nevertheless, it confuses a good half of adults who have not forgotten something school course physics and astronomy, not that much in childhood skipped.

Explanation of the glow of stars

Stars are inherently gas balls, therefore, in the course of their existence and chemical processes occurring in them emit light. Unlike the moon, which simply reflects the light of the sun, stars, like our sun, glow on their own. If we talk about our sun, it is a medium in size, as well as in age, a star. As a rule, those stars that visually appear larger in the sky are closer, those that are barely visible are further away. There are millions more that are not visible to the naked eye at all. People got acquainted with them when the first telescope was invented.

The star, although it is not alive, has its own life cycle, therefore, at its different stages, it has a different ...

Stars are huge balls of gas that radiate 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 contracts, the gas gradually condenses 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 takes place, the temperature reaches over 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 can stand out closer than a less distant one, but ...

STARS are huge balls of gas that radiate own light, in contrast to the planets and their satellites, which glow by the reflected light of stars.

For example, moonlight is nothing but sunlight reflected by the moon.
Another difference is that it seems to us that the STARS twinkle, while the light of the planets is even and unblinking. The twinkling of stars is caused by the presence various substances V earth's atmosphere.
Since the time of the ancient Greek astronomers, STARS have been divided into groups according to their magnitude. The concept of "magnitude" here does not mean the true size of the stars, but 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 star, astronomers learn a lot about its features, temperature, and even chemical composition.

Thus, STARS, similar to our SUN, illuminate the Universe around them, warm the planets surrounding them, give life. Why do they only glow at night?

A cloudless night outside. As soon as we raise our heads to the sky, we can see huge amount tiny luminous dust particles, located somewhere very far away. These are stars, which are 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 at all, and therefore invented various fables. For example, there was an opinion that these are nails containing the souls of dead people, with which the sky is nailed. But the assumption that the sun is also a star did not exist for a long time. 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 great distance from the Earth, which is sometimes impossible to pass even for a whole human life. 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 adorned the sky. Depending on the position of the observer and the weather, the 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 is nailed, living beings, the souls of people. The list of all possible variations can be very long. Few people thought that our Sun is a star. A huge ball, bursting with heat, was not associated with our ancestors in any way with small silver stars.

In fact, the Sun is the most common 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 at unimaginable distances from the Earth....

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ZIGUNENKO Stanislav Nikolaevich

Paradoxes of our days

Why do the stars glow

N. A. Kozyrev was an astronomer. And it is natural that he began to pick up the keys to world laws not on Earth, but in the Universe. In 1953, he came to the paradoxical conclusion that there is no source of energy in stars at all. Stars live, radiating 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 by itself pass from a colder body to a warmer one."

The statement seems to be self-evident: everyone has seen how, say, the switched off iron gradually becomes more and more ...

Who doesn't like to admire at night the most beautiful view starry sky, look at thousands of bright and not very stars. About why the stars shine, our article will tell.

Stars are cosmic objects that emit a huge amount of heat energy. Such a large release of heat energy, of course, is accompanied by strong light radiation. The light that has reached us, we can observe.

When you look at the starry sky, you will notice that most of the stars are different. Some stars shine with the past, others with blue light. There are also stars that shine orange. Stars are large balls of very hot gases. Since they are heated differently, they have different colour glow. So, the hottest ones shine with blue light. Stars that are slightly colder are white. Even colder stars shine yellow. Then come the "orange" and "red" stars.

It seems to us that the stars twinkle with an unstable light, and the planets shine unblinking and ...

In ancient times, people thought that the stars were the souls of people, the living ones or the nails that held up the sky. They came up with many explanations for why the stars glow at night, and the Sun was long considered a completely different object from the stars.

The problem of thermal reactions occurring in stars in general and on the Sun, the closest star to us, in particular, has long been of concern to scientists in many areas of science. Physicists, chemists, astronomers tried to figure out what leads to the release of thermal energy, accompanied by powerful radiation.

Scientists-chemists believed that exothermic chemical reactions occur in stars, as a result, a large amount of heat is released. Physicists did not agree that in these space objects there are reactions between substances, since no reactions could produce so much light for billions of years.

When Mendeleev's famous table began new era in learning chemical reactions- radioactive elements were found and soon it was the reactions radioactive decay main reason star radiation.

The controversy stopped for a while, as almost all scientists recognized this theory as the most suitable.

Modern theory about the radiation of stars

In 1903, the already established idea of ​​why stars shine and radiate heat was turned over by the Swedish scientist Svante Arrhenius, who electrolytic dissociation. According to his theory, the source of energy in stars is hydrogen atoms, which combine with each other and form more heavy nuclei helium. These processes are caused by strong gas pressure, high density and temperature (about fifteen million degrees Celsius) and occur in the inner regions of the star. This hypothesis began to be studied by other scientists, who came to the conclusion that such a fusion reaction is enough to release the colossal amount of energy that stars produce. It is also likely that the fusion of hydrogen would allow stars to shine for several billion years.

In some stars, helium fusion has ended, but they continue to shine as long as there is enough energy.

The energy released in the interior of stars is transferred to outer areas gas, to the surface of the star, from where it begins to radiate in the form of light. Scientists believe that rays of light travel from the cores of stars to the surface for long tens or even hundreds of thousands of years. After that, the radiation reaches the Earth, which also requires a large number time. So, the radiation of the Sun reaches our planet in eight minutes, the light of the second nearest star, Proxima Centrauri, reaches us in more than four years, and the light of many stars that can be seen with the naked eye has traveled several thousand or even millions of years.