This is a system of planets, in the center of which there is a bright star, a source of energy, heat and light - the Sun.
According to one theory, the Sun was formed along with the Solar System about 4.5 billion years ago as a result of the explosion of one or more supernovae. Initially, the Solar System was a cloud of gas and dust particles, which, in motion and under the influence of their mass, formed a disk in which a new star, the Sun, and our entire Solar System arose.
At the center of the solar system is the Sun, around which nine large planets revolve in orbit. Since the Sun is displaced from the center of planetary orbits, during the cycle of revolution around the Sun the planets either approach or move away in their orbits.
There are two groups of planets:
Terrestrial planets: And . These planets are small in size with a rocky surface and are closest to the Sun.
Giant planets: And . These are large planets, consisting mainly of gas and characterized by the presence of rings consisting of icy dust and many rocky chunks.
And here does not fall into any group, because, despite its location in the solar system, it is located too far from the Sun and has a very small diameter, only 2320 km, which is half the diameter of Mercury.
Planets of the Solar System
Let's begin a fascinating acquaintance with the planets of the Solar System in order of their location from the Sun, and also consider their main satellites and some other space objects (comets, asteroids, meteorites) in the gigantic expanses of our planetary system.
Rings and moons of Jupiter: Europa, Io, Ganymede, Callisto and others...
The planet Jupiter is surrounded by a whole family of 16 satellites, and each of them has its own unique features...
Rings and moons of Saturn: Titan, Enceladus and others...
Not only the planet Saturn has characteristic rings, but also other giant planets. Around Saturn, the rings are especially clearly visible, because they consist of billions of small particles that revolve around the planet, in addition to several rings, Saturn has 18 satellites, one of which is Titan, its diameter is 5000 km, which makes it the largest satellite in the solar system...
Rings and moons of Uranus: Titania, Oberon and others...
The planet Uranus has 17 satellites and, like other giant planets, there are thin rings surrounding the planet that have practically no ability to reflect light, so they were discovered not so long ago in 1977, completely by accident...
Rings and moons of Neptune: 
Triton, Nereid and others...
Initially, before the exploration of Neptune by the Voyager 2 spacecraft, two satellites of the planet were known - Triton and Nerida. An interesting fact is that the Triton satellite has a reverse direction of orbital motion; strange volcanoes were also discovered on the satellite that erupted nitrogen gas like geysers, spreading a dark-colored mass (from liquid to vapor) many kilometers into the atmosphere. During its mission, Voyager 2 discovered six more moons of the planet Neptune...
Planets of the Solar System
According to the official position of the International Astronomical Union (IAU), the organization that assigns names to astronomical objects, there are only 8 planets.
Pluto was removed from the planet category in 2006. because There are objects in the Kuiper belt that are larger/equal in size to Pluto. Therefore, even if we take it as a full-fledged celestial body, then it is necessary to add Eris to this category, which has almost the same size as Pluto.
By MAC definition, there are 8 known planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
All planets are divided into two categories depending on their physical characteristics: terrestrial planets and gas giants.
Schematic representation of the location of the planets
Terrestrial planets
Mercury
The smallest planet in the solar system has a radius of only 2440 km. The period of revolution around the Sun, equated to an earthly year for ease of understanding, is 88 days, while Mercury manages to rotate around its own axis only one and a half times. Thus, his day lasts approximately 59 Earth days. For a long time it was believed that this planet always turned the same side to the Sun, since periods of its visibility from Earth were repeated with a frequency approximately equal to four Mercury days. This misconception was dispelled with the advent of the ability to use radar research and conduct continuous observations using space stations. The orbit of Mercury is one of the most unstable; not only the speed of movement and its distance from the Sun change, but also the position itself. Anyone interested can observe this effect.
Mercury in color, image from the MESSENGER spacecraft
Its proximity to the Sun is the reason why Mercury is subject to the largest temperature changes among the planets in our system. The average daytime temperature is about 350 degrees Celsius, and the nighttime temperature is -170 °C. Sodium, oxygen, helium, potassium, hydrogen and argon were detected in the atmosphere. There is a theory that it was previously a satellite of Venus, but so far this remains unproven. It does not have its own satellites.
Venus
The second planet from the Sun, the atmosphere is almost entirely composed of carbon dioxide. It is often called the Morning Star and the Evening Star, because it is the first of the stars to become visible after sunset, just as before dawn it continues to be visible even when all the other stars have disappeared from view. The percentage of carbon dioxide in the atmosphere is 96%, there is relatively little nitrogen in it - almost 4%, and water vapor and oxygen are present in very small quantities.
Venus in the UV spectrum
Such an atmosphere creates a greenhouse effect; the temperature on the surface is even higher than that of Mercury and reaches 475 °C. Considered the slowest, a Venusian day lasts 243 Earth days, which is almost equal to a year on Venus - 225 Earth days. Many call it Earth's sister because of its mass and radius, the values of which are very close to those of Earth. The radius of Venus is 6052 km (0.85% of Earth's). Like Mercury, there are no satellites.
The third planet from the Sun and the only one in our system where there is liquid water on the surface, without which life on the planet could not have developed. At least life as we know it. The radius of the Earth is 6371 km and, unlike other celestial bodies in our system, more than 70% of its surface is covered with water. The rest of the space is occupied by continents. Another feature of the Earth is the tectonic plates hidden under the planet's mantle. At the same time, they are able to move, albeit at a very low speed, which over time causes changes in the landscape. The speed of the planet moving along it is 29-30 km/sec.
Our planet from space
One revolution around its axis takes almost 24 hours, and a complete passage through the orbit lasts 365 days, which is much longer in comparison with its closest neighboring planets. The Earth's day and year are also accepted as a standard, but this is done only for the convenience of perceiving time periods on other planets. The Earth has one natural satellite - the Moon.
Mars
The fourth planet from the Sun, known for its thin atmosphere. Since 1960, Mars has been actively explored by scientists from several countries, including the USSR and the USA. Not all exploration programs have been successful, but water found at some sites suggests that primitive life exists on Mars, or existed in the past.
The brightness of this planet allows it to be seen from Earth without any instruments. Moreover, once every 15-17 years, during the Confrontation, it becomes the brightest object in the sky, eclipsing even Jupiter and Venus.
The radius is almost half that of Earth and is 3390 km, but the year is much longer - 687 days. He has 2 satellites - Phobos and Deimos .
Visual model of the solar system
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Sun
The Sun is a star, which is a hot ball of hot gases at the center of our Solar System. Its influence extends far beyond the orbits of Neptune and Pluto. Without the Sun and its intense energy and heat, there would be no life on Earth. There are billions of stars like our Sun scattered throughout the Milky Way galaxy.
Mercury
Sun-scorched Mercury is only slightly larger than Earth's satellite the Moon. Like the Moon, Mercury is practically devoid of an atmosphere and cannot smooth out the traces of impact from falling meteorites, so it, like the Moon, is covered with craters. The day side of Mercury gets very hot from the Sun, while on the night side the temperature drops hundreds of degrees below zero. There is ice in the craters of Mercury, which are located at the poles. Mercury completes one revolution around the Sun every 88 days.
Venus
Venus is a world of monstrous heat (even more than on Mercury) and volcanic activity. Similar in structure and size to Earth, Venus is covered by a thick and toxic atmosphere that creates a strong greenhouse effect. This scorched world is hot enough to melt lead. Radar images through the powerful atmosphere revealed volcanoes and deformed mountains. Venus rotates in the opposite direction from the rotation of most planets.
Earth is an ocean planet. Our home, with its abundance of water and life, makes it unique in our solar system. Other planets, including several moons, also have ice deposits, atmospheres, seasons and even weather, but only on Earth did all these components come together in a way that made life possible.
Mars
Although details of the surface of Mars are difficult to see from Earth, observations through a telescope indicate that Mars has seasons and white spots at the poles. For decades, people believed that the bright and dark areas on Mars were patches of vegetation, that Mars might be a suitable place for life, and that water existed in the polar ice caps. When the Mariner 4 spacecraft arrived at Mars in 1965, many scientists were shocked to see photographs of the murky, cratered planet. Mars turned out to be a dead planet. More recent missions, however, have revealed that Mars holds many mysteries that remain to be solved.
Jupiter
Jupiter is the most massive planet in our solar system, with four large moons and many small moons. Jupiter forms a kind of miniature solar system. To become a full-fledged star, Jupiter needed to become 80 times more massive.
Saturn
Saturn is the farthest of the five planets known before the invention of the telescope. Like Jupiter, Saturn is composed primarily of hydrogen and helium. Its volume is 755 times greater than that of the Earth. Winds in its atmosphere reach speeds of 500 meters per second. These fast winds, combined with heat rising from the planet's interior, cause the yellow and golden streaks we see in the atmosphere.
Uranus
The first planet found using a telescope, Uranus was discovered in 1781 by astronomer William Herschel. The seventh planet is so far from the Sun that one revolution around the Sun takes 84 years.
Neptune
Distant Neptune rotates almost 4.5 billion kilometers from the Sun. It takes him 165 years to complete one revolution around the Sun. It is invisible to the naked eye due to its vast distance from Earth. Interestingly, its unusual elliptical orbit intersects with the orbit of the dwarf planet Pluto, which is why Pluto is inside the orbit of Neptune for about 20 years out of 248 during which it makes one revolution around the Sun.
Pluto
Tiny, cold and incredibly distant, Pluto was discovered in 1930 and was long considered the ninth planet. But after discoveries of Pluto-like worlds that were even further away, Pluto was reclassified as a dwarf planet in 2006.
Planets are giants
There are four gas giants located beyond the orbit of Mars: Jupiter, Saturn, Uranus, Neptune. They are located in the outer solar system. They are distinguished by their massiveness and gas composition.
Planets of the solar system, not to scale
Jupiter
The fifth planet from the Sun and the largest planet in our system. Its radius is 69912 km, it is 19 times larger than the Earth and only 10 times smaller than the Sun. The year on Jupiter is not the longest in the solar system, lasting 4333 Earth days (less than 12 years). His own day has a duration of about 10 Earth hours. The exact composition of the planet's surface has not yet been determined, but it is known that krypton, argon and xenon are present on Jupiter in much larger quantities than on the Sun.
There is an opinion that one of the four gas giants is actually a failed star. This theory is also supported by the largest number of satellites, of which Jupiter has many - as many as 67. To imagine their behavior in the planet’s orbit, you need a fairly accurate and clear model of the solar system. The largest of them are Callisto, Ganymede, Io and Europa. Moreover, Ganymede is the largest satellite of the planets in the entire solar system, its radius is 2634 km, which is 8% greater than the size of Mercury, the smallest planet in our system. Io has the distinction of being one of only three moons with an atmosphere.
Saturn
The second largest planet and the sixth in the solar system. In comparison with other planets, it is most similar to the Sun in the composition of chemical elements. The radius of the surface is 57,350 km, the year is 10,759 days (almost 30 Earth years). A day here lasts a little longer than on Jupiter - 10.5 Earth hours. In terms of the number of satellites, it is not much behind its neighbor - 62 versus 67. The largest satellite of Saturn is Titan, just like Io, which is distinguished by the presence of an atmosphere. Slightly smaller in size, but no less famous are Enceladus, Rhea, Dione, Tethys, Iapetus and Mimas. It is these satellites that are the objects for the most frequent observation, and therefore we can say that they are the most studied in comparison with the others.
For a long time, the rings on Saturn were considered a unique phenomenon unique to it. Only recently it was established that all gas giants have rings, but in others they are not so clearly visible. Their origin has not yet been established, although there are several hypotheses about how they appeared. In addition, it was recently discovered that Rhea, one of the satellites of the sixth planet, also has some kind of rings.
Our Earth is one of the 8 major planets revolving around the Sun. It is in the Sun that the bulk of the matter in the Solar System is concentrated. The mass of the Sun is 750 times the mass of all the planets and 330,000 times the mass of the Earth. Under the influence of its gravity, the planets and all other bodies of the solar system move around the Sun.
The distances between the Sun and the planets are many times greater than their sizes, and it is almost impossible to draw a diagram that would maintain a single scale for the Sun, planets and the distances between them. The diameter of the Sun is 109 times greater than that of the Earth, and the distance between them is approximately the same number of times greater than the diameter of the Sun. In addition, the distance from the Sun to the last planet of the solar system (Neptune) is 30 times greater than the distance to Earth. If we depict our planet as a circle with a diameter of 1 mm, then the Sun will be at a distance of about 11 m from the Earth, and its diameter will be approximately 11 cm. The orbit of Neptune will be shown as a circle with a radius of 330 m. Therefore, they usually do not give a modern diagram of the Solar system, but only a drawing from Copernicus’s book “On the Revolution of the Heavenly Circles” with other, very approximate proportions.
According to their physical characteristics, large planets are divided into two groups. One of them - terrestrial planets- consists of the Earth and similar Mercury, Venus and Mars. The second includes giant planets: Jupiter, Saturn, Uranus and Neptune (Table 1).
Table 1
Location and physical characteristics of major planets
Until 2006, Pluto was considered the largest planet farthest from the Sun. Now it, together with other objects of similar size - long-known large asteroids (see § 4) and objects discovered on the outskirts of the Solar system - is one of the dwarf planets.
The division of planets into groups can be traced according to three characteristics (mass, pressure, rotation), but most clearly - according to density. Planets belonging to the same group differ only slightly in density, while the average density of terrestrial planets is approximately 5 times greater than the average density of giant planets (see Table 1).
Most of the mass terrestrial planets accounts for the share of solids. The Earth and other terrestrial planets consist of oxides and other compounds of heavy chemical elements: iron, magnesium, aluminum and other metals, as well as silicon and other non-metals. The four most abundant elements in the solid shell of our planet (lithosphere) - iron, oxygen, silicon and magnesium - account for over 90% of its mass.
Low density giant planets(for Saturn it is less than the density of water) is explained by the fact that they consist mainly of hydrogen and helium, which are predominantly in gaseous and liquid states. The atmospheres of these planets also contain hydrogen compounds - methane and ammonia. Differences between the planets of the two groups arose already at the stage of their formation (see § 5).
Of the giant planets, Jupiter is the best studied, on which even with a small school telescope numerous dark and light stripes are visible, stretching parallel to the planet’s equator. This is what cloud formations look like in its atmosphere, the temperature of which is only -140 °C, and the pressure is approximately the same as at the surface of the Earth. The reddish-brown color of the stripes is apparently explained by the fact that, in addition to the ammonia crystals that form the basis of the clouds, they contain various impurities. Images taken by spacecraft show traces of intense and sometimes persistent atmospheric processes. Thus, for over 350 years, an atmospheric vortex has been observed on Jupiter, called the Great Red Spot. In the earth's atmosphere, cyclones and anticyclones exist on average for about a week. Atmospheric currents and clouds have been recorded by spacecraft on other giant planets, although they are less developed than on Jupiter.
Structure. It is assumed that as it approaches the center of the giant planets, hydrogen, due to increasing pressure, should pass from a gaseous to a gas-liquid state, in which its gaseous and liquid phases coexist. At the center of Jupiter, the pressure is millions of times higher than the atmospheric pressure that exists on Earth, and hydrogen acquires properties characteristic of metals. In the interior of Jupiter, metallic hydrogen, together with silicates and metals, forms a core that is approximately 1.5 times larger in size and 10-15 times larger in mass than the Earth.
Weight. Any of the giant planets exceeds in mass all the terrestrial planets combined. The largest planet in the solar system, Jupiter, is 11 times larger in diameter and more than 300 times larger in mass than the largest terrestrial planet, Earth.
Rotation. The differences between the planets of the two groups are manifested both in the fact that the giant planets rotate faster around their axis and in the number of satellites: for 4 terrestrial planets there are only 3 satellites, for 4 giant planets - more than 120. All these satellites consist of the same substances like terrestrial planets - silicates, oxides and sulfides of metals, etc., as well as water (or water-ammonia) ice. In addition to numerous craters of meteorite origin, tectonic faults and cracks in their crust or ice cover were discovered on the surface of many satellites. The most surprising thing was the discovery of about a dozen active volcanoes on the closest moon to Jupiter, Io. This is the first reliable observation of terrestrial-type volcanic activity outside our planet.
In addition to satellites, giant planets also have rings, which are clusters of small-sized bodies. They are so small that they are not visible individually. Thanks to their orbit around the planet, the rings appear solid, although through the rings of Saturn, for example, both the surface of the planet and the stars are visible. The rings are located in close proximity to the planet, where large satellites cannot exist.
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1. Earth - planet of the solar system§ 2. Terrestrial planets. Earth-moon system
Scientists believe that the formation of the solar system began about five billion years ago. According to the generally accepted existing theory, the Earth and its surrounding planets were formed from cosmic dust located in the vicinity of the Sun. According to assumptions, the dust particles consisted of iron and nickel atoms, as well as silicates. The gases present near the dust were also subject to condensation, forming carbonaceous substances. Later, nitrogenous substances and hydrocarbons appeared.
Structure of the Solar System: hypotheses
A well-known hypothesis for the origin of our Solar System is the electromagnetic theory, which is based on the assumption of scientists that the Sun once had a powerful electromagnetic field, and the nebula surrounding the star consisted of neutrally charged atoms. As a result of radiation and collisions, ionization of particles occurred, which fell into traps from magnetic force lines and were sent after the star. After many years, the Sun began to lose its angular momentum, transferring it to a cloud of gas from which planets began to form.
However, this theory is unlikely. Essentially, the atoms of light substances should have been ionized closer to the Sun, and heavy metals - further. And the result would be that the planets closest to the star would have to consist of the lightest chemical elements - helium and hydrogen, and the distant ones - of nickel and iron. However, today one can see the opposite picture.
To get rid of the contradiction, a new hypothesis was created, indicating that the Sun began to emerge in the depths of the nebula. The star rotated very quickly, and the nebula gradually became flatter and flatter until it turned into a disk. After a certain period, it acquired acceleration, and the Sun, on the contrary, slowed down. After this, processes began to occur in the disk, as a result of which the formation of the Solar System began.
A well-known hypothesis for the birth of planets is the theory about the emergence of the Solar system from a cold cloud of gas and dust surrounding the Sun.
Structure of the Solar System: Planets
Today it is believed that the solar system consists of the sun and eight planets. According to their physical characteristics, celestial objects can be classified into two types. One group includes the Earth and planets similar to it - Mars, Venus, Mercury. The second includes such giant planets of the solar system as Neptune, Uranus,
Planets are divided according to three characteristics: mass, density and size. The average density of planets belonging to the terrestrial group is five times higher than that of the giant planets. The structure of the Solar System indicates that the terrestrial objects closest to the Sun contain oxides and heavy compounds of chemical elements: aluminum, magnesium, iron, silicon, as well as non-metals. The low density of giants is explained by their structure. They are in a liquid or gaseous state and contain mostly hydrogen or helium.
However, the structure of the Solar system shows that any of the giant planets exceeds in mass all the celestial objects of the terrestrial group taken together. All giants have extensive, powerful atmospheres that consist of molecular hydrogen and contain ammonia, methane, helium and water. The remaining substances make up no more than one percent of their mass. In their composition, giant planets are similar to other stars, and primarily to the Sun.
Atmospheric hydrogen can change from gaseous to liquid, and even solid. The compression of the giants is due to the speed of their rotation around their axis.
The giant planets have many satellites: Jupiter has more than 60, Uranus has 27, Saturn has 62, Neptune has 13, as well as orbital rings, which, according to scientists, consist of the substance of collapsed satellites.
Behind the giant planets is a relatively small space object - Pluto. It was discovered in 1930 and has not yet been well studied. Until 2006, our solar system was thought to contain nine planets, and Pluto was the last of them. Currently he is ranked among