Municipal educational institution "Gymnasium No. 7"

Abstract on the topic:

"How old are the Sun and stars"

Completed by 10th grade student Ekaterina Zaborova

Head: physics teacher N.P. Dobrodumova

2010

Torzhok

“The stars are shining; this simple observational fact immediately leads to the conclusion that they must evolve."

R. L. Seare, R. R. Brownlee

Target: analyze the information of modern ideas about the origin and evolution of the Sun and stars.

Tasks: find out the main sources of solar energy.

Introduction.

If you ask anyonepersonwhich celestial body has highest value for us on Earth, then we will probably hear that Sun . What is the Sun? The first thing that comes to mind is that the sun is a source of light, warmth and comfort, without which the existence of life on Earth would not be possible. Our ancestors understood how much their existence depended on the Sun and therefore treated it with respect, worshiping it and deifying it. Modern research the stars closest to us confirm its endless influence on our lives.

Main unsolved mystery, artifact solar system- this is, perhaps, the age of its inhabitants. No one can say with certainty, for example, how old the Sun, Earth, Moon, etc. are, let alone how old the Solar System itself is. Therefore, the goal that I have set for myself is to analyze the information of modern ideas about the origin and evolution of the Sun and stars.

1.How great is the energy of the Sun and stars

Is it possible to determine the age of the Sun and other stars? Are we able to know whether the Sun is older than the Earth, younger than it, or its peer? Have the Sun and stars always been the same as they are now, and will they always be the same? Were they hotter, will they get colder? Do the Sun and stars change over time? Do they evolve or always remain the same? How long do the Sun and other stars emit? How long will they continue to emit? An energetic approach was used to answer all these questions. Obviously, if you calculate the amount of energy in the Sun and measure the rate at which it consumes energy, you can determine the duration of its existence. If we determine how much of its energy reserve the Sun has already used up, then we can tell how long it has already existed and how much time it has left to exist. The formulated problem can be likened to this task: at the initial moment there is in the stove A kg of coal that burns at a rate And kg/h. If there is currently coal left in the stove IN kg, then how long has the stove been burning and how long will it continue to burn? It is easy to see that the oven task is not difficult. Alas, with regard to the Sun and stars, the solution is far from so simple. First, it is necessary to determine the initial and current energy reserves of the Sun and stars. Secondly, find the corresponding energy consumption rates. In addition, you need to consider that stars have several different sources of energy. Depending on the initial mass and initial composition stars, various processes take place in them and with at different speeds. Finally, the mass, composition and state of stars change all the time as they age. At the same time, the processes occurring in them and the rate at which they consume energy change. Thus, in order to answer the questions posed at the beginning, it is necessary not only to measure a number of parameters celestial bodies, but also to understand how the evolution of stars occurs.

2. What means do we have to study the Sun and stars?

The sun sends us heat and light or, scientifically speaking, radiation various types, including gamma rays, x-rays, visible light, radio waves, as well as neutrons and neutrinos. All conclusions about the structure of the Sun, its age, past, present and future must be made by studying this radiation.It is even more difficult to determine the age of other stars. The naked human eye sees only a few thousand of the brightest of them in the sky. A powerful modern telescope, coupled with a sensitive photographic plate, increases the number of stars accessible to observation to millions. A negligible amount electromagnetic radiation- that's all that comes to us from the stars.Is this enough to judge their properties, structure and age? Once the appropriate research methods were invented, it became possible to say: yes, that’s enough. The closest star to us is our Sun.

The energy of the Sun manifests itself in everything that surrounds us. The life and development of plants are closely related to the activity of the Sun. “A person has the right to call himself the son of the Sun,” wrote K. A. Timiryazev. Any movement on Earth occurs mainly due to the energy that comes to us in the sun's rays. The sun is the source of life on Earth. The great Russian scientist K. A. Timiryazev wrote in his wonderful book “The Life of a Plant”:“Once upon a time, somewhere on Earth, a ray of the Sun fell, but it did not fall on barren soil, it fell on a green blade of wheat sprout, or, better to say, on a chlorophyll grain. Hitting it, it went out, ceased to be light, but did not disappear... In one form or another, it became part of the bread that served us as food. It was transformed into our muscles, into our nerves... Food serves as a source of strength in our body only because it is nothing else. like canned food sun rays...»

In some places globe gigantic trees have survived to this day... The width of one of them is such that 30 people would have to join hands to be able to grasp it at the base. As you know, the age of a tree can be determined by counting the number of rings on its cut. The age of one of these giants, recently felled by a storm, according to the calculation of the number of rings on its cut, turned out to be several thousand years. Every eleventh ring of this tree has a slightly different width, which corresponds to the eleven-year periodicity of sunspots. In addition, and this is especially interesting, in this section you can see that over thousands of years the rings turned out to be approximately the same. This means that during this time the Sun has not changed and sends the same amount of heat and light to the Earth. A study of the development of life on Earth shows that humans have been living on it for several million years, and organic life has been around for more than one billion years. Meanwhile, organic life, associated with the existence of complex polyatomic molecular compounds, is possible only under certain temperature conditions. This means that for at least a billion years the Sun has been emitting approximately the same amount of heat and light as it does now. As for the periods of glaciation that took place on Earth, then, according to a number of scientists, they are not explained by changes in intensity solar radiation, but by a change in the tilt of the earth's axis or by the passage of the solar system through a cold nebula. The earth intercepts only about a billionth of the colossal amount of heat and light emitted by the solar surface in all directions, and this part determines the possibility of life on earth. If we estimate the solar energy reaching the Earth at just one kopeck per kilowatt-hour, it turns out that the Earth receives half a billion rubles worth of it every second. There are stars that emit thousands of times more energy than our Sun. So little energy reaches us from them only because they are located very far from us.

3. Where does the energy of the Sun and stars come from?

Where does this colossal energy of the Sun come from, capable of spending it so wastefully over a huge period of time? Maybe the sun is burning? If the Sun consisted of the best Donetsk coal and received sufficient oxygen for combustion, then with such energy consumption it would burn out in several thousand years. But the Sun has nowhere to get enough oxygen for combustion, and besides, the Sun is too hot for it to burn. Combustion is a chemical reaction of a compound with oxygen, and with such high temperatures, which take place on the Sun, there cannot be chemical compounds. Such a huge expenditure of energy by the Sun has long attracted the attention of scientists.

1. The first to propose methods for determining the age of the Sun were based on calculating itsenergy resources. According to Kelvin's assumptions, the original reserve of thermal energy of the Sun was 10-100 million times greater than the amount of heat it currently consumes annually. Hence, the greatest age of the Sun is equal to 100-500 million years. It should be noted that this entire calculation is rather approximate, and the resulting value, compared with modern data, gives a significantly underestimated value for the age of the Sun.
2. By meteorite hypothesisThe energy of the Sun is maintained by the fall of meteorites onto its surface, the energy of which, upon impact, turns into heat. According to calculations, the number of meteorites sufficient for this turns out to be so large that, as a result of their fall, the mass of the Sun would have to increase noticeably. Meanwhile, in reality this is not observed. In addition, if the energy of the Sun was drawn from meteorite impacts, then the surface of the Sun would be hotter than its internal parts. This would lead to rapid evaporation of the Sun's matter into space, the destruction of the Sun, which is also not true. Thus, the meteorite hypothesis of maintaining the energy of the Sun turns out to be untenable.
3. Due to the action of gravity, a gradual compression of the Sun occurs, and during compression, bodies, as is known, heat up. In 1854, G. Helmholtz expressed the so-called contractionary a hypothesis according to which the energy of the Sun is due to its compression. However, calculations have shown that if the Sun was once infinitely large and then shrank to its current size, then in this case the energy from its compression could be enough to maintain its energy consumption for only 50 million years. This age for the Sun is negligible. Thus, it is obvious that compression alone is not enough to maintain the energy of the Sun.
4. During natural radioactive decay various substances, for example uranium or radium, very significant energy is released. During its transformation into lead, one gram of radium emits energy capable of lifting 1 ton to a height of 685 km. Some scientists proposed using natural energy to explain the source of the Sun's energy. radioactive decay uranium.

However, according to calculations, it turned out that if the source of the Sun’s energy was radioactive decay, then in order to maintain its current energy consumption, the Sun would have to consist entirely of uranium. Meanwhile, it has been proven that the Sun consists of hydrogen by one third by mass, contains even more helium, and there are relatively few heavy elements on the Sun. Other stars also contain relatively small quantity heavy elements.

The natural radioactive decay of uranium occurs slowly and regardless of external conditions, while the intensity of radiation from stars very strongly depends on the temperature in their interiors. There are very hot stars that radiate tens of thousands of times more than our Sun.

Consequently, neither the energy balance of stars nor the temperature dependence of their emission is consistent with the assumption of energy maintenance by natural radioactive decay. Therefore, the assumption that the source of energy of the Sun and stars is the natural radioactive decay of uranium or other radioactive substances, also turns out to be untenable.

So, we see that neither the compression of the Sun, nor the fall of meteorites on it, nor any of chemical reactions(for example, the combustion of coal), nor the natural radioactive decay of uranium or other radioactive substances can explain the origin of the Sun's energy resources. The proof of this is a certain success, albeit a negative one. After all, if we are looking for something, knowing where not to look makes the search easier.

4. What is the key to the origin of the energy resources of the Sun and stars?

Over the past decades, scientists have discovered and studied, first theoretically and then practically, completely new class energy sources - nuclear reactions. It turned out that two types of these reactions have enormous calorific value and are “chain”, those. capable of supporting themselves. One of them is based on the fission of heavy elements, such as uranium. Another reaction, the so-called thermonuclear reaction, is based on the synthesis of light elements, such as helium from hydrogen. Based on their calorific value, these reactions could serve to maintain the energy resources of stars. Let's see if they can actually take place.

The sun and stars mainly consist of light elements - hydrogen, helium and some others, and there are very few heavy elements in them. Thus, with regard to the presence of “fuel”, stellar conditions correspond to the occurrence of thermonuclear fusion reactions. The process of star development currently appears as follows: at first, a huge dark gas cluster slowly contracts under the influence of gravitational forces. As the cluster contracts, the temperature and pressure in its depths increase increasingly. Thus, conditions are created for intense nuclear reactions. When nuclear fusion reactions flare up, a huge amount of energy is released and the temperature of the cluster increases sharply. In this case, the cluster becomes self-luminous, i.e., it is born like a star. In this process, the initial compression of the celestial body plays the role of “launching” the nuclear energy source of the star.

IN various stars Various nuclear reactions take place, and in the same star, during its development, some nuclear reactions replace others. First, the deuterium “combustion” reaction occurs. At the same time, the temperature of the star increases, the pressure inside it increases, and the compression of the star slows down or stops until the deuterium burns out. it contains nuclear reactions that synthesize helium from hydrogen.

These are the ones nuclear reactions have the main energy value for our Sun and many other stars. When they occur, four nuclei of hydrogen atoms form the nucleus of a helium atom through a series of successive transformations. Thus, in huge and powerful “furnaces” operating in the depths of the Sun and stars, hydrogen serves as “fuel”, and as a result of its “combustion” helium is obtained.

After a significant part of the hydrogen is consumed and, thus, this source of energy is exhausted, the star contracts again, and the temperature of the substance in its depths and its density increase even more. This is another cardinal stage in the life of a star. Now the helium synthesis reaction begins to take place in it, leading to the formation of even heavier elements. The average molecular weight of the star's matter increases. It becomes less transparent. The temperature of its interior rises even more, and its shell swells. In this case, the star turns into a red giant. The evolution of stars does not end there. Since at all previous stages of their lives they generously scattered particles and radiation, over time their mass decreases and their composition changes. Most of them turn into small, very dense and weakly luminous cosmic bodies - the so-called “dwarfs”. In our Sun, as we have already said, the reaction of the synthesis of helium from hydrogen takes place, and it is somewhere around the middle of this stage of its existence. Thus, in order to determine its age, it is necessary to measure the relative content of hydrogen and helium in it.

How to do this?

5. Determination of the composition and age of the Sun and stars

At first glance, it may seem that in order to determine the composition of the Sun or a star, it is necessary to extract at least a little of its matter. However, this is not true. The composition of a celestial body can be determined by observing the light coming to us from it using special instruments. This method is calledspectral analysisand has great value in astronomy. The essence of this method can be understood as follows. Let us place an opaque barrier with a narrow slit in front of the electric lamp, a glass prism behind the slit, and a white screen somewhat further away. A heated solid metal filament glows in an electric lamp. A narrow beam of white light cut by a slit, passing through a prism, is decomposed into its component colors and gives a beautiful color image on the screen, consisting of sections of different colors that continuously transform into each other - this is the so-called continuous light spectrum, similar to a rainbow. The type of spectrum of a heated solid does not depend on its composition, but only on the temperature of the body. A different situation occurs when substances glow in a gaseous state. When gases glow, each of them glows with a special, unique light. When this light is decomposed using a prism, a set of colored lines, or line spectrum, is obtained, characteristic of each given gas. This is, for example, the glow of neon, argon and other substances in gas-light tubes, or so-called cold light lamps.

Spectral analysis is based on the fact that each given substance can be distinguished from all others by its emission spectrum.When spectral analysis of a mixture of several substances, the relative brightness of individual lines characteristic of each substance can be used to determine the relative content of a particular impurity. Moreover, the measurement accuracy is such that it makes it possible to determine the presence of a small impurity, even if it is only one hundred thousandth of the total number substances. Thus, spectral analysis is not only a qualitative, but also an accurate quantitative method for studying the composition of a mixture. By pointing telescopes at the sky, astronomers study the patterns of movement of stars and the composition of the light they emit. Based on the nature of the movement of celestial bodies, the sizes of stars, their mass, etc. are determined. Based on the composition of the light emitted by celestial bodies, it is determined using spectral analysis chemical composition stars The relative abundance of hydrogen and helium in the star under study is determined by comparing the brightness of the spectra of these substances.

Since the development of a star is accompanied by the continuous transformation of hydrogen into helium inside it, then what older star, the less hydrogen and more helium in its composition. Knowing their relative abundance allows us to calculate the age of the star. However, this calculation is not at all simple, because during the evolution of stars, their composition changes and their mass decreases. Meanwhile, the rate at which the conversion of hydrogen into helium occurs in a star depends on its mass and composition. Moreover, depending on the initial mass and initial composition, these changes occur at different rates and in slightly different ways. Thus, in order to correctly determine the age of a star from the observed quantities - luminosity, mass and composition, it is necessary to restore to some extent the history of the star. This is what makes all the calculations quite complicated, and their results not very accurate. Nevertheless, corresponding measurements and calculations have been made for many stars. According to A.B. Severny, the Sun contains 38% hydrogen, 59% helium, and 3% other elements, including about 1% carbon and nitrogen. In 1960, D. Lambert, based on data on the mass, luminosity and composition of the Sun, as well as detailed calculations of its supposed evolution, obtained the age of the Sun equal to 12 -10 9 years. When studying the history of the development of celestial bodies, there is neither the need nor the opportunity to follow any one star from its birth to its old age. Instead, many stars can be studied at different stages of their development. As a result of such research, it was possible to clarify not only the present, but also the past and future of stars, and in particular our Sun.

At first, the Sun spent its mass and energy very wastefully and relatively quickly moved on to its current state, characterized by a calmer and more even existence, in which only extremely slow changes in its luminosity, temperature and mass occur. At this already “mature” age, the Sun will exist for many more billions of years.

Then, due to accumulation large quantity helium, the transparency of the Sun will decrease and, accordingly, its heat transfer will decrease. This will lead to even greater heating of the Sun. By this time, the reserves of hydrogen “fuel” in the Sun will almost dry up, therefore, after a relatively short flare-up of the Sun, its relatively rapid fading will begin. However, all this will not happen to our Sun soon, no less than in ten billion years.

Conclusion.

Be that as it may, astronomers unanimously agree that the entire solar With The system - both the Sun and the planets - were formed as a result of a common process. In other words, if the Earth in its current form has existed for 4.7 billion years, then the entire solar system (including the Sun) in its current form can be considered to have existed for 4.7 billion years.

References

1. Levitan E. P. Astrophysics for schoolchildren. A manual for students. M.: “Enlightenment”, 1997.

“The stars are shining; this simplest observational fact immediately leads to the conclusion that they must evolve." R. L. Seare, R. R. Brownlee

Purpose: to analyze the information of modern ideas about the origin and evolution of the Sun and stars. Objectives: find out the main sources of solar energy

What is the Sun? The first thing that comes to mind is that the sun is a source of light, warmth and comfort, without which the existence of life on Earth would not be possible.

The main unsolved mystery, an artifact of the solar system, is, perhaps, the age of its inhabitants. No one can say with certainty, for example, how old the Sun, Earth, Moon, etc. are, let alone how old the Solar System itself is.

1. How great is the energy of the Sun and stars? To answer all these questions, an energy approach was used.

“Once upon a time, somewhere on Earth, a ray of the Sun fell, but it did not fall on barren soil, it fell on a green blade of wheat sprout, or, better to say, on a chlorophyll grain. Hitting it, it went out, ceased to be light, but did not disappear... In one form or another, it became part of the bread that served us as food. It was transformed into our muscles, into our nerves... Food serves as a source of strength in our body only because it is nothing else. like a can of sun rays..." K. A. Timiryazev

1. What means do we have to study the Sun and stars? 2. Where does the energy of the Sun and stars come from?

Methods for determining the age of the Sun were the first to be proposed, based on calculating its energy resources. Meteorite hypothesis. Contraction hypothesis. Radioactive decay.

Nuclear reactions are of primary energy importance for our Sun and many other stars. In huge and powerful “furnaces” operating in the depths of the Sun and stars, hydrogen serves as “fuel”, and as a result of its “combustion” helium is obtained.

In our Sun, as we have already said, the reaction of synthesis of helium from hydrogen takes place, and it is somewhere around the middle of this stage of its existence. Thus, in order to determine its age, it is necessary to measure the relative content of hydrogen and helium in it.

5. Determination of the composition and age of the Sun and stars Spectral analysis is based on the fact that each given substance can be distinguished from all others by the spectrum of its radiation

Astronomers unanimously agree that the entire solar system - both the Sun and the planets - was formed as a result of a common process. In other words, if the Earth in its current form has existed for 4.7 billion years, then the entire solar system (including the Sun) in its current form can be considered to have existed for 4.7 billion years.

The Sun is the “heart” of the Solar System, and planets and satellites revolve around it. Scientists argue that it is enough to change the mass of the sun or its size even slightly, and life on our planet simply would not exist. We have prepared for our readers a selection of very interesting facts about the only star in the solar system.

1. The sun is really big

In fact, the Sun makes up more than 99.8% of total mass Solar system. This is not a mistake - all planets, their moons and all other small space objects make up less than 0.2% of the mass of the Solar System. To be more precise, the mass of the Sun is about two nonillion kilograms (that's two point thirty zeros). The volume of the Sun is approximately 1.3 million planets. equal to Earth.

In fact, the mass of the Sun is quite often used in astronomy as a standard unit of measurement for large objects. When we're talking about about stars, nebulae, or even galaxies, astronomers often use the comparison to the Sun to describe their mass.

2. On a galactic scale, the Sun is not particularly large

Although we were just talking about the fact that the Sun is indeed very large, but this is only in comparison with other objects in the solar system. There are much more massive things in the Universe. The Sun is classified as a G-type star, which is generally called a yellow dwarf.

As the name suggests, there are much larger stars, classified as giants, supergiants and hypergiants. The red supergiant Uy Scuti is located 9,500 light-years from Earth. This is currently the largest famous star with a diameter approximately 1700 times greater than that of the Sun. Its circumference is 7.5 billion kilometers. Even light takes almost seven hours to circle a star. If Uy Scuti were in the Solar System, then the surface of the star would extend beyond the orbit of Jupiter.

3. What happens when the Sun dies

Stars can live for a very long time, billions of years, but eventually they too die. Further fate stars depends on their size. The remains of smaller stars turn into so-called brown dwarfs. Massive stars die more violently - they go supernova or even hypernova and collapse into neutron star or a black hole. In rare cases, these giants can even explode, followed by a gamma-ray burst.

The sun is somewhere in the middle - it will not explode, but it will not “deflate” either. Once the Sun runs out of hydrogen fuel, it will begin to collapse in on itself under the influence of own weight, causing the core to become denser and hotter. This will cause the Sun to expand and become a red giant. Eventually, it will collapse into a white dwarf - a tiny stellar remnant of incredible density (the size of the Earth, but the mass of the Sun).

4. What does the Sun consist of?

It is composed primarily of hydrogen and helium, like most stars. To be more precise, it is about 71% hydrogen, 27% helium, and the remaining 2% comes from trace amounts of tens chemical elements mainly oxygen and carbon.

5. How hot is the Sun?

The temperature of the Sun really depends on what part of the Sun we are talking about. The core of the Sun is insanely hot - temperatures there reach 15 million degrees Celsius. In the chromosphere, the temperature is “only” several thousand degrees. However, temperatures quickly rise to millions of degrees in the Sun's outer layer, the corona. Why this is so, scientists do not know for sure.

6. How old is the Sun

The age of the Sun is about 4.6 billion years. Its age was calculated based on the ages of other things in the solar system that can be dated more accurately, such as meteorites or even rocks Earth. Naturally, this is true under the assumption that the solar system formed as a single whole. The lifespan of a G-type star is from 9 to 10 billion years.

7. How bright is the Sun?

Sirius A is gigantic, while the bright star Sirius B (right) is much smaller. Obviously, the Sun is the brightest in the daytime sky because it is much closer to Earth than any other star. In the night sky, the brightest star is Sirius. The second brightest is Canopus.

Apparent magnitude is the term used to indicate the brightness of a celestial object from Earth. The Sun has an apparent magnitude of -27.

8. How fast the sun rotates

The rotation of the Sun is a little difficult to calculate because it varies depending on the region. In short, without explanation, the Sun takes about 25.4 days to complete a revolution. The Sun does not actually rotate like solid, similar to Earth. It rotates fastest at the equator (24.5 days) and slowest near the poles (38 days).

Regarding the speed of the Sun in the Universe, the entire Solar System orbits around the center Milky Way at a speed of 828,000 km/h. One complete revolution, known as a galactic year, takes approximately 225 - 250 million Earth years.

9. What are sunspots?

Sometimes on the surface of the Sun you can observe dark spots, known as sunspots. They have more low temperature(about 1226 degrees Celsius) than the rest of the solar surface and appear due to fluctuations magnetic field Sun. Some may be large enough to be seen with the naked eye. Sometimes groups of more than 100 appear sunspots simultaneously. However, this happens extremely rarely.

10. The sun changes its magnetic field

Every 11 years South and North magnetic poles change places. This also happens on Earth, but much less frequently. IN last time this happened about 800,000 years ago.

Line UMK B. A. Vorontsov-Velyaminov. Astronomy (11)

Astronomy

Natural science

How old is the Sun? Can the Sun cool down?

"What will happen if the Sun goes out?" – the question can be asked either in a scared voice or in a curious one. "How old is the Sun?" – is also one of the popular questions for children and adults.
In our new column “Why” we will regularly answer the most interesting ones!

Solar Passport

The Sun, the central body of the Solar System, is a typical representative of stars, the most common bodies in the Universe. The mass of the Sun is 2 * 10 to the 30th power kg. Like many other stars, the Sun is a huge ball that consists of hydrogen-helium plasma and is in equilibrium (more on that below).

How old is the Sun?

It is 4.6 billion years old. Quite a lot, right? Considering that life (arthropods - the ancestors of modern insects) appeared on our planet about 570 million years ago. The simplest organisms much earlier -about 3.5 billion years ago

Can the Sun go out?

There is no need to be afraid that the Sun will go out, because first it will flare up very, very strongly!
Inside the star (and any star that is in a state of equilibrium between pressure from inside and pressure from outside), at a certain moment a new stage of thermonuclear fusion flares up. Temperatures become so high - pressure increases so much that the outer shells of the star swell. The star will change irreversibly, turning into a red giant of enormous size. Our Sun will turn into the same giant.
Is the Sun Big?

The diameter of the Sun is almost 1,400,000 km. Many? Compare with the picture below! Millions of planets the size of Earth can fit inside the Sun. 99.8% of the mass of the Solar System is concentrated in the Sun. And from 0.2% of everything else the planets are made (with 70% of the planetary mass coming from Jupiter). By the way, the Sun is constantly losing weight: it loses 4 million tons of its mass every second - they fly away in the form of radiation, every moment about 700 million tons of hydrogen turn into 696 tons of helium.

When and how will our Sun explode?

It would be more correct to say that it will turn into a red giant. IN at the moment The Sun is a yellow dwarf and simply burns hydrogen. Throughout its entire existence - 5.7 billion years, as we have already said - the Sun has been in a stable mode of hydrogen burning. And this fuel will last him for 5 billion years (more than the Earth has existed since the beginning of time!)

After the next stages of synthesis are turned on, the Sun will turn red, increase in size - up to the Earth's orbit (!) - and absorb our planet. And, yes, before that he will gobble up Venus and Mercury. But life on Earth will cease even before the Sun begins its transformation, because increasing luminosity and rising temperatures will lead to the fact that our oceans will evaporate a billion years before that.

How hot is the Sun?

The temperature on the surface of the Sun is approximately 6 thousand degrees Celsius. Inside the Sun, where thermonuclear reactions occur without stopping, the temperature is MUCH higher - it reaches 20 million degrees Celsius.

Is this what happens to all the stars? How then does life appear?

The sun is still a very small star, and therefore can work for a long time, steadily burning its hydrogen. Large stars, due to their enormous mass and the need to constantly resist gravitational compression (what is outside) very quickly spend their fuel with their powerful backpressure. As a result, their cycle is completed not in billions, like the Sun, but in millions of years. Because of this, life on nearby planets does not have time to arise.
Advice to future astronauts: if you are looking for life on planets in other systems, do not choose massive stars, but rather immediately focus on a star of the solar class (Class G - surface temperature 5000–6000 degrees. Color yellow).

The textbook by B. A. Vorontsov-Velyaminov, E. K. Strout meets the requirements of the Federal State Educational Standard and is intended for the study of astronomy on basic level. It retains the classical structure of presentation educational material, much attention is paid to the current state of science. Over the past decades, astronomy has made enormous strides. Today it is one of the fastest growing areas of natural science. New established data on the study of celestial bodies from spacecraft and modern large ground-based and space telescopes have found their place in the textbook.

In the beginning there was darkness... Or rather, there was a cloud of dust and gas in outer space, far from the center of our Galaxy, on the outskirts of one of its spiral arms. This nebula had a torque, that is, it rotated, and did not hang motionless. In addition, it had a very large mass. As a result, its substance began to accumulate in the center, becoming increasingly denser and warmer. And this happened about 4.6 billion years ago.

The process of evolution of the gas and dust cloud, of course, did not end there. Its more massive central part began to influence other regions of the nebula with its gravity. As a result of rotation, this cloud acquired a flatter shape - a protoplanetary disk with a diameter of 200 astronomical units was formed. Let me remind you that one astronomical unit is the distance from the Earth to the Sun, that is, 150 million kilometers.

In the center of the protoplanetary disk, the density of matter became so high that a protostar was formed - a very dense and hot, but small object. This protostar continued to collect all the matter surrounding it, constantly increasing its mass and density. This continued for approximately 50 million years. Finally, the density of hydrogen at its center allowed the thermonuclear reaction to start. This is how the Sun lit up.

Planets and other objects of the solar system gradually formed from the remains of the gas and dust cloud. Of course, everything then looked completely different than it does now. For example, just inside the Earth’s orbit there were about 50-100 objects comparable in size to the planet earth type. They had very different orbits and gradually, colliding with each other, generated a sea of ​​​​debris. According to some hypotheses, the Moon was born there as a result of the collision of two such protoplanets.

The orbits of the planets were far from circular, as they are now. They were elongated - elliptical. In the process of evolution, under the influence of the gravity of neighbors and braking in the gas cloud, the orbits of the planets were somewhat smoothed out.

According to research, the entire solar system was formed at approximately the same time. Thus, the oldest samples found on Earth are zircon crystals. Their age is determined to be 4.4 billion years. At the same time, analysis of meteorites showed that their elements are 4.5 billion years old, that is, approximately the same. This suggests that the formation of all objects in the Solar System occurred at the same time. And life on Earth began only 570 million years ago...

It is interesting to study the past, but it is no less interesting to learn the future of our Sun and planet. About the Sun, everything is more or less clear - the evolution of stars has been studied quite well, but the fate of the planets is not so clear. But, in order...

The Sun is a star that belongs to the type of yellow dwarf. Over time, it will become hotter and in 1 billion years it will become impossible to live on Earth. Next, the process of hydrogen combustion will begin in the outer layers of the Sun, since it will end below. The Sun will greatly increase in size and become a red giant. Red color - because the surface of the star will be much colder than the current one - only 2600 degrees. The red giant will be at the center of the solar system in about 5 billion years. Venus will be inside the expanding Sun. But by that time, earthlings will have to move to another star system - after the same 5 billion years, a collision of our Galaxy and the Andromeda Nebula, an even larger galaxy, should occur...

The red giant will then shed half its mass, causing chaos among the planets and forming a planetary gas nebula. And the Sun itself will become a white dwarf - a super-dense, very bright star that will become dimmer and dimmer until it goes out completely and becomes a black dwarf...

What about the planets? Their fate over such a period of time is difficult to predict. The solar system is stable in the sense that the planets will not go anywhere, but here is their fate... The orbits of the planets are now impossible to calculate for a period greater than several million or billions of years. For example, there is a possibility that Mercury's orbit will become more elongated and eventually Venus will throw it out of the solar system. It could also collide with Venus or change its orbit under its influence so that it reaches the Earth. The situation is the same with Mars - its elliptical orbit can eventually pass dangerously close to the Earth, and the results can be very different - from mutual changes in orbits to a collision. And this can happen to any planet - their mutual influence is too diverse.

It is assumed that the age of the Sun is at least equal to the age of the Earth. The significantly larger source of solar radiation energy is nuclear energy, not gravitational energy.  

The geological age of the Earth is approaching five billion years; This is or is slightly greater than the age of the Sun, and the oldest stars in the Galaxy are more than 10 billion years old. The history of the Universe as a whole is 15 - 18 billion years, and before the formation modern planets, stars and galaxies, all its matter was, apparently, an almost homogeneous medium. The knowledge accumulated over many decades about the structure and evolution of celestial bodies, the observational discoveries of the last half century, and especially the discovery of the expansion of the Universe and the existence of isotropic cosmic microwave background radiation in it, now allow us to form a certain idea about the properties of the cosmic environment in the prestellar, pre-galactic era, about physical processes, which led to the formation of the observable structures of the Universe from homogeneous matter. This is the content of modern cosmogony.  

Thomson put forward a hypothesis according to which the radiation of the Sun is supported by gravitational energy released during its compression. Estimate the age of the Sun / using this hypothesis, assuming that in the initial state the matter of the Sun was uniformly distributed throughout the entire infinite space, and in the final state the density of the solar matter is the same throughout the entire volume of the Sun.  

We do not know the evolutionary age of the Sun with sufficient certainty, since we do not know the helium content in it. It is believed that the evolutionary age of the Sun lies somewhere in the region considered.  

The value (1.2.33) agrees well with data on the ages of stars and galaxies (12 billion years), obtained on the basis of completely different considerations. It is also consistent with the geological age of the Earth (4 - 5 billion years), which serves as a lower limit for the age of the Sun.  

The fuel that generates solar heat is thus hydrogen, and the product of its combustion is helium. It can be easily calculated that, with a constant release of energy, the hydrogen in the Sun will last for approximately 1011 years. The age of the Sun should be taken to be approximately 5 billion years. Consequently, only about one-twentieth of the original fuel supply has been consumed in it.  

Solid lines show data for dust particles consisting of refractory substances, dashed lines - for dust particles consisting of volatile substances. For comparison, the arrows indicate the age of the Sun (right arrow) and the rotation period of the Galaxy at a distance corresponding to the distance of the Sun from the galactic center.  

The energy released in this case turned out to be too great, and therefore after some time an explosion occurred in the form of a Supernova, during which the nuclei of the heaviest elements were formed; the mass of the star decreased due to the ejection of matter. This entire process could be repeated repeatedly until the mass of the central massive star fell below a critical limit. Such a system should have a lifetime of about 5 billion years, which corresponds to the age of the Sun and provides a time interval sufficient for chemical, geological and biological evolution to reach modern levels.  

Pages:      1