> Solar system
solar system– planets in order, Sun, structure, system model, satellites, space missions, asteroids, comets, dwarf planets, Interesting Facts.
solar system- a place in outer space in which the Sun, the planets in order, and many other space objects and celestial bodies are located. The solar system is the most precious place in which we live, our home.
Our Universe is a huge place where we occupy a tiny corner. But for earthlings, the Solar System seems to be the most vast territory, the farthest corners of which we are only beginning to approach. And it still hides a lot of mysterious and mysterious formations. So, despite centuries of study, we have only opened the door to the unknown. So what is the solar system? Today we will look at this issue.
Discovering the Solar System
In fact, you need to look into the sky and you will see our system. But few peoples and cultures understood exactly where we exist and what place we occupy in space. For a long time we thought that our planet was static, located in the center, and other objects rotated around it.
But still, even in ancient times, supporters of heliocentrism appeared, whose ideas would inspire Nicolaus Copernicus to create a true model where the Sun was located in the center.
In the 17th century, Galileo, Kepler and Newton were able to prove that planet Earth revolves around the star Sun. The discovery of gravity helped to understand that other planets follow the same laws of physics.
The revolutionary moment came with the advent of the first telescope from Galileo Galilei. In 1610, he noticed Jupiter and its moons. This will be followed by the discovery of other planets.
In the 19th century, three important observations were made that helped to calculate the true nature of the system and its position in space. In 1839, Friedrich Bessel successfully identified an apparent shift in stellar position. This showed that there is a huge distance between the Sun and the stars.
In 1859, G. Kirchhoff and R. Bunsen used the telescope to conduct a spectral analysis of the Sun. It turned out that it consists of the same elements as the Earth. The parallax effect can be seen in the bottom picture.
As a result, Angelo Secchi was able to compare the spectral signature of the Sun with the spectra of other stars. It turned out that they practically converge. Percival Lowell carefully studied the distant corners and orbital paths of the planets. He guessed that there was still an undisclosed object - Planet X. In 1930, Clyde Tombaugh noticed Pluto at his observatory.
In 1992, scientists expanded the boundaries of the system by discovering a trans-Neptunian object, 1992 QB1. From this moment on, interest in the Kuiper belt begins. This is followed by the findings of Eris and other objects from Michael Brown's team. All this will lead to a meeting of the IAU and the displacement of Pluto from the status of a planet. Below you can study in detail the composition of the Solar system, considering all the solar planets in order, the main star the Sun, the asteroid belt between Mars and Jupiter, the Kuiper belt and the Oort Cloud. The solar system also hides the most big planet(Jupiter) and the smallest (Mercury).
Structure and composition of the solar system
Comets are clumps of snow and dirt filled with frozen gas, rocks and dust. The closer they get to the Sun, the more they heat up and emit dust and gas, increasing their brightness.
Dwarf planets orbit the star, but have been unable to remove foreign objects from orbit. They are smaller in size than standard planets. The most famous representative is Pluto.
The Kuiper Belt lies beyond the orbit of Neptune, filled with icy bodies and formed as a disk. The most famous representatives are Pluto and Eris. Hundreds of ice dwarfs live on its territory. The farthest away is the Oort Cloud. Together they act as a source of arriving comets.
The solar system is only a small part of the Milky Way. Beyond its border there is a large-scale space filled with stars. At the speed of light it would take 100,000 years to cover the entire area. Our galaxy is one of many in the Universe.
In the center of the system is the main and only star - the Sun (main sequence G2). The first are the 4 terrestrial planets (inner), the asteroid belt, 4 gas giants, the Kuiper belt (30-50 AU) and the spherical Oort Cloud, extending to 100,000 AU. to the interstellar medium.
The Sun contains 99.86% of the entire system mass, and gravity is superior to all forces. Most of the planets are located near the ecliptic and rotate in the same direction (counterclockwise).
Approximately 99% of the planetary mass is represented by gas giants, with Jupiter and Saturn covering more than 90%.
Unofficially, the system is divided into several sections. The inner one includes 4 terrestrial planets and an asteroid belt. Next comes the outer system with 4 giants. A zone with trans-Neptunian objects (TNOs) is separately identified. That is, you can easily find the outer line, since it is marked by the large planets of the solar system.
Many planets are considered mini-systems because they have a group of satellites. Gas giants also have rings - small bands of small particles revolving around the planet. Typically large moons arrive in a gravitational block. On the lower layout you can see a comparison of the sizes of the Sun and the planets of the system.
The sun is 98% hydrogen and helium. Terrestrial planets are endowed with silicate rock, nickel and iron. The giants consist of gases and ices (water, ammonia, hydrogen sulfide and carbon dioxide).
Bodies in the Solar System that are distant from the star have low temperatures. From here, the ice giants (Neptune and Uranus) are distinguished, as well as small objects beyond their orbits. Their gases and ices are volatile substances that can condense at a distance of 5 AU. from the sun.
Origin and evolutionary process of the Solar System
Our system appeared 4.568 billion years ago as a result of the gravitational collapse of a large molecular cloud represented by hydrogen, helium and a small amount of heavier elements. This mass collapsed, resulting in rapid rotation.
Most of the mass gathered in the center. The temperature was rising. The nebula was shrinking, increasing the acceleration. This resulted in flattening into a protoplanetary disk containing a hot protostar.
Because of high level boiling near a star, only metals and silicates can exist in solid form. As a result, 4 terrestrial planets appeared: Mercury, Venus, Earth and Mars. Metals were scarce, so they were unable to increase their size.
But the giants appeared further out, where the material was cool and allowed the volatile ice compounds to remain solid. There was much more ice, so the planets dramatically increased in size, attracting huge amounts of hydrogen and helium into the atmosphere. The remnants failed to become planets and settled in the Kuiper belt or retreated to the Oort Cloud.
Over 50 million years of development, the pressure and density of hydrogen in the protostar triggered nuclear fusion. Thus the Sun was born. The wind created the heliosphere and scattered gas and dust into space.
The system remains in its usual state for now. But the Sun develops and after 5 billion years completely transforms hydrogen into helium. The core will collapse, releasing a huge energy reserve. The star will increase in size by 260 times and become a red giant.
This will lead to the death of Mercury and Venus. Our planet will lose life because it will become hot. Eventually, the outer layers of stars will burst into space, leaving behind a white dwarf the size of our planet. A planetary nebula will form.
Inner Solar System
This is a line with the first 4 planets from the star. They all have similar parameters. This is a rocky type, represented by silicates and metals. Closer than the giants. They are inferior in density and size, and also lack huge lunar families and rings.
Silicates form the crust and mantle, and metals are part of the cores. All except Mercury have an atmospheric layer that allows them to shape weather conditions. Impact craters and tectonic activity are visible on the surface.
Closest to the star is Mercury. It is also the tiniest planet. The magnetic field reaches only 1% of Earth's, and the thin atmosphere causes the planet to be half-hot (430°C) and freezing (-187°C).
Venus similar in size to the Earth and has a dense atmospheric layer. But the atmosphere is extremely toxic and acts as a greenhouse. 96% consists of carbon dioxide, along with nitrogen and other impurities. Dense clouds are made from sulfuric acid. There are many canyons on the surface, the deepest of which reaches 6,400 km.
Earth best studied because this is our home. It has a rocky surface covered with mountains and depressions. In the center is a heavy metal core. There is water vapor in the atmosphere, which smoothes temperature regime. The Moon rotates nearby.
Because of appearance Mars received the nickname Red Planet. The color is created by the oxidation of iron materials on the top layer. It is endowed with the largest mountain in the system (Olympus), rising to 21229 m, as well as the deepest canyon - Valles Marineris (4000 km). Much of the surface is ancient. There are ice caps at the poles. A thin atmospheric layer hints at water deposits. The core is solid, and next to the planet there are two satellites: Phobos and Deimos.
Outer Solar System
Gas giants are located here - large planets with lunar families and rings. Despite their size, only Jupiter and Saturn can be seen without the use of telescopes.
The largest planet in the solar system is Jupiter with a rapid rotational speed (10 hours) and an orbital path of 12 years. The dense atmospheric layer is filled with hydrogen and helium. The core can reach the size of the Earth. There are many moons, faint rings and the Great Red Spot - a powerful storm that has not calmed down since the 4th century.
Saturn- a planet that is recognized by its gorgeous ring system (7 pieces). The system contains satellites, and the hydrogen and helium atmosphere rotates rapidly (10.7 hours). It takes 29 years to go around the star.
In 1781, William Herschel found Uranus. A day on the giant lasts 17 hours, and the orbital path takes 84 years. Holds huge amounts of water, methane, ammonia, helium and hydrogen. All this is concentrated around the stone core. There is a lunar family and rings. Voyager 2 flew to it in 1986.
Neptune– a distant planet with water, methane, ammonium, hydrogen and helium. There are 6 rings and dozens of satellites. Voyager 2 also flew by in 1989.
Trans-Neptunian region of the Solar System
Thousands of objects have already been found in the Kuiper belt, but it is believed that up to 100,000 with a diameter of more than 100 km live there. They are extremely small and located at large distances, so it is difficult to calculate the composition.
The spectrographs show an icy mixture of hydrocarbons, water ice and ammonia. Initial analysis showed a wide color range: from neutral to bright red. This hints at the richness of the composition. A comparison of Pluto and KBO 1993 SC showed that they are extremely different in surface elements.
Water ice was found in 1996 TO66, 38628 Huya and 20000 Varuna, and crystalline ice was noticed in Quavar.
Oort cloud and beyond the solar system
This cloud is believed to extend to 2000-5000 AU. and up to 50,000 a.u. from the star. The outer edge can extend to 100,000-200,000 au. The cloud is divided into two parts: spherical outer (20000-50000 AU) and internal (2000-20000 AU).
The outer one is home to trillions of bodies with a diameter of a kilometer or more, as well as billions with a width of 20 km. There is no exact information about the mass, but it is believed that Halley's comet is a typical representative. The total mass of the cloud is 3 x 10 25 km (5 lands).
If we focus on comets, most of the cloud bodies are composed of ethane, water, carbon monoxide, methane, ammonia and hydrogen cyanide. The population is 1-2% made up of asteroids.
Bodies from the Kuiper Belt and Oort Cloud are called trans-Neptunian objects (TNOs) because they are located further than Neptune's orbital path.
Exploring the Solar System
The size of the solar system still seems immense, but our knowledge has expanded significantly with the sending of probes into outer space. The boom in space exploration began in the mid-20th century. Now it can be noted that to all solar planets At least once, earthly spacecraft approached. We have photos, videos, as well as soil and atmosphere analysis (for some).
The first artificial spacecraft was the Soviet Sputnik 1. He was sent into space in 1957. Spent several months in orbit collecting data on the atmosphere and ionosphere. In 1959, the United States joined with Explorer 6, which took pictures of our planet for the first time.
These devices provided a huge amount of information about planetary features. Luna-1 was the first to go to another object. It flew past our satellite in 1959. Mariner was a successful mission to Venus in 1964, Mariner 4 arrived at Mars in 1965, and the 10th mission passed Mercury in 1974.
Since the 1970s The attack on the outer planets begins. In 1973, Pioneer 10 flew past Jupiter, and the next mission visited Saturn in 1979. A real breakthrough was the Voyagers, which flew around large giants and their satellites in the 1980s.
The Kuiper Belt is being explored by New Horizons. In 2015, the device successfully reached Pluto, sending the first close images and a lot of information. Now he is rushing to distant TNOs.
But we longed to land on another planet, so rovers and probes began to be sent in the 1960s. Luna 10 was the first to enter lunar orbit in 1966. In 1971, Mariner 9 settled near Mars, and Verena 9 orbited the second planet in 1975.
Galileo first orbited near Jupiter in 1995, and the famous Cassini appeared near Saturn in 2004. MESSENGER and Dawn visited Mercury and Vesta in 2011. And the last one still managed to fly around dwarf planet Ceres in 2015.
The first spacecraft to land on the surface was Luna 2 in 1959. This was followed by landings on Venus (1966), Mars (1971), asteroid 433 Eros (2001), Titan and Tempel in 2005.
Currently, manned vehicles have only visited Mars and the Moon. But the first robotic one was Lunokhod-1 in 1970. Spirit (2004), Opportunity (2004) and Curiosity (2012) landed on Mars.
The 20th century was marked by the space race between America and the USSR. For the Soviets it was the Vostok program. The first mission came in 1961, when Yuri Gagarin found himself in orbit. In 1963, the first woman flew, Valentina Tereshkova.
In the USA they developed the Mercury project, where they also planned to launch people into space. The first American to go into orbit was Alan Shepard in 1961. After both programs ended, countries focused on long-term and short-term flights.
The main goal was to land a man on the moon. The USSR was developing a capsule for 2-3 people, and Gemini was trying to create a device for a safe lunar landing. It ended with the fact that in 1969, Apollo 11 successfully landed Neil Armstrong and Buzz Aldrin on the satellite. In 1972, 5 more landings were carried out, and all were Americans.
The next challenge was to create space station and reusable devices. The Soviets formed the Salyut and Almaz stations. The first station with a large number crews became NASA's Skylab. The first settlement was the Soviet Mir, operating in 1989-1999. In 2001 it was replaced by the International Space Station.
The only reusable spacecraft was Columbia, which completed several orbital flights. The 5 shuttles completed 121 missions before retiring in 2011. Due to accidents, two shuttles crashed: Challenger (1986) and Columbia (2003).
In 2004, George W. Bush announced his intention to return to the Moon and conquer the Red Planet. This idea was also supported by Barack Obama. As a result, all efforts are now spent on exploring Mars and plans to create a human colony.
All these flights and sacrifices have led to a better understanding of our system, its past and future. The modern model contains 8 planets, 4 dwarfs and a huge number of TNOs. Let's not forget about the army of asteroids and planetesimals.
On the page you can find out not only useful information about the solar system, its structure and dimensions, but also get detailed description and characteristics of all planets in order with names, photos, videos, diagrams and distance from the Sun. The composition and structure of the solar system will no longer be a mystery. Also use our 3D model to explore all the celestial bodies yourself.
This is a system of planets, at the center of which is bright Star, 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 new star The sun and our entire solar system.
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...
Quick answer: 8 planets.
The solar system is a planetary system that includes the central star, which is the Sun, as well as all other natural space objects, which in turn revolve around the Sun.
Interestingly, most of the total mass of the solar system is accounted for by itself, while the rest is accounted for by 8 planets. Yes, yes, there are 8 planets in the solar system, and not 9, as some people believe. Why do they think so? One reason is that they mistake the Sun for another planet, but in fact it is the only star included in the solar system. But in reality everything is simpler - Pluto was previously considered a planet, but is now considered a dwarf planet.
Let's begin the review of the planets, starting with the one closest to the Sun.
Mercury
This planet was named after the ancient Roman god of trade - the fleet-footed Mercury. The fact is that it moves much faster than other planets.
Mercury completely revolves around the Sun in 88 Earth days, while the duration of one sidereal day on Mercury is 58.65 Earth days.
Relatively little is known about the planet, and one of the reasons is that Mercury is too close to the Sun.
Venus
Venus is the second so-called inner planet of the solar system, which was named after the goddess of love, Venus. It is worth noting that this is the only planet that received its name in honor of a female deity, rather than a male one.
Venus is very similar to Earth, not only in size, but also in composition and even gravity.
It is believed that Venus once had many oceans similar to the ones we have. However, some time ago the planet heated up so much that all the water evaporated, leaving behind only rocks. Water vapor was carried into outer space.
Earth
The third planet is Earth. It is the largest planet among the terrestrial planets.
It was formed approximately 4.5 billion years ago, after which it was almost immediately joined by its only satellite, which is the Moon. It is believed that life on Earth appeared about 3.9 billion years ago and over time its biosphere began to change into better side, which made it possible to form ozone layer, increase the growth of aerobic organisms, etc. All this, among other things, allows us to exist now.
Mars
Mars closes the four terrestrial planets. The planet is named after the ancient Roman god of war, Mars. This planet is also called red because its surface has a reddish tint due to iron oxide.
Mars has surface pressure 160 times less than Earth's. On the surface there are craters similar to those that can be seen on the Moon. There are also volcanoes, deserts, valleys and even ice caps.
Mars has two satellites: Deimos and Phobos.
Jupiter
It is the fifth planet from the Sun and the first among the giant planets. By the way, it is the largest in the solar system, which received its name in honor of the ancient Roman supreme god of thunder.
Jupiter has been known for a long time, which is reflected in ancient myths and legends. Has very a large number of satellites - 67 to be exact. Interestingly, some of them were discovered several centuries ago. Thus, Galileo Galilei himself discovered 4 satellites in 1610.
Sometimes Jupiter can be seen with the naked eye, as was the case in 2010.
Saturn
Saturn is the second largest planet in the solar system. It was named after the Roman god of agriculture.
It is known that Saturn consists of hydrogen with signs of water, helium, ammonia, methane and other heavy elements. An unusual wind speed was observed on the planet - about 1800 kilometers per hour.
Saturn has prominent rings that are mostly made of ice, dust, and other elements. Saturn also has 63 satellites, one of which, Titan, is larger than even Mercury.
Uranus
The seventh planet in terms of distance from the Sun. It was discovered relatively recently (in 1781) by William Herschel and was named after the god of the sky.
Uranus is the first planet to be discovered using a telescope, between the Middle Ages and modern times. Interestingly, although the planet can sometimes be seen with the naked eye, before its discovery it was generally believed that it was a dim star.
Uranus has a lot of ice but no metallic hydrogen. The planet's atmosphere is composed of helium and hydrogen, as well as methane.
Uranus has a complex ring system and 27 satellites.
Neptune
Finally, we have reached the eighth and last planet of the solar system. The planet is named after the Roman god of the seas.
Neptune was discovered in 1846, and, interestingly, not through observations, but thanks to mathematical calculations. Initially, only one of its satellites was discovered, although the remaining 13 were not known until the 20th century.
Neptune's atmosphere consists of hydrogen, helium and possibly nitrogen. The most raging here strong winds, the speed of which reaches a fantastic 2100 km/h. In the upper layers of the atmosphere the temperature is about 220°C.
Neptune has a poorly developed ring system.
a > > Dimensions of the planets of the solar system
Sizes of the planets of the solar system in order. Description with photos for all the planets around the Sun, comparison with the Earth and rating: from smallest to largest.
If you like planets, then you can learn a lot only within our system. Solar facilities provide different kinds and each specimen is endowed with its own unique characteristics. But the size is also striking. To find out the details, it's worth starting with the history of the formation of the solar system.
The Birth of the Solar System
The solar system appeared 4.5 billion years ago. This figure comes from analysis of terrestrial rocks and space rocks, as well as computer models. Researchers believe it all started with a rotating haze of dust and gas. One day, gravity caused it to collapse and our star appeared. Theories say that its energy repelled lighter elements and attracted larger ones.
Over millions of years, the particles merged and rotated, creating larger objects. This is how the planets appeared. Most of the gas escaped into external system, giving birth to gas giants, and terrestrial-type planets remained in the inner one.
Until the 1990s. scientists had modest knowledge about the planets. But technology developed and it turned out that there are also many planets outside our system. Some of them were even larger than Jupiter, while others resembled our Earth.
There were also objects like Pluto in the solar system. This forced the IAU to introduce new criteria and the 9th planet was shifted to the dwarf category.
Nowadays, a planet is considered a body that makes an orbital passage around the Sun with sufficient massiveness to achieve hydrostatic balance and clear the orbit of foreign objects.
Dimensions of the 8 planets of the solar system in numbers
Let's look at the sizes of the planets of the Solar System in descending order of radius (from largest to smallest):
- Jupiter (69,911 km) – 1.120% of Earth's.
- Saturn (58,232 km) - 945% of Earth's.
- Uranus (25,362 km) – 400% of Earth’s.
- Neptune (24,622 km) – 388% of Earth.
- Earth (6,371 km).
- Venus (6,052 km) – 95% of Earth’s.
- Mars (3390 km) – 53% of Earth’s.
- Mercury (2440 km) – 38% of Earth’s.
Jupiter is the largest planet in the solar system. Its gravity influenced the movement of the inner planets and the distribution of mass during formation. It can also attract and repel comets and asteroids from Earth.
Saturn is notable for its ring system. And Uranus and Neptune are representatives of the ice giants.
The inner planets of the terrestrial group include: Venus (earthly sister), Mars (cool desert), Mercury (the smallest) and Earth - home.
solar system is a system of celestial bodies welded together by forces of mutual attraction. It includes: the central star - the Sun, 8 large planets with their satellites, several thousand small planets, or asteroids, several hundred observed comets and countless meteoroids, dust, gas and small particles .
It was formed by gravitational compression gas and dust cloud approximately 4.57 billion years ago.
Sun
The Sun is the closest star to Earth; all the others are immeasurably further away from us. For example, the closest star to us is Proxima from the system a Centauri is 2500 times farther than the Sun. For the Earth, the Sun is a powerful source of cosmic energy. It provides the light and heat necessary for flora and fauna, and forms the most important properties of the Earth's atmosphere.. In general, the Sun determines the ecology of the planet. Without it, there would be no air necessary for life: it would turn into a liquid nitrogen ocean around frozen waters and icy land. For us earthlings, most important feature The sun is that our planet arose near it and life appeared on it.
Merkur th
Mercury is the planet closest to the Sun.
The ancient Romans considered Mercury the patron of trade, travelers and thieves, as well as the messenger of the gods. It is not surprising that a small planet, quickly moving across the sky following the Sun, received his name. Mercury has been known since ancient times, but ancient astronomers did not immediately realize that they saw the same star in the morning and evening. Mercury is closer to the Sun than the Earth: the average distance from the Sun is 0.387 AU, and the distance to Earth ranges from 82 to 217 million km. The inclination of the orbit to the ecliptic i = 7° is one of the largest in the Solar System. Mercury's axis is almost perpendicular to the plane of its orbit, and the orbit itself is very elongated (eccentricity e = 0.206). The average speed of Mercury's orbit is 47.9 km/s. Due to the tidal influence of the Sun, Mercury fell into a resonant trap. The period of its revolution around the Sun (87.95 Earth days), measured in 1965, relates to the period of rotation around its axis (58.65 Earth days) as 3/2. Mercury completes three full revolutions around its axis in 176 days. During the same period, the planet makes two revolutions around the Sun. Thus, Mercury occupies the same position in orbit relative to the Sun, and the orientation of the planet remains the same. Mercury has no satellites. If they were, then during the formation of the planets they fell on protomercury. The mass of Mercury is almost 20 times less than the mass of the Earth (0.055M or 3.3 10 23 kg), and its density is almost the same as that of the Earth (5.43 g/cm3). The radius of the planet is 0.38R (2440 km). Mercury is smaller than some of the moons of Jupiter and Saturn.
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. Thanks to greenhouse effect, the surface temperature heats up to hundreds of degrees. The atmosphere, which is a thick blanket of carbon dioxide, traps heat coming from the Sun. This results in the temperature of the atmosphere being 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 pressure at the surface 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. For a few weeks every seven months, Venus is the brightest object in the western sky in the evenings. Three and a half months later, it rises three hours earlier than the Sun, becoming the sparkling “morning star” of the eastern sky. Venus can be observed an hour after sunset or an hour before sunrise. Venus has no satellites.
Third from Sol 
ntsa planet. The speed of the Earth's revolution in an elliptical orbit around the Sun is 29.765 km/s. The inclination of the earth's axis to the ecliptic plane is 66 o 33 "22". The Earth has a natural satellite - the Moon. The Earth has a magnetic fieldital and electric fields. The Earth was formed 4.7 billion years ago from gas dispersed in the protosolar system-dust substances. 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 PThe surface is occupied by the World Ocean (361.1 million km 2; 70.8%); the land area is 149.1 million km 2 and forms six motherscoves and islands. It rises above sea level by an average of 875 meters ( highest height 8848 meters - Chomolungma city). Mountains occupy 30% of the land, deserts cover about 20% of the land surface, savannas and woodlands - about 20%, forests - about 30%, glaciers - 10%. The average depth of the ocean is about 3800 meters, the greatest is 11022 meters (Mariana Trench in the Pacific Ocean), the volume of water is 1370 million km 3, the average salinity is 35 g/l. The Earth's atmosphere, 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
The fourth planet from the Sun, similar to Earth, but smaller and cooler. Mars has deep canyons
giant volcanoes and vast deserts. There are two small moons flying around the Red Planet, as Mars is also called: Phobos and Deimos. Mars is the next planet after the Earth, if you count from the Sun, and the only cosmic world besides the Moon that can already be reached with the help of modern rockets. For astronauts, this four-year journey could represent the next frontier in space exploration. Near the equator of Mars, in an area called Tharsis, there are volcanoes of colossal size. Tarsis is the name that astronomers gave to the hill, which has 400 km. wide and about 10 km. in height. There are four volcanoes on this plateau, each of which is simply gigantic compared to any terrestrial volcano. The largest volcano on Tharsis, Mount Olympus, rises 27 km above the surrounding area. About two-thirds of the surface of Mars is mountainous area with a large number of impact craters surrounded by hard rock debris. Near the volcanoes of Tharsis, a vast system of canyons snakes around the length of about a quarter of the equator. The Valles Marineris 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 valley floor to the plateau above. In ancient times, there was a lot of water on Mars; large rivers flowed across the surface of this planet. There are ice caps at the South and North Poles of Mars. But this ice does not consist of water, but of frozen atmospheric carbon dioxide (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 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 at the surface is 5-7 hPa. In total, about 30 interplanetary space stations were sent to Mars.
Jupiter
The fifth planet from the Sun, the largest planet in the Solar System. Jupiter is not a rocky planet. Unlike the four rocky planets closest to the Sun, Jupiter is a gas ball. Atmospheric composition: H 2 (85%), CH 4, NH 3, He (14%). Jupiter's gas composition is very similar to the sun's. Jupiter is a powerful source of thermal radio emission. Jupiter has 16 satellites (Adrastea, Metis, Amalthea, Thebe, Io, Lysithea, Elara, Ananke, Karme, Pasiphae, 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 high that the planet bulges along the equator. In addition, this rapid rotation causes very strong winds in the upper atmosphere, where clouds stretch out into 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 turns from a gas into a liquid, and then from a liquid into a solid. At a depth of 100 km. there is a boundless ocean of liquid hydrogen. Below 17,000 km. hydrogen is compressed so tightly that its atoms are destroyed. And then it begins to behave like metal; in this state it easily conducts electricity. The electric current flowing in metallic hydrogen creates a strong magnetic field around Jupiter.
Saturn
The sixth planet from the Sun has an amazing ring system. Due to its rapid rotation around its axis, Saturn seems to be flattened at the poles. Wind speeds at the equator reach 1800 km/h. The width of Saturn's rings is 400,000 km, but they are only a few tens of meters thick. The inner parts of the rings rotate around Saturn faster than the outer ones. The rings are primarily made up of billions of small particles, each orbiting Saturn as its own microscopic satellite. These "micro-satellites" are likely made of water ice or rocks covered in 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
Seventh from 
Sun planet. It was discovered in 1781 by the English astronomer William Herschel, and named after Greek about the sky god Uranus. The orientation of Uranus in space differs from the other 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 faces the Sun alternately with the north pole, the south, the equator, and the middle latitudes. Uranus has more than 27 satellites (Miranda, Ariel, Umbriel, Titania, Oberon, Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Peck, etc.) and a system of rings. At the center of Uranus is a core made of rock and iron. The composition of the atmosphere includes: H 2, He, CH 4 (14%).
Neptune
E Its orbit intersects with Pluto's orbit in some places. The equatorial diameter is the same as that of Uranus, although ra 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 cognition of nature was the discovery of the planet Neptune through calculations - “at the tip of a pen.” Uranus, the planet next to Saturn, which for many centuries was considered the most distant planet, was discovered by W. 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 barely noticeably from the path it should follow, taking into account the disturbances from all the known planets. Thus, the theory of the movement of celestial bodies, so strict and accurate, was put to the test. Le Verrier (in France) and Adams (in England) suggested that if disturbances from the known planets do not explain the deviation in the movement 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 producing these deviations with its gravity. They calculated the orbit of the unknown planet, its mass and indicated the place in the sky where the unknown planet should have been located at that time. This planet was found through a telescope at the place they indicated in 1846. It was named Neptune. Neptune is not visible to the naked eye. On this planet, winds blow at speeds of 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. Has 6 satellites (one of them is Triton).
Neptune is the god of the seas in Roman mythology.
