The universe consists of a huge number of cosmic bodies. Every night we can contemplate the stars in the sky, which seem very small, although they are not. In fact, some of them are many times larger than the Sun. It is assumed that a planetary system is formed around each lone star. So, for example, the solar system was formed near the Sun, consisting of eight large, as well as small and comets, black holes, cosmic dust, etc.

The Earth is a cosmic body because it is a planet, a spherical object that reflects sunlight. Seven other planets are also visible to us only due to the fact that they reflect the light of the star. In addition to Mercury, Venus, Mars, Uranus, Neptune and Pluto, which was also considered a planet until 2006, a huge number of asteroids, which are also called minor planets, are also concentrated in the solar system. Their number reaches 400 thousand, but many scientists agree that there are more than a billion of them.

Comets are also cosmic bodies moving along elongated trajectories and approaching the Sun at a certain time. They consist of gas, plasma and dust; overgrown with ice, reach a size of tens of kilometers. When approaching a star, comets gradually melt. From high temperature, the ice evaporates, forming a head and tail, reaching amazing sizes.

Asteroids are the cosmic bodies of the solar system, also called minor planets. Their main part is concentrated between Mars and Jupiter. They consist of iron and stone and are divided into two types: light and dark. The first ones are lighter, the second ones are harder. Asteroids are irregular in shape. It is assumed that they were formed from the remnants of cosmic matter after the formation of the main planets, or they are fragments of a planet located between Mars and Jupiter.

Some cosmic bodies reach the Earth, but, passing through the thick layers of the atmosphere, they heat up during friction and break into small pieces. Therefore, relatively small meteorites fell on our planet. This phenomenon is by no means uncommon; fragments of asteroids are kept in many museums around the world, they were found in 3500 places.

There are not only large objects in space, but also tiny ones. So, for example, bodies up to 10 m in size are called meteoroids. Cosmic dust is even smaller, up to 100 microns in size. It appears in the atmospheres of stars as a result of gas emissions or explosions. Not all space bodies have been studied by scientists. These include black holes, which are found in almost every galaxy. They cannot be seen, it is only possible to determine their location. Black holes have a very strong attraction, so they do not even let go of light. They annually absorb huge volumes of hot gas.

Space bodies have different shapes, sizes, location in relation to the Sun. Some of them are combined into separate groups to make it easier to classify them. So, for example, asteroids located between the Kuiper belt and Jupiter are called Centaurs. Vulcanoids are thought to lie between the Sun and Mercury, although no object has yet been discovered.

The outer space that surrounds our planet consists of a huge number of solid bodies of various sizes, from tiny dust particles to huge boulders.

The concept of small celestial bodies, their sizes and classification

The small celestial bodies of the solar system are those cosmic formations that are neither planets, nor dwarf planets, nor their satellites. This category includes meteoroids, most asteroids and comets, and the Coiler belt bodies.

Currently there is no clear definition of the boundaries of the sizes of small bodies. The smallest in diameter are hundreds of microns, the most impressive - hundreds of kilometers.

However, there are characteristic differences due to which small celestial bodies are classified into separate subspecies:

The most famous "small settlers" of the Cosmos

Small celestial bodies most mentioned in science include:

• asteroid belt- about 98% of asteroids known today lie between two orbits - and. Beyond the orbit of Neptune, there is also a disc-shaped region called the Kuiper belt, most of which is made of ice. The asteroid Ida is special - it has bright blue areas covered with miners.
• Comet Halley is one of the brightest, and the Hale-Bopp comet has already been praised as the most observed of the last century from the category of long-period comets, the period of revolution of which exceeds two centuries.
• Tunguska meteorite, the mystery of which can not be fully unraveled until now. Crashed in Eastern Siberia, brought with it an explosive flash of light so powerful that it started a forest fire, which led to the devastation of an entire area.

Danger to Earth and people

The more impressive the size of celestial bodies, the less likely it is to meet them, so for hundreds and thousands of years the Earth can successfully avoid a fatal collision. However, the history of mankind remembered many such cases.

A direct danger is the fall of meteorites to Earth, the collision of our planet with asteroids and comets.

But still, most often, it is only about rapprochement. The threat arises only when crossing the earth's orbit. With the current level of technological progress, almost all large asteroids can be detected in the near space. Comets are more difficult to detect due to their great distance. In addition, their appearance is quite unpredictable. The most dangerous are long-period ones, which have a high collision velocity. Only more detailed astronomical studies will allow develop reliable methods to protect the planet from space danger.

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Astronomy is a science that deals with the study of celestial objects. Considers stars, comets, planets, galaxies, and also does not disregard existing phenomena occurring outside the Earth's atmosphere, for example,

By studying astronomy, you can get an answer to the question “Celestial bodies that glow themselves. What it is?".

Bodies of the solar system

To find out if there are those that glow themselves, you first need to understand what celestial bodies the solar system consists of.

The solar system is a planetary system, in the center of which is a star - the Sun, and around it are 8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. In order for a celestial body to be called a planet, it must meet the following requirements:

• Make rotational movements around the star.
• To have a shape in the form of a sphere, due to sufficient gravity.
• Do not have other large bodies around its orbit.
• Don't be a star.

The planets do not emit light, they can only reflect the rays of the Sun that hit them. Therefore, it cannot be said that the planets are celestial bodies that glow themselves. Stars are such celestial bodies.

The sun is the source of light on earth

The celestial bodies that glow themselves are the stars. The closest star to Earth is the Sun. Thanks to its light and warmth, all living things can exist and develop. The sun is the center around which the planets, their satellites, asteroids, comets, meteorites and cosmic dust revolve.

The sun appears to be a solid spherical object, because when you look at it, its contours look quite distinct. However, it does not have a solid structure and consists of gases, the main among which is hydrogen, and other elements are also present.

To see that the Sun does not have clear contours, you need to look at it during an eclipse. Then you can see that it is surrounded by a driving atmosphere, which is several times larger than its diameter. With normal glare, this halo is not visible because of the bright light. Thus, the Sun has no exact boundaries and is in a gaseous state.

Stars

The number of existing stars is unknown, they are located at a great distance from the Earth and are visible as small dots. Stars are celestial bodies that glow on their own. What does this mean?

Stars are hot balls, consisting of gas, in which their surfaces have different temperatures and densities. The size of the stars also differ from each other, while they are larger and more massive than the planets. There are stars that are larger than the Sun, and vice versa.

A star is made up of gas, mostly hydrogen. On its surface, from high temperature, the hydrogen molecule breaks up into two atoms. An atom is made up of a proton and an electron. However, under the influence of high temperatures, atoms "release" their electrons, resulting in a gas called plasma. An atom without an electron is called a nucleus.

How stars emit light

The star, at the expense of trying to compress itself, as a result of which the temperature in its central part rises greatly. Begin to occur as a result of the formation of helium with a new nucleus, which consists of two protons and two neutrons. As a result of the formation of a new nucleus, a large amount of energy is released. Particles-photons are emitted as an excess of energy - they also carry light. This light exerts a strong pressure that emanates from the center of the star, resulting in an equilibrium between the pressure emanating from the center and the gravitational force.

Thus, the celestial bodies that glow themselves, namely the stars, glow due to the release of energy during nuclear reactions. This energy is used to contain gravitational forces and to emit light. The more massive the star, the more energy is released and the brighter the star shines.

Comets

The comet consists of an ice clot, in which gases and dust are present. Its core does not emit light, however, when approaching the Sun, the core begins to melt and particles of dust, dirt, gases are thrown into outer space. They form a kind of foggy cloud around the comet, which is called a coma.

It cannot be said that a comet is a celestial body that itself glows. The main light it emits is reflected sunlight. Being far from the Sun, the light of the comet is not visible, and only approaching and receiving the sun's rays, it becomes visible. The comet itself emits a small amount of light, due to the atoms and molecules of the coma, which release the quanta of sunlight they receive. The "tail" of a comet is "scattering dust", which is illuminated by the Sun.

meteorites

Under the influence of gravity, solid objects called meteorites can fall to the surface of the planet. They do not burn up in the atmosphere, but when passing through it, they become very hot and begin to emit a bright light. Such a luminous meteorite is called a meteor.

Under the pressure of air, a meteor can break into many small pieces. Although it gets very hot, the inside of it usually remains cold, because in such a short time that it falls, it does not have time to heat up completely.

It can be concluded that the celestial bodies that glow themselves are stars. Only they are capable of emitting light due to their structure and the processes occurring inside. Conventionally, we can say that a meteorite is a celestial body that itself glows, but this becomes possible only when it enters the atmosphere.

planets are large celestial non-light bodies.

All terrestrial planets are relatively small in size, of considerable density and consisting mainly of solids.
giant planets are large in size, low density and consist mainly of gases. The mass of the giant planets is 98% of the total mass of the planets of the solar system.
In relation to the Sun, the planets are arranged in the following order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
These planets are named after Roman gods: Mercury is the god of trade; Venus is the goddess of love and beauty; Mars is the god of war; Jupiter - god of thunder; Saturn is the god of earth and fertility; Uranus - god of the sky; Neptune is the god of the sea and shipping; Pluto is the god of the underworld of the dead.
On Mercury, the temperature during the day rises to 420 ° C, and at night it drops to -180 ° C. Venus is hot day and night (up to 500 ° C), its atmosphere is almost entirely composed of carbon dioxide. The Earth is located at such a distance from the Sun that most of the water is in a liquid state, which made it possible for life to arise on our planet. The Earth's atmosphere contains oxygen.
On Mars, the temperature regime is similar to that on Earth, but the atmosphere is dominated by carbon dioxide. At low temperatures in winter, carbon dioxide turns into dry ice.
Jupiter is 13 times larger and 318 times heavier than Earth. Its atmosphere is thick, opaque and looks like bands of different colors. Under the atmosphere there is an ocean of liquefied gases.
Stars- red-hot celestial bodies that emit light. They are so distant from the Earth that we see them as bright spots. With the naked eye in the starry sky, you can count about 3000 sight, with the help of a telescope - ten times more.
constellations- groups of nearby stars. Ancient astronomers mentally connected the stars with lines and received certain figures. In the sky of the Northern Hemisphere, the ancient Greeks identified 12 zodiac constellations: Capricorn, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio and Sagittarius. Ancient people believed that each earthly month is connected in a certain way with one of the constellations.
Comets- celestial bodies with luminous tails that over time change their position in the sky and the direction of movement.
The body of a comet consists of a solid core, frozen gases with solid dust, ranging in size from one to ten kilometers. When approaching the Sun, the gases of the comet begin to evaporate. This is how comets grow a luminous tail of gas. The most famous is Halley's Comet (it was discovered in the 17th century by the English astronomer Halley), which appears near the Earth with an approximate interval of 76 years. The last time it approached Earth was in 1986.
Meteora- these are the solid remains of cosmic bodies that fall with great speed through the Earth's atmosphere. At the same time, they burn out, leaving a bright light.
Fireballs- bright giant meteors weighing from 100 g to several tons. Their rapid flight is accompanied by a loud noise, a shower of sparks, and the smell of burning.
meteorites- burnt stone or iron bodies that fell to the Earth from interplanetary space, without ruminating in the atmosphere.
asteroids- these are "baby" planets from 0.7 to 1 km in diameter.

Determining the sides of the horizon for the help of sight

It is easy to find the North Star behind the constellation Ursa Major. If you stand facing the North Star, then in front will be north, behind - south, on the right - east, on the left - west.

CLASSIFICATION OF CELESTIAL BODIES

The processes of formation and development of most cosmic bodies and their systems proceed extremely slowly and take millions and billions of years. However, there are also rapid changes, up to processes of an explosive nature. When studying the cosmogony of stars and galaxies, one can use the results of observations of many similar objects that arose at different times and are at different stages of development.

The largest celestial bodies are stars and planets, and I would like to pay attention to them.

STARS. TYPES OF STARS. THEIR BIRTH, STRUCTURE AND EVOLUTIONARY CYCLE

A star is a massive ball of gas that emits light, held by its own gravity and internal pressure, in the depths of which thermonuclear fusion reactions take place (or have taken place before). The internal life of a star is regulated by the action of two forces: the force of attraction, which opposes the star, holds it, and the force released during the nuclear reactions taking place in the nucleus. It, on the contrary, tends to “push” the star into far space.

The modern (Harvard) spectral classification of stars, developed at the Harvard Observatory in 1890-1924, is a temperature classification based on the type and relative intensity of the absorption and emission lines of the spectra of stars.

Basic (Harvard) spectral classification of stars
	Temperature, K	true color	Visible color
		white-blue	white-blue and white
		yellow-white
		orange	yellowish orange
			orange red

Within the class, stars are divided into subclasses from 0 (hottest) to 9 (the coldest). The sun has a spectral type G2 and an equivalent temperature of 5780 K.

An important fact has been established: the stars were not formed in the Galaxy at the same time, the process of star formation is going on at the present time. Star formation occurs in groups that consist of tens or even hundreds of stars. They arise from the substance of cold and dense molecular clouds as a result of their instability. These molecular clouds have huge sizes and masses (more than 105) and contain 90% of the entire molecular gas of the Galaxy.

In a gas-dust cloud, several concentrations are formed, which are compressed due to the predominance of the forces of gravitational attraction of their particles over the forces of gas pressure. Such compression is accompanied by an increase in the temperature of the clumps and their density. Gradually, the potential energy of condensation turns into heat, the cloud contracts even more and heats up, turning into a star. The stage of development of a star, characterized by compression and not yet having thermonuclear sources of energy, is called a protostar (Greek. protos- "first").

When the central region of the star reaches a temperature of several million degrees Kelvin, thermonuclear fusion reactions begin - the conversion of hydrogen into helium.

The process of star formation can be described in a single way, but the subsequent stages of the evolution of a star depend almost entirely on its mass, and only at the very end of the star's evolution can its chemical composition play a role.

The evolution of a star is very well traced by the Hertzsprung-Russell diagram:

The main sequence is the region on the Hertzsprung-Russell diagram containing stars whose energy source is the thermonuclear reaction of helium fusion from hydrogen. The section of the main sequence of star clusters is an indicator of their age, since the rate of evolution of stars is proportional to their mass.

Stars come in a wide variety of colors and sizes. They range in spectral type from hot blues to cool reds, and in mass from 0.0767 to about 300 solar masses, according to recent estimates. The luminosity and color of a star depend on the temperature of its surface, which, in turn, is determined by its mass. All new stars "take their place" on the main sequence of the diagram. The movement of a star along the diagram means a change in the parameters of the star over time.

Small and cold red dwarfs slowly burn their hydrogen reserves and remain on the main sequence for tens of billions of years, while massive supergiants leave the main sequence after a few million years after formation.

Medium-sized stars like the Sun stay on the main sequence for an average of 10 billion years. It is believed that the Sun is still on it, as it is in the middle of its life cycle. As soon as the star depletes the supply of hydrogen in the core, it leaves the main sequence.