The sun is a planet in the solar system. Outer region of the solar system

Not so long ago, anyone educated person to the question of how many planets are in the solar system, he would answer without hesitation - nine. And he would be right. If you do not particularly follow the events in the world of astronomy and are not a regular viewer of the Discovery Channel, then today you will answer the same question to the question posed. However, this time you will be wrong.

And here's the thing. In 2006, namely, on August 26, 2.5 thousand participants in the congress of the International Astronomical Union made a sensational decision and actually crossed out Pluto from the list of planets in the solar system, because 76 years after the discovery, it ceased to meet the requirements set by scientists for the planets.

Let's first understand what a planet is, and also how many planets in the solar system astronomers have left us, and consider each of them separately.

A bit of history

Previously, a planet was considered to be any body that revolves around a star, glows with light reflected from it, and has a size larger than that of asteroids.

Even in ancient Greece, seven luminous bodies were mentioned that move across the sky against the background of fixed stars. These cosmic bodies were: Sun, Mercury, Venus, Moon, Mars, Jupiter and Saturn. Earth was not included in this list, since the ancient Greeks considered the Earth to be the center of all things. And only in the 16th century, Nicolaus Copernicus, in his scientific work entitled “On the Revolution of the Celestial Spheres,” came to the conclusion that not the Earth, but the Sun, should be in the center of the planetary system. Therefore, the Sun and the Moon were removed from the list, and the Earth was added to it. And after the advent of telescopes, Uranus and Neptune were added, in 1781 and 1846, respectively.
Pluto was considered the last discovered planet in the solar system from 1930 until recently.

And now, almost 400 years after Galileo Galilei created the world's first telescope for observing stars, astronomers have come to the next definition of a planet.

Planet- this is a celestial body that must satisfy four conditions:
the body must revolve around a star (for example, around the Sun);
the body must have sufficient gravity to be spherical or close to it;
the body should not have other large bodies near its orbit;

The body does not have to be a star.

In its turn star- This is a cosmic body that emits light and is a powerful source of energy. This is explained, firstly, by the thermonuclear reactions occurring in it, and secondly, by the processes of gravitational compression, as a result of which great amount energy.

Planets of the solar system today

solar system- This is a planetary system that consists of a central star - the Sun - and all natural space objects revolving around it.

So, today the solar system consists of of the eight planets: four inner, so-called terrestrial planets, and four outer planets, called gas giants.
The terrestrial planets include Earth, Mercury, Venus and Mars. All of them consist mainly of silicates and metals.

The outer planets are Jupiter, Saturn, Uranus and Neptune. The composition of gas giants consists mainly of hydrogen and helium.

The sizes of the planets in the solar system vary both within groups and between groups. So, the gas giants are much larger and more massive than the terrestrial planets.
Closest to the Sun is Mercury, then as far as the distance: Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

It would be wrong to consider the characteristics of the planets of the solar system without paying attention to its main component: the Sun itself. Therefore, we will start with it.

Sun

The sun is the star that gave rise to all life in the solar system. Planets, dwarf planets and their satellites, asteroids, comets, meteorites and cosmic dust revolve around it.

The sun arose about 5 billion years ago, is a spherical, hot plasma ball and has a mass that is more than 300 thousand times the mass of the Earth. The surface temperature is over 5,000 degrees Kelvin, and the core temperature is over 13 million K.

The Sun is one of the largest and brightest stars in our galaxy, which is called the Milky Way galaxy. The Sun is located at a distance of about 26 thousand light years from the center of the Galaxy and makes a complete revolution around it in about 230-250 million years! For comparison, the Earth makes a complete revolution around the Sun in 1 year.

Mercury

Mercury is the smallest planet in the system and is closest to the Sun. Mercury has no satellites.

The surface of the planet is covered with craters that arose about 3.5 billion years ago as a result of massive bombardments by meteorites. The diameter of the craters can range from a few meters to more than 1000 km.

The atmosphere of Mercury is highly rarefied, consists mainly of helium and is blown by the solar wind. Since the planet is located very close to the Sun and does not have an atmosphere that would keep warm at night, the temperature on the surface ranges from -180 to +440 degrees Celsius.

By earthly standards, Mercury makes a complete revolution around the Sun in 88 days. On the other hand, a Mercury day is equal to 176 Earth days.

Venus

Venus is the second closest planet to the Sun in the solar system. Venus is only slightly smaller than Earth, which is why it is sometimes referred to as "Earth's sister". Has no satellites.

The atmosphere is made up of carbon dioxide with impurities of nitrogen and oxygen. The air pressure on the planet is more than 90 atmospheres, which is 35 times more than the earth.

Carbon dioxide and, as a result, the greenhouse effect, a dense atmosphere, as well as proximity to the Sun, allow Venus to carry the title of "hottest planet". The temperature on its surface can reach 460°C.

Venus is one of the brightest objects in the Earth's sky after the Sun and Moon.

Earth

Earth is the only known planet in the universe today that has life on it. The earth has the large sizes, mass and density among the so-called inner planets of the solar system.

The age of the Earth is about 4.5 billion years, and life appeared on the planet about 3.5 billion years ago. The Moon is a natural satellite, the largest of the satellites of the terrestrial planets.

The atmosphere of the Earth is fundamentally different from the atmospheres of other planets due to the presence of life. Most of the atmosphere is nitrogen, but it also contains oxygen, argon, carbon dioxide and water vapor. Ozone layer and the Earth's magnetic field, in turn, weaken the life-threatening effects of solar and cosmic radiation.

Due to the carbon dioxide contained in the atmosphere, the greenhouse effect also takes place on Earth. It does not appear as strongly as on Venus, but without it, the air temperature would be approximately 40 ° C lower. Without the atmosphere, temperature fluctuations would be very significant: according to scientists, from -100 ° C at night to + 160 ° C during the day.

About 71% of the Earth's surface is occupied by the oceans, the remaining 29% are continents and islands.

Mars

Mars is the seventh largest planet in the solar system. The "Red Planet", as it is also called due to the presence of a large amount of iron oxide in the soil. Mars has two moons: Deimos and Phobos.
The atmosphere of Mars is highly rarefied, and the distance to the Sun is almost one and a half times greater than that of the Earth. Therefore, the average annual temperature on the planet is -60 ° C, and temperature drops in some places reach 40 degrees during the day.

Distinctive features of the surface of Mars are impact craters and volcanoes, valleys and deserts, ice polar caps like those on Earth. The highest mountain in the solar system is located on Mars: the extinct volcano Olympus, whose height is 27 km! As well as the largest canyon: the Valley of the Mariner, the depth of which reaches 11 km, and the length is 4500 km.

Jupiter

Jupiter is the most big planet solar system. It is 318 times heavier than the Earth, and almost 2.5 times more massive than all the planets in our system combined. In its composition, Jupiter resembles the Sun - it consists mainly of helium and hydrogen - and radiates a huge amount of heat, equal to 4 * 1017 watts. However, in order to become a star like the Sun, Jupiter must be another 70-80 times heavier.

Jupiter has as many as 63 satellites, of which it makes sense to list only the largest ones - Callisto, Ganymede, Io and Europa. Ganymede is the largest moon in the solar system, larger than even Mercury.

Due to certain processes in the inner atmosphere of Jupiter, many vortex structures appear in its outer atmosphere, for example, stripes of clouds of brown-red shades, as well as the Great Red Spot, a giant storm known since the 17th century.

Saturn

Saturn is the second largest planet in the solar system. The hallmark of Saturn is, of course, its ring system, which consists mainly of ice particles of various sizes (from tenths of a millimeter to several meters), as well as rocks and dust.

Saturn has 62 moons, the largest of which are Titan and Enceladus.
In its composition, Saturn resembles Jupiter, but in density it is inferior even to ordinary water.
The outer atmosphere of the planet looks calm and homogeneous, which is explained by a very dense layer of fog. However, the wind speed in some places can reach 1800 km/h.

Uranus

Uranus is the first planet to be discovered with a telescope, and also the only planet in the solar system that wraps around the sun, "lying on its side."
Uranus has 27 moons named after Shakespearean heroes. The largest of them are Oberon, Titania and Umbriel.

The composition of the planet differs from the gas giants in the presence of a large number of high-temperature modifications of ice. Therefore, along with Neptune, scientists have identified Uranus in the category of "ice giants". And if Venus has the title of "hottest planet" in the solar system, then Uranus is the coldest planet with a minimum temperature of about -224 ° C.

Neptune

Neptune is the most distant planet from the center of the solar system. The history of its discovery is interesting: before observing the planet through a telescope, scientists calculated its position in the sky using mathematical calculations. This happened after the discovery of inexplicable changes in the movement of Uranus in its own orbit.

To date, 13 satellites of Neptune are known to science. The largest of them - Triton - is the only satellite that moves in the opposite direction to the rotation of the planet. Against the rotation of the planet blow also the most fast winds in the solar system: their speed reaches 2200 km / h.

The composition of Neptune is very similar to Uranus, therefore it is the second "ice giant". However, like Jupiter and Saturn, Neptune has an internal source of heat and radiates 2.5 times more energy than it receives from the Sun.
Blue colour the planet is given traces of methane in the outer layers of the atmosphere.

Conclusion
Pluto, unfortunately, did not have time to get into our parade of planets in the solar system. But it is absolutely not worth worrying about this, because all the planets remain in their places, despite changes in scientific views and concepts.

So, we answered the question of how many planets are there in the solar system. There are only 8 .

The solar system is a system of planets, which includes its center - the Sun, as well as other objects of the Cosmos. They revolve around the sun. More recently, 9 objects of the Cosmos that revolve around the Sun were called “planet”. Now scientists have established that beyond the boundaries of the solar system there are planets that revolve around stars.

In 2006, the Union of Astronomers declared that the planets of the solar system are spherical cosmic objects revolving around the sun. On the scale of the solar system, the Earth appears to be extremely small. In addition to the Earth, eight planets revolve around the Sun in their individual orbits. All of them are larger than the Earth. They rotate in the plane of the ecliptic.

Planets in the solar system: types

Location of the terrestrial group in relation to the Sun

The first planet is Mercury, followed by Venus; next comes our Earth and finally Mars.
The terrestrial planets do not have many satellites or moons. Of these four planets, only Earth and Mars have moons.

The planets that belong to the terrestrial group are highly dense, composed of metal or stone. Basically, they are small and rotate around their own axis. Their rotation speed is also low.

gas giants

These are the four space objects that are at the greatest distance from the Sun: Jupiter is at number 5, followed by Saturn, then Uranus and Neptune.

Jupiter and Saturn are impressive planets, made up of compounds of hydrogen and helium. The density of gas planets is low. They rotate at high speed, have satellites and are surrounded by asteroid rings.
“Ice giants”, which include Uranus and Neptune, are smaller, their atmospheres contain methane, carbon monoxide.

Gas giants have a strong gravitational field, so they can attract many space objects, unlike the terrestrial group.

According to scientists, asteroid rings are the remains of moons altered by the gravitational field of the planets.

dwarf planet

Dwarfs are space objects, the size of which does not reach the planet, but exceeds the dimensions of the asteroid. There are many such objects in the solar system. They are concentrated in the Kuiper belt region. The satellites of the gas giants are dwarf planets that have left their orbit.

Planets of the solar system: the process of emergence

According to the hypothesis of cosmic nebulae, stars are born in clouds of dust and gas, in nebulae.
Due to the force of attraction, substances are combined. Under the influence of the concentrated force of gravity, the center of the nebula is compressed and stars are formed. Dust and gases are transformed into rings. The rings rotate under the influence of gravity, and planetasimals form in whirlpools, which increase and attract cosmetic objects to themselves.

Under the influence of the force of gravity, the planetazimals are compressed and acquire a spherical shape. Spheres can combine and gradually turn into protoplanets.



There are eight planets within the solar system. They revolve around the sun. Their location is:
The nearest “neighbor” of the Sun is Mercury, followed by Venus, then the Earth, then Mars and Jupiter, further from the Sun are Saturn, Uranus and the last one, Neptune.

SOLAR SYSTEM
The sun and the celestial bodies revolving around it - 9 planets, more than 63 satellites, four rings of giant planets, tens of thousands of asteroids, a myriad of meteoroids ranging in size from boulders to dust particles, as well as millions of comets. In the space between them moving particles of the solar wind - electrons and protons. The entire solar system has not yet been explored: for example, most of the planets and their satellites have only been briefly examined from flyby trajectories, only one hemisphere of Mercury has been photographed, and there have not yet been expeditions to Pluto. But still, with the help of telescopes and space probes, a lot of important data has already been collected.
Almost the entire mass of the solar system (99.87%) is concentrated in the Sun. The size of the Sun also greatly exceeds any planet in its system: even Jupiter, which is 11 times larger than the Earth, has a radius 10 times smaller than the sun. The sun is an ordinary star that shines on its own due to the high surface temperature. The planets, on the other hand, shine by reflected sunlight (albedo) because they themselves are quite cold. They are in the following order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Distances in the solar system are usually measured in units of the average distance of the Earth from the Sun, called the astronomical unit (1 AU = 149.6 million km). For example, the average distance of Pluto from the Sun is 39 AU, but sometimes it is removed by 49 AU. Comets are known to fly away at 50,000 AU. The distance from the Earth to the nearest star a Centaur is 272,000 AU, or 4.3 light years (that is, light moving at a speed of 299,793 km / s travels this distance in 4.3 years). For comparison, light travels from the Sun to the Earth in 8 minutes, and to Pluto in 6 hours.

The planets revolve around the Sun in almost circular orbits lying approximately in the same plane, in a counterclockwise direction, as viewed from the north pole of the Earth. The plane of the Earth's orbit (the plane of the ecliptic) lies close to the median plane of the orbits of the planets. Therefore, the visible paths of the planets, the Sun and the Moon in the sky pass near the line of the ecliptic, and they themselves are always visible against the background of the constellations of the Zodiac. Orbital inclinations are measured from the plane of the ecliptic. Tilt angles less than 90° correspond to forward orbital motion (counterclockwise), and angles greater than 90° correspond to reverse motion. All the planets in the solar system move in the forward direction; Pluto has the highest orbital inclination (17°). Many comets move in the opposite direction, for example, the orbital inclination of Halley's Comet is 162°. The orbits of all bodies in the solar system are very close to ellipses. The size and shape of an elliptical orbit are characterized by the semi-major axis of the ellipse (the average distance of the planet from the Sun) and the eccentricity, which varies from e = 0 for circular orbits to e = 1 for extremely elongated ones. The point in the orbit closest to the Sun is called perihelion, and the farthest point is called aphelion.
see also ORBIT ; CONIC SECTIONS . From the point of view of an earthly observer, the planets of the solar system are divided into two groups. Mercury and Venus, which are closer to the Sun than the Earth, are called the lower (inner) planets, and the more distant ones (from Mars to Pluto) are called the upper (external). The lower planets have a limiting angle of removal from the Sun: 28 ° for Mercury and 47 ° for Venus. When such a planet is as far as possible west (east) of the Sun, it is said to be at its greatest western (eastern) elongation. When an inferior planet is seen directly in front of the Sun, it is said to be in inferior conjunction; when directly behind the Sun - in superior conjunction. Like the Moon, these planets pass through all the phases of illumination by the Sun during the synodic period Ps, the time it takes the planet to return to its original position relative to the Sun from the point of view of an earthly observer. The true orbital period of a planet (P) is called sidereal. For the lower planets, these periods are related by the ratio:
1/Ps = 1/P - 1/Po where Po is the Earth's orbital period. For the upper planets, this ratio has a different form: 1/Ps = 1/Po - 1/P The upper planets are characterized by a limited range of phases. The maximum phase angle (Sun-planet-Earth) is 47° for Mars, 12° for Jupiter, and 6° for Saturn. When the upper planet is visible behind the Sun, it is in conjunction, and when in the opposite direction to the Sun, it is in opposition. A planet observed at an angular distance of 90° from the Sun is in quadrature (east or west). The asteroid belt, passing between the orbits of Mars and Jupiter, divides the planetary system of the Sun into two groups. Inside it are the terrestrial planets (Mercury, Venus, Earth and Mars), similar in that they are small, rocky and rather dense bodies: their average density is from 3.9 to 5.5 g / cm3. They rotate relatively slowly around their axes, lack rings and have few natural satellites: the Earth's Moon and the Martian Phobos and Deimos. Outside the asteroid belt are the giant planets: Jupiter, Saturn, Uranus and Neptune. They are characterized by large radii, low density (0.7-1.8 g/cm3) and deep atmospheres rich in hydrogen and helium. Jupiter, Saturn and possibly other giants do not have a solid surface. All of them rotate rapidly, have many satellites and are surrounded by rings. The distant little Pluto and the large satellites of the giant planets are in many ways similar to the terrestrial planets. Ancient people knew the planets visible to the naked eye, i.e. all internal and external up to Saturn. V. Herschel discovered Uranus in 1781. The first asteroid was discovered by J. Piazzi in 1801. Analyzing deviations in the motion of Uranus, W. Le Verrier and J. Adams theoretically discovered Neptune; at the calculated place it was discovered by I. Galle in 1846. The most distant planet - Pluto - was discovered in 1930 by K. Tombo as a result of a long search for a non-Neptunian planet organized by P. Lovell. Four large satellites of Jupiter were discovered by Galileo in 1610. Since then, with the help of telescopes and space probes, numerous satellites have been found for all outer planets. H. Huygens in 1656 established that Saturn is surrounded by a ring. The dark rings of Uranus were discovered from Earth in 1977 when observing the occultation of a star. The transparent stone rings of Jupiter were discovered in 1979 by the Voyager 1 interplanetary probe. Since 1983, at the moments of the occultation of the stars, signs of inhomogeneous rings have been noted near Neptune; in 1989 an image of these rings was transmitted by Voyager 2.
see also
ASTRONOMY AND ASTROPHYSICS;
ZODIAC;
SPACE PROBE ;
HEAVENLY SPHERE.
SUN
The Sun is located in the center of the solar system - a typical single star with a radius of about 700,000 km and a mass of 2 * 10 30 kg. The temperature of the visible surface of the Sun - the photosphere - approx. 5800 K. The density of gas in the photosphere is thousands of times less than the density of air near the Earth's surface. Inside the Sun, temperature, density and pressure increase with depth, reaching 16 million K, 160 g/cm3 and 3.5*10 11 bar in the center, respectively (the air pressure in the room is about 1 bar). Under the influence of high temperature in the core of the Sun, hydrogen is converted into helium with the release of a large amount of heat; this keeps the Sun from collapsing under its own gravity. The energy released in the core leaves the Sun mainly in the form of photosphere radiation with a power of 3.86 * 10 26 W. With such intensity, the Sun has been emitting for 4.6 billion years, having converted 4% of its hydrogen into helium during this time; at the same time, 0.03% of the mass of the Sun turned into energy. Models of stellar evolution indicate that the Sun is now in the middle of its life (see also NUCLEAR FUSION). To determine the abundance of various chemical elements on the Sun, astronomers study the absorption and emission lines in the spectrum of sunlight. Absorption lines are dark gaps in the spectrum, indicating the absence of photons of a given frequency in it, absorbed by a certain chemical element. Emission lines, or emission lines, are the brighter parts of the spectrum, indicating an excess of photons emitted by a chemical element. The frequency (wavelength) of a spectral line indicates which atom or molecule is responsible for its occurrence; the contrast of the line indicates the amount of light emitting or absorbing substance; the width of the line makes it possible to judge its temperature and pressure. The study of the thin (500 km) photosphere of the Sun makes it possible to estimate the chemical composition of its interior, since the outer regions of the Sun are well mixed by convection, the spectra of the Sun are of high quality, and the physical processes responsible for them are quite clear. However, it should be noted that only half of the lines in the solar spectrum have been identified so far. The composition of the Sun is dominated by hydrogen. In second place is helium, whose name ("helios" in Greek "Sun") recalls that it was discovered spectroscopically on the Sun earlier (1899) than on Earth. Since helium is an inert gas, it is extremely reluctant to react with other atoms and is also reluctant to show itself in the optical spectrum of the Sun - just one line, although many less abundant elements are represented in the spectrum of the Sun by numerous lines. Here is the composition of the "solar" substance: for 1 million hydrogen atoms there are 98,000 helium atoms, 851 oxygen, 398 carbon, 123 neon, 100 nitrogen, 47 iron, 38 magnesium, 35 silicon, 16 sulfur, 4 argon, 3 aluminum, according to 2 atoms of nickel, sodium and calcium, as well as a little bit of all other elements. Thus, by mass, the Sun is about 71% hydrogen and 28% helium; the remaining elements account for slightly more than 1%. From the point of view of planetology, it is noteworthy that some objects of the solar system have almost the same composition as the Sun (see the section on meteorites below). Just as weather events change the appearance of planetary atmospheres, the appearance of the sun's surface also changes with characteristic times ranging from hours to decades. However, there is an important difference between the atmospheres of the planets and the Sun, which is that the movement of gases on the Sun is controlled by its powerful magnetic field. Sunspots are those areas of the luminary's surface where the vertical magnetic field is so strong (200-3000 gauss) that it prevents the horizontal movement of gas and thereby suppresses convection. As a result, the temperature in this region drops by about 1000 K, and a dark central part of the spot appears - the "shadow", surrounded by a hotter transitional region - the "penumbra". The size of a typical sunspot is slightly larger than the Earth's diameter; there is such a spot for several weeks. The number of spots on the Sun either increases or decreases with the cycle duration from 7 to 17 years, averaging 11.1 years. Usually, the more spots appear in a cycle, the shorter the cycle itself. The direction of the magnetic polarity of the spots reverses from cycle to cycle, so the true cycle of sunspot activity is 22.2 years. At the beginning of each cycle, the first spots appear at high latitudes, ca. 40 °, and gradually the zone of their birth shifts to the equator to a latitude of approx. 5°. see also STARS ; SUN . Fluctuations in the activity of the Sun have almost no effect on the total power of its radiation (if it changed by only 1%, this would lead to serious climate changes on Earth). There have been many attempts to find a link between sunspot cycles and Earth's climate. The most remarkable event in this sense is the "Maunder minimum": from 1645 for 70 years there were almost no spots on the Sun, and at the same time the Earth experienced the Little Ice Age. It is still not clear whether this amazing fact mere coincidence or it indicates a causal relationship.
see also
CLIMATE;
METEOROLOGY AND CLIMATOLOGY. There are 5 huge rotating hydrogen-helium balls in the solar system: the Sun, Jupiter, Saturn, Uranus and Neptune. In the depths of these gigantic celestial bodies, inaccessible to direct research, almost all the matter of the solar system is concentrated. The Earth's interior is also inaccessible to us, but by measuring the propagation time of seismic waves (long-wavelength sound waves) excited in the body of the planet by earthquakes, seismologists compiled a detailed map of the Earth's interior: they learned the dimensions and densities of the Earth's core and its mantle, and also obtained three-dimensional images using seismic tomography. images of moving plates of its crust. Similar methods can be applied to the Sun, since there are waves on its surface with a period of approx. 5 minutes, caused by many seismic vibrations propagating in its bowels. These processes are studied by helioseismology. Unlike earthquakes, which produce short bursts of waves, vigorous convection in the interior of the Sun creates constant seismic noise. Helioseismologists have found that under the convective zone, which occupies the outer 14% of the Sun's radius, matter rotates synchronously with a period of 27 days (nothing is known about the rotation of the solar core yet). Above, in the convective zone itself, rotation occurs synchronously only along cones of equal latitude and the farther from the equator, the slower: the equatorial regions rotate with a period of 25 days (ahead of the average rotation of the Sun), and the polar regions - with a period of 36 days (lag behind the average rotation) . Recent attempts to apply seismological methods to gas giant planets have not yielded results, since instruments are not yet able to fix the resulting oscillations. Above the photosphere of the Sun is a thin hot layer of the atmosphere, which can be seen only in rare moments of solar eclipses. It is a chromosphere several thousand kilometers thick, so named for its red color due to the emission line of hydrogen Ha. The temperature almost doubles from the photosphere to the upper chromosphere, from which, for some unknown reason, the energy leaving the Sun is released as heat. Above the chromosphere, the gas is heated to 1 million K. This region, called the corona, extends for about 1 radius of the Sun. The gas density in the corona is very low, but the temperature is so high that the corona is a powerful source of X-rays. Sometimes giant formations appear in the atmosphere of the Sun - eruptive prominences. They look like arches rising from the photosphere to a height of up to half the solar radius. Observations clearly indicate that the shape of the prominences is determined by the magnetic field lines. Another interesting and extremely active phenomenon is solar flares, powerful ejections of energy and particles lasting up to two hours. The flow of photons generated by such a solar flare reaches the Earth at the speed of light in 8 minutes, and the flow of electrons and protons - in a few days. Solar flares occur in places where the direction of the magnetic field changes sharply, caused by the movement of matter in sunspots. The maximum flare activity of the Sun usually occurs a year before the maximum of the sunspot cycle. Such predictability is very important, because a flurry of charged particles born from a powerful solar flare can damage even ground-based communications and energy networks, not to mention astronauts and space technology.

SOLAR PROMINENTS observed in the helium emission line (wavelength 304) from the Skylab space station.

VENUS. An ultraviolet image taken from the Pioneer Venus interplanetary station shows the planet's atmosphere densely filled with clouds that are lighter in the polar regions (top and bottom of the image).

EARTH AND MOON from the Lunar Orbiter space probe.

SURFACE OF MARS near the landing block "Viking-1". Large fragments of stone have a size of about 30 cm.

SATURN and its moons, photographed during the passage of the Voyager space probe.

Universe (space)- this is the whole world around us, boundless in time and space and infinitely diverse in the forms that eternally moving matter takes. The boundlessness of the Universe can be partly imagined on a clear night with billions of different sizes of luminous flickering points in the sky, representing distant worlds. Rays of light at a speed of 300,000 km / s from the most distant parts of the universe reach the Earth in about 10 billion years.

According to scientists, the universe was formed as a result of the "Big Bang" 17 billion years ago.

It consists of clusters of stars, planets, cosmic dust and other cosmic bodies. These bodies form systems: planets with satellites (for example, the solar system), galaxies, metagalaxies (clusters of galaxies).

Galaxy(Late Greek galaktikos- milky, milky, from Greek gala- milk) is an extensive star system that consists of many stars, star clusters and associations, gas and dust nebulae, as well as individual atoms and particles scattered in interstellar space.

There are many galaxies in the universe of various sizes and shapes.

All stars visible from Earth are part of the Milky Way galaxy. It got its name due to the fact that most of the stars can be seen on a clear night in the form of the Milky Way - a whitish blurry band.

In total, the Milky Way Galaxy contains about 100 billion stars.

Our galaxy is in constant rotation. Its speed in the universe is 1.5 million km/h. If you look at our galaxy from its north pole, then the rotation occurs clockwise. The sun and the stars closest to it make a complete revolution around the center of the galaxy in 200 million years. This period is considered galactic year.

Similar in size and shape to the Milky Way galaxy is the Andromeda Galaxy, or the Andromeda Nebula, which is located at a distance of about 2 million light years from our galaxy. Light year- the distance traveled by light in a year, approximately equal to 10 13 km (the speed of light is 300,000 km / s).

To illustrate the study of the movement and location of stars, planets and other celestial bodies, the concept of the celestial sphere is used.

Rice. 1. The main lines of the celestial sphere

Celestial sphere is an imaginary sphere of arbitrarily large radius, in the center of which is the observer. Stars, the Sun, the Moon, planets are projected onto the celestial sphere.

The most important lines on the celestial sphere are: a plumb line, zenith, nadir, celestial equator, ecliptic, celestial meridian, etc. (Fig. 1).

plumb line- a straight line passing through the center of the celestial sphere and coinciding with the direction of the plumb line at the point of observation. For an observer on the surface of the Earth, a plumb line passes through the center of the Earth and the point of observation.

The plumb line intersects with the surface of the celestial sphere at two points - zenith, over the observer's head, and nadire - diametrically opposite point.

The great circle of the celestial sphere, the plane of which is perpendicular to the plumb line, is called mathematical horizon. It divides the surface of the celestial sphere into two halves: visible to the observer, with the apex at the zenith, and invisible, with the apex at the nadir.

The diameter around which the celestial sphere rotates is axis of the world. It intersects with the surface of the celestial sphere at two points - north pole of the world and south pole peace. The North Pole is the one from which the rotation of the celestial sphere occurs clockwise, if you look at the sphere from the outside.

The great circle of the celestial sphere, whose plane is perpendicular to the axis of the world, is called celestial equator. It divides the surface of the celestial sphere into two hemispheres: northern, with a peak at the north celestial pole, and south, with a peak at the south celestial pole.

The great circle of the celestial sphere, the plane of which passes through the plumb line and the axis of the world, is the celestial meridian. It divides the surface of the celestial sphere into two hemispheres - eastern and western.

The line of intersection of the plane of the celestial meridian and the plane of the mathematical horizon - noon line.

Ecliptic(from Greek. ekieipsis- Eclipse) - a large circle of the celestial sphere, along which the apparent annual movement of the Sun, or rather, its center, occurs.

The plane of the ecliptic is inclined to the plane of the celestial equator at an angle of 23°26"21".

To make it easier to remember the location of the stars in the sky, people in antiquity came up with the idea of ​​combining the brightest of them into constellations.

Currently, 88 constellations are known that bear the names of mythical characters (Hercules, Pegasus, etc.), zodiac signs (Taurus, Pisces, Cancer, etc.), objects (Libra, Lyra, etc.) (Fig. 2).

Rice. 2. Summer-autumn constellations

Origin of galaxies. The solar system and its individual planets still remains an unsolved mystery of nature. There are several hypotheses. It is currently believed that our galaxy formed from a gas cloud composed of hydrogen. At the initial stage of the evolution of the galaxy, the first stars formed from the interstellar gas-dust medium, and 4.6 billion years ago, the solar system.

Composition of the solar system

The set of celestial bodies moving around the Sun as a central body forms solar system. It is located almost on the outskirts of the Milky Way galaxy. The solar system is involved in rotation around the center of the galaxy. The speed of its movement is about 220 km / s. This movement occurs in the direction of the constellation Cygnus.

The composition of the solar system can be represented in the form of a simplified diagram shown in fig. 3.

Over 99.9% of the mass of the matter of the solar system falls on the Sun and only 0.1% - on all its other elements.

Rice. 3. Composition of the solar systems

Sun

Sun is a star, a giant hot ball. Its diameter is 109 times the diameter of the Earth, its mass is 330,000 times the mass of the Earth, but the average density is low - only 1.4 times the density of water. The sun is located at a distance of about 26,000 light years from the center of our galaxy and revolves around it, making one revolution in about 225-250 million years. The orbital speed of the Sun is 217 km/s, so it travels one light year in 1400 Earth years.

Rice. 4. The chemical composition of the Sun

The pressure on the Sun is 200 billion times higher than at the surface of the Earth. The density of solar matter and pressure rapidly increase in depth; the increase in pressure is explained by the weight of all overlying layers. The temperature on the surface of the Sun is 6000 K, and inside it is 13,500,000 K. The characteristic lifetime of a star like the Sun is 10 billion years.

Table 1. General information about the Sun

The chemical composition of the Sun is about the same as that of most other stars: about 75% is hydrogen, 25% is helium, and less than 1% is all other chemical elements (carbon, oxygen, nitrogen, etc.) (Fig. 4 ).

The central part of the Sun with a radius of approximately 150,000 km is called solar core. This is a nuclear reaction zone. The density of matter here is about 150 times higher than the density of water. The temperature exceeds 10 million K (on the Kelvin scale, in terms of degrees Celsius 1 ° C \u003d K - 273.1) (Fig. 5).

Above the core, at distances of about 0.2-0.7 of the radius of the Sun from its center, there is radiant energy transfer zone. Energy transfer here is carried out by absorption and emission of photons by individual layers of particles (see Fig. 5).

Rice. 5. Structure of the Sun

Photon(from Greek. phos- light), an elementary particle that can exist only by moving at the speed of light.

Closer to the surface of the Sun, vortex mixing of the plasma occurs, and the energy transfer to the surface occurs

predominantly by the movements of the substance itself. This type of energy transfer is called convection and the layer of the Sun, where it occurs, - convective zone. The thickness of this layer is approximately 200,000 km.

Above the convective zone is the solar atmosphere, which is constantly fluctuating. Both vertical and horizontal waves with lengths of several thousand kilometers propagate here. The oscillations occur with a period of about five minutes.

The inner layer of the sun's atmosphere is called photosphere. It consists of light bubbles. it granules. Their dimensions are small - 1000-2000 km, and the distance between them is 300-600 km. About a million granules can be simultaneously observed on the Sun, each of which exists for several minutes. The granules are surrounded by dark spaces. If the substance rises in the granules, then around them it falls. Granules create general background, where you can observe such large-scale formations as torches, sunspots, prominences, etc.

sunspots- dark areas on the Sun, the temperature of which is lowered compared to the surrounding space.

solar torches called the bright fields surrounding sunspots.

prominences(from lat. protubero- I swell) - dense condensations of relatively cold (compared to the ambient temperature) matter that rise and are held above the surface of the Sun by a magnetic field. The origin of the magnetic field of the Sun can be caused by the fact that different layers of the Sun rotate at different speeds: the inner parts rotate faster; the core rotates especially fast.

Prominences, sunspots, and flares are not the only examples of solar activity. It also includes magnetic storms and explosions, which are called flashes.

Above the photosphere is chromosphere is the outer shell of the sun. The origin of the name of this part of the solar atmosphere is associated with its reddish color. The thickness of the chromosphere is 10-15 thousand km, and the density of matter is hundreds of thousands of times less than in the photosphere. The temperature in the chromosphere is growing rapidly, reaching tens of thousands of degrees in its upper layers. At the edge of the chromosphere are observed spicules, which are elongated columns of compacted luminous gas. The temperature of these jets is higher than the temperature of the photosphere. Spicules first rise from the lower chromosphere by 5000-10000 km, and then fall back, where they fade. All this happens at a speed of about 20,000 m/s. Spikula lives 5-10 minutes. The number of spicules existing on the Sun at the same time is about a million (Fig. 6).

Rice. 6. The structure of the outer layers of the Sun

The chromosphere surrounds solar corona is the outer layer of the sun's atmosphere.

The total amount of energy radiated by the Sun is 3.86. 1026 W, and only one two billionth of this energy is received by the Earth.

Solar radiation includes corpuscular and electromagnetic radiation.Corpuscular fundamental radiation- this is a plasma stream, which consists of protons and neutrons, or in other words - sunny wind, which reaches near-Earth space and flows around the entire Earth's magnetosphere. electromagnetic radiation is the radiant energy of the sun. It reaches the earth's surface in the form of direct and scattered radiation and provides a thermal regime on our planet.

In the middle of the XIX century. Swiss astronomer Rudolf Wolf(1816-1893) (Fig. 7) calculated quantitative indicator solar activity, known worldwide as the Wolf number. Having processed the data on observations of sunspots accumulated by the middle of the last century, Wolf was able to establish the average 1-year cycle of solar activity. In fact, the time intervals between years of maximum or minimum Wolf numbers range from 7 to 17 years. Simultaneously with the 11-year cycle, a secular, more precisely 80-90-year cycle of solar activity takes place. Inconsistently superimposed on each other, they make noticeable changes in the processes taking place in the geographic envelope of the Earth.

A. L. Chizhevsky (1897-1964) (Fig. 8) pointed out the close connection of many terrestrial phenomena with solar activity back in 1936, who wrote that the vast majority of physical and chemical processes on Earth are the result of the influence of cosmic forces. He was also one of the founders of such a science as heliobiology(from Greek. helios- the sun), studying the influence of the Sun on living matter geographical envelope Earth.

Depending on solar activity, such physical phenomena occur on Earth, such as: magnetic storms, the frequency of auroras, the amount of ultraviolet radiation, the intensity of thunderstorm activity, air temperature, atmospheric pressure, precipitation, the level of lakes, rivers, groundwater, salinity and efficiency of the seas and others

The life of plants and animals is associated with the periodic activity of the Sun (there is a correlation between the solar cycle and the period of the growing season in plants, the reproduction and migration of birds, rodents, etc.), as well as humans (diseases).

At present, the relationship between solar and terrestrial processes continues to be studied using artificial satellites Earth.

terrestrial planets

In addition to the Sun, planets are distinguished in the Solar System (Fig. 9).

By size, geographical indicators and chemical composition, the planets are divided into two groups: terrestrial planets and giant planets. The terrestrial planets include, and. They will be discussed in this subsection.

Rice. 9. Planets of the solar system

Earth is the third planet from the Sun. A separate section will be devoted to it.

Let's summarize. The density of the matter of the planet depends on the location of the planet in the solar system, and, taking into account its size, the mass. How
The closer the planet is to the Sun, the higher its average density of matter. For example, for Mercury it is 5.42 g/cm2, Venus - 5.25, Earth - 5.25, Mars - 3.97 g/cm 3 .

The general characteristics of the terrestrial planets (Mercury, Venus, Earth, Mars) are primarily: 1) relatively small sizes; 2) high temperatures on the surface and 3) the high density of the matter of the planets. These planets rotate relatively slowly on their axis and have few or no satellites. In the structure of the planets of the terrestrial group, four main shells are distinguished: 1) a dense core; 2) the mantle covering it; 3) bark; 4) light gas-water shell (excluding Mercury). Traces of tectonic activity have been found on the surface of these planets.

giant planets

Now let's get acquainted with the giant planets, which are also included in our solar system. It , .

Giant planets have the following general characteristics: 1) large size and mass; 2) quickly rotate around an axis; 3) have rings, many satellites; 4) the atmosphere consists mainly of hydrogen and helium; 5) have a hot core of metals and silicates in the center.

They are also distinguished by: 1) low surface temperatures; 2) low density of matter of the planets.

Venus


The second planet from the Sun, has an almost circular orbit. It passes closer to Earth than any other planet. But the dense, cloudy atmosphere does not allow you to directly see its surface. Atmosphere: CO 2 (97%), N2 (approx. 3%), H 2 O (0.05%), impurities CO, SO 2, HCl, HF. Due to the greenhouse effect, the surface temperature warms up to hundreds of degrees. The atmosphere, which is a dense blanket of carbon dioxide, traps the heat that comes from the Sun. This leads to the fact that the temperature of the atmosphere is much higher than in the oven. Radar images show a very wide variety of craters, volcanoes and mountains. There are several very large volcanoes, up to 3 km high. and hundreds of kilometers wide. The outpouring of lava on Venus takes much longer than on Earth. The surface pressure is about 107 Pa. The surface rocks of Venus are similar in composition to terrestrial sedimentary rocks.
Finding Venus in the sky is easier than any other planet. Its dense clouds reflect well sunlight, making the planet bright in our sky. Every seven months for several weeks, Venus is the brightest object in the western sky in the evening. Three and a half months later, it rises three hours before the Sun, becoming the brilliant "morning star" of the eastern sky. Venus can be observed an hour after sunset or an hour before sunrise. Venus has no satellites.

Earth .

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is the third planet from the Sun. The speed of the Earth's circulation in an elliptical orbit around the Sun is - 29.765 km / s. The inclination of the earth's axis to the plane of the ecliptic is 66 o 33 "22"". The Earth has a natural satellite -. The Earth has a magnetic and electric fields. The Earth was formed 4.7 billion years ago from the gas-dust substance scattered in the protosolar system. The composition of the Earth is dominated by: iron (34.6%), oxygen (29.5%), silicon (15.2%), magnesium (12.7%). The pressure in the center of the planet is 3.6 * 10 11 Pa, the density is about 12,500 kg / m 3, the temperature is 5000-6000 o C. Most of the surface is occupied by the World Ocean (361.1 million km 2; 70.8%); land is 149.1 million km 2 and forms six continents and islands. It rises above the level of the world ocean by an average of 875 meters (the highest height is 8848 meters - the city of Chomolungma). Mountains occupy 30% of the land, deserts cover about 20% of the land surface, savannas and light forests - about 20%, forests - about 30%, glaciers - 10%. The average depth of the ocean is about 3800 meters, the greatest is 11022 meters (the Mariana Trench in the Pacific Ocean), the volume of water is 1370 million km 3, the average salinity is 35 g / l. The atmosphere of the Earth, the total mass of which is 5.15 * 10 15 tons, consists of air - a mixture of mainly nitrogen (78.1%) and oxygen (21%), the rest is water vapor, carbon dioxide, noble and other gases. About 3-3.5 billion years ago, as a result of the natural evolution of matter, life arose on Earth, and the development of the biosphere began.

Mars .

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the fourth planet from the Sun, similar to Earth, but smaller and colder. Mars has deep canyons, giant volcanoes, and vast deserts. Around the Red Planet, as Mars is also called, two small moons fly: Phobos and Deimos. Mars is the planet next to the Earth, if you count from the Sun, and the only space world, apart from the Moon, that can already be reached with modern rockets. For astronauts, this four-year journey could be the next frontier in space exploration. Near the equator of Mars, in the region called Tharsis, there are volcanoes of colossal proportions. Tarsis is the name that astronomers gave to a hill that has 400 km. wide and about 10 km. in height. There are four volcanoes on this plateau, each of which is simply a giant in comparison with any terrestrial volcano. The most grandiose volcano of Tarsis, Mount Olympus, rises above the surrounding area for 27 km. About two-thirds of the surface of Mars is highlands with a large number of impact craters and surrounded by hard rock fragments. Near the volcanoes of Tharsis snakes a vast system of canyons about a quarter of the equator long. The Mariner Valley is 600 km wide, and its depth is such that Mount Everest would sink entirely to its bottom. Sheer cliffs rise thousands of meters, from the bottom of the valley to the plateau above. In ancient times, there was a lot of water on Mars, large rivers flowed on the surface of this planet. Ice caps lie at the South and North Poles of Mars. But this ice does not consist of water, but of frozen atmospheric carbon dioxide (it freezes at a temperature of -100 o C). Scientists believe that surface water is stored in the form of ice blocks buried in the ground, especially in the polar regions. Atmospheric composition: CO 2 (95%), N 2 (2.5%), Ar (1.5 - 2%), CO (0.06%), H 2 O (up to 0.1%); pressure near the surface is 5-7 hPa. In total, about 30 interplanetary space stations were sent to Mars.

Jupiter - the largest planet.

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- the fifth planet from the Sun, the largest planet in the solar system. Jupiter is not a solid planet. Unlike the four solid planets closest to the Sun, Jupiter is a gas ball. The composition of the atmosphere: H 2 (85%), CH 4 , NH 3 , He (14%). Jupiter's gas composition is very similar to that of the sun. Jupiter is a powerful source of thermal radio emission. Jupiter has 16 satellites (Adrastea, Metis, Amalthea, Thebe, Io, Lysitea, Elara, Ananke, Karma, Pasiphe, Sinope, Europa, Ganymede, Callisto, Leda, Himalia), as well as a ring 20,000 km wide, almost closely adjacent to planet. Jupiter's rotation speed is so great that the planet bulges along the equator. In addition, such a rapid rotation causes very strong winds in the upper atmosphere, where the clouds are stretched out in long colorful ribbons. There are a very large number of vortex spots in the clouds of Jupiter. The largest of them, the so-called Great Red Spot, is larger than the Earth. The Great Red Spot is a huge storm in Jupiter's atmosphere that has been observed for 300 years. Inside the planet, under enormous pressure, hydrogen from a gas turns into a liquid, and then from a liquid into solid. At a depth of 100 km. there is a vast ocean of liquid hydrogen. Below 17000 km. hydrogen is compressed so strongly that its atoms are destroyed. And then it starts behaving like metal; in this state, it easily conducts electricity. An electric current flowing in metallic hydrogen creates a strong magnetic field around Jupiter.

Saturn .

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the sixth planet from the Sun, has a striking system of rings. Due to the rapid rotation around its axis, Saturn seems to be flattened at the poles. The wind speed at the equator reaches 1800 km/h. The rings of Saturn are 400,000 km wide, but they are only a few tens of meters thick. The inner parts of the rings revolve around Saturn faster than the outer ones. The rings are mostly made up of billions of small particles, each of which orbits Saturn as a separate microscopic satellite. Probably, these "microsatellites" consist of water ice or rocks covered with ice. Their size ranges from a few centimeters to tens of meters. There are also larger objects in the rings - stone blocks and fragments up to hundreds of meters in diameter. The gaps between the rings arise under the influence of the gravitational forces of seventeen moons (Hyperion, Mimas, Tethys, Titan, Enceladus, etc.), which cause the rings to split. The composition of the atmosphere includes: CH 4 , H 2 , He, NH 3 .

Uranus .

is the seventh planet from the Sun. It was discovered in 1781 by the English astronomer William Herschel and named after the Greek sky god Uranus. The orientation of Uranus in space differs from the rest of the planets of the solar system - its axis of rotation lies, as it were, "on its side" relative to the plane of revolution of this planet around the Sun. The axis of rotation is inclined at an angle of 98 o . As a result, the planet is turned to the Sun alternately with the north pole, then the south, then the equator, then the middle latitudes. Uranus has more than 27 satellites (Miranda, Ariel, Umbriel, Titania, Oberon, Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Pack, etc.) and a system of rings. At the center of Uranus is a core composed of stone and iron. The composition of the atmosphere includes: H 2 , He, CH 4 (14%).

Neptune .

- its orbit intersects with the orbit of Pluto in some places. The equatorial diameter is the same as that of Uranus, although Neptune is located 1627 million km further from Uranus (Uranus is located 2869 million km from the Sun). Based on these data, we can conclude that this planet could not be noticed in the 17th century. One of the striking achievements of science, one of the evidence of the unlimited cognizability of nature was the discovery of the planet Neptune by calculations - "on the tip of a pen." Uranus - the planet following Saturn, which for many centuries was considered the most distant planet, was discovered by V. Herschel at the end of the 18th century. Uranus is hardly visible to the naked eye. By the 40s of the XIX century. accurate observations have shown that Uranus deviates just barely from the path it should follow, given the perturbations from all the known planets. Thus the theory of motion of celestial bodies, so rigorous and precise, was put to the test. Le Verrier (in France) and Adams (in England) suggested that if perturbations from the known planets do not explain the deviation in the motion of Uranus, it means that the attraction of an as yet unknown body acts on it. They almost simultaneously calculated where behind Uranus there should be an unknown body that produces these deviations by its attraction. They calculated the orbit of the unknown planet, its mass and indicated the place in the sky where the unknown planet should have been at the given time. This planet was found in a telescope at the place indicated by them in 1846. It was called Neptune. Neptune is not visible to the naked eye. On this planet, winds blow at speeds up to 2400 km / h, directed against the rotation of the planet. These are the strongest winds in the solar system.
Atmospheric composition: H 2 , He, CH 4 . It has 6 satellites (one of them is Triton).
Neptune is the god of the seas in Roman mythology.

The planets in the solar system, as you can see from the descriptions, are all different from each other. Scientists also find planets around other stars, they are called exoplanets.

Sources:
www.kosmos19.narod.ru
www.ggreen.chat.ru
http://en.wikipedia.org