This is a system of planets, in the center of which is a bright star, the 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 arose new star The sun and our entire solar system.
To the center solar system There is the Sun, around which nine large planets revolve in orbits. Since the Sun is displaced from the center of the planetary orbits, then during the cycle of revolution around the Sun, the planets either approach or move away in their orbits.
There are two groups of planets:
planets terrestrial group: and . These planets are small in size with a rocky surface, they are closer than others to the Sun.
Giant planets: and . These are large planets, consisting mainly of gas, and they are characterized by the presence of rings consisting of ice dust and many rocky pieces.
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 start 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, unlike other features ...
Rings and moons of Saturn: Titan, Enceladus and more...
Not only the planet Saturn has characteristic rings, but also on 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 of the solar system ...
Rings and moons of Uranus: Titania, Oberon and others...
The planet Uranus has 17 satellites and, like other giant planets, thin rings encircling the planet, which practically do not have the ability to reflect light, therefore they were discovered not so long ago in 1977 quite by accident ...
Rings and moons of Neptune: 
Triton, Nereid and others...
Initially, before the exploration of Neptune by the Voyager 2 spacecraft, it was known about two satellites of the planet - Triton and Nerida. Interesting fact 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 mass (from liquid to vapor) for many kilometers into the atmosphere. During its mission, Voyager 2 discovered six more satellites of the planet Neptune...
The 10th planet of the solar system, judging by some data from celestial mechanics, simply had to exist. For a long time it was only a theoretical argument, practically not confirmed by anything. However, in last years scientists were actually able to detect and describe this data in more or less detail, as far as possible. In general, officially there are still 9 planets in our system. Nevertheless, in the near future, it is quite possible that a new body will also appear in the entire educational literature. Naturally, provided that scientists can agree and come to a common opinion on this issue.
Structure of the solar system
For many years it was believed that we have only 9 planets in the system. Basically, this opinion arose only because the available tracking facilities were not enough to study the farthest outskirts. Nevertheless, technology is constantly developing, and humanity is beginning to receive more and more new data, among which information has appeared that the 10th planet of the solar system actually exists. Despite the availability of confirmed data, disputes do not subside to this day. Some scientists do not agree that this cosmic body is really a planet. It is too small, and with a certain tension of fantasy, it is quite capable of being simply too small. big asteroid. In any case, no one refuses the fact that something like this really exists. The only question that remains open is what exactly the name of the 10th planet of the solar system will be. But on the condition that it really will be assigned to this category, and will not be considered a kind of planetoid or something else, different from the more familiar to most people.
UB313, or 10th planet in the solar system
Naturally, it cannot remain nameless by definition. In practice, all newly discovered objects of this type are given designations of numbers and letters, which allow you to better navigate and not explain for a very long time what exactly in question. Officially, the tenth planet of the solar system is called UB313, but it also has an unofficial nickname - Xena. It should be noted that there are several such names for an open cosmic body, and so far none has finally settled down. Most often, a designation consisting of numbers and letters is used.
Detection
In fact, the first data appeared back in 2003, when the rest of the planets of the solar system were being studied. 10 the planet was not initially considered in this form. Then they thought it was some strange object with an incomprehensible trajectory, dimensions, and so on. To clarify the data, further study was required, but this also became impossible, because immediately after the discovery, the planet disappeared from sight for a very long time. In 2005, new data came - it was then that it turned out to find this object again. About the name of the 10th planet of the solar system, then no one thought. Despite all the information available, they could only say something for sure about this celestial body quite recently, when no one had any doubts about the existence of this object. The planet was discovered with the help of a telescope located in Hawaii, the equipment of Samuel Oschin, with the help of Professor David Rabinovich, Michael Brown and Chad Trujillo. All these people helped in one way or another in the search and deserve to have their names recorded in history. Many astronomers, both amateur and professional, note that this is the first major discovery since 1846, when Neptune was found.
Planet parameters
The 10th planet of the solar system is slightly larger than Pluto. Approximately 700 kilometers. The total diameter is approximately 3 thousand kilometers. The most interesting thing here is where exactly this object is located. Previously, it was believed that Pluto is the most distant celestial body from the star. But this planet, Xena, or UB313, is just twice as far away. That is, Pluto has lost its status as the most distant of the large objects. Judging by some reports, Xena is a rocky planet, which includes various rocks, as well as ice. There is a theory that this position of a space object is due to the gravitational influence of Neptune. AT recent times there was another very interesting information. It turns out that the 10th planet of the solar system is very similar in structure and surface features to Pluto. This provides food for numerous theories about how exactly this celestial body was formed.
Travel speed
One of the main problems on which information about this object has been collected for so long is its speed. It is known that all the planets of the solar system are moving. The 10th planet is no exception in this regard. But the speed of its movement in space is so insignificant that for a very long time no one could accurately predict and calculate exactly where it would be in the next moment. As soon as they were able to deal with this issue, new data immediately began to appear. In general, no one knows the exact trajectory of the planet, but it's just a matter of time. To understand exactly how an object will move, you need to detect its position in the largest possible number of points. Until then, only theoretical calculations can be taken into account.
Features of the outskirts of our system
Now that questions about whether there is a 10th planet in the solar system can be considered closed, scientists have turned their eyes to the distant outskirts of space. It is believed that beyond the orbit of UB313 there are many more such bodies, the size of which can vary within a fairly wide range. It is known that on the outskirts of the system is located great amount asteroids. Among them, the most unusual and unexpected cosmic bodies may well be hiding. Unfortunately, until humanity develops to normally fly to distant frontiers or study them in detail remotely, nothing can be said for sure.
Nubiru theory
The existence of such an object has been known for a very long time. One of the theories says that this planet is called Nubiru, and not everything is so simple with it. Indirect links to various features and incomprehensible moments in the history of mankind clearly indicate the direct influence of the inhabitants of this celestial body on our planet. It is believed that the population of this object is much more developed than humanity. Naturally, they do not have a question about which is the 10th planet of the solar system. They live on it. Scientists are skeptical about the idea for so many reasons, but the theory still has a lot of fans, especially since there really is a lot of data that cannot be explained in any other way. Supporters point to the extremely disproportionate development of mankind, which took place as if by a sharp leap. Very similar to the changes genetic level. On the other hand, they also say that the trajectory of Nubiru is such that it approaches the Earth only once every 3600 years. Where the planet is the rest of the time is unclear. And if this is indeed true, then, in theory, the inhabitants of this mythical object live in incredible conditions that are radically different from ours.
Outcome
There are 10 planets in the solar system. This is a proven fact. Humanity still knows very little about it, but this is true for any other cosmic body. In any case, this is indeed a significant discovery over a very long time period, which opened a new page in astronomy. Now scientists will look much closer at the outskirts of our system, because no one excludes that there are a huge number of similar objects there, and some of them may be even more mysterious than anything that has already been discovered.
On March 13, 1781, English astronomer William Herschel discovered the seventh planet in the solar system - Uranus. And on March 13, 1930, American astronomer Clyde Tombaugh discovered the ninth planet in the solar system - Pluto. By the beginning of the 21st century, it was believed that the solar system included nine planets. However, in 2006, the International Astronomical Union decided to strip Pluto of this status.
There are already 60 known natural satellites of Saturn, most of which have been discovered using spacecraft. Most satellites are made up of rocks and ice. The largest satellite, Titan, discovered in 1655 by Christian Huygens, is larger than the planet Mercury. The diameter of Titan is about 5200 km. Titan orbits Saturn every 16 days. Titan is the only satellite to have a very dense atmosphere, 1.5 times the size of Earth's, and consisting mostly of 90% nitrogen, with a moderate amount of methane.
The International Astronomical Union officially recognized Pluto as a planet in May 1930. At that moment, it was assumed that its mass was comparable to the mass of the Earth, but later it was found that the mass of Pluto is almost 500 times less than the Earth's, even less than the mass of the Moon. The mass of Pluto is 1.2 times 1022 kg (0.22 Earth masses). The average distance of Pluto from the Sun is 39.44 AU. (5.9 by 10 to the 12th degree km), the radius is about 1.65 thousand km. The period of revolution around the Sun is 248.6 years, the period of rotation around its axis is 6.4 days. The composition of Pluto supposedly includes rock and ice; the planet has a thin atmosphere composed of nitrogen, methane and carbon monoxide. Pluto has three moons: Charon, Hydra and Nyx.
At the end of XX and early XXI centuries, many objects have been discovered in the outer part of the solar system. It has become clear that Pluto is only one of the largest Kuiper belt objects known to date. Moreover, at least one of the objects of the belt - Eris - is a larger body than Pluto and 27% heavier than it. In this regard, the idea arose to no longer consider Pluto as a planet. On August 24, 2006, at the XXVI General Assembly of the International Astronomical Union (IAU), it was decided to henceforth call Pluto not a "planet", but " dwarf planet".
At the conference, a new definition of the planet was developed, according to which planets are considered to be bodies revolving around a star (and not being a star themselves), having a hydrostatic equilibrium shape and "clearing" the area in the region of their orbit from other, smaller, objects. Dwarf planets will be considered objects that revolve around a star, have a hydrostatically equilibrium shape, but have not "cleared" the nearby space and are not satellites. Planets and dwarf planets are two different classes of solar system objects. All other objects revolving around the Sun and not being satellites will be called small bodies of the solar system.
Thus, since 2006, there have been eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Five dwarf planets are officially recognized by the International Astronomical Union: Ceres, Pluto, Haumea, Makemake, and Eris.
On June 11, 2008, the IAU announced the introduction of the concept of "plutoid". It was decided to call plutoids celestial bodies revolving around the Sun in an orbit whose radius is greater than the radius of Neptune's orbit, the mass of which is sufficient to gravitational forces gave them an almost spherical shape, and which do not clear the space around their orbit (that is, many small objects circle around them).
Since it is still difficult to determine the shape and thus the relation to the class of dwarf planets for such distant objects as plutoids, scientists recommended temporarily assigning to plutoids all objects whose absolute asteroid magnitude (brilliance from a distance of one astronomical unit) is brighter than +1. If it later turns out that the object assigned to the plutoids is not a dwarf planet, it will be deprived of this status, although the assigned name will be left. The dwarf planets Pluto and Eris were classified as plutoids. In July 2008, Makemake was included in this category. On September 17, 2008, Haumea was added to the list.
The material was prepared on the basis of information from open sources
solar system- these are 8 planets and more than 63 of their satellites, which are being discovered more often, several dozen comets and a large number of asteroids. All cosmic bodies move along their clear directed trajectories around the Sun, which is 1000 times heavier than all the bodies in the solar system combined. The center of the solar system is the Sun - a star around which planets revolve in orbits. They do not emit heat and do not glow, but only reflect the light of the sun. There are currently 8 officially recognized planets in the solar system. Briefly, in order of distance from the sun, we list them all. And now some definitions.
Planet- this is a celestial body that must satisfy four conditions:
1. the body must revolve around a star (for example, around the Sun);
2. the body must have sufficient gravity to have a spherical or close to it shape;
3. the body should not have other large bodies near its orbit;
4. the body should not be a star
Planet satellites. The solar system also includes the Moon and the natural satellites of other planets, which all of them have, except for Mercury and Venus. More than 60 satellites are known. Most satellites outer planets discovered when they received photographs taken by robotic spacecraft. Jupiter's smallest moon, Leda, is only 10 km across.
is a star, without which life on Earth could not exist. It gives us energy and warmth. According to the classification of stars, the Sun is a yellow dwarf. The age is about 5 billion years. It has a diameter at the equator equal to 1,392,000 km, 109 times larger than the earth. The rotation period at the equator is 25.4 days and 34 days at the poles. The mass of the Sun is 2x10 to the 27th power of tons, approximately 332950 times the mass of the Earth. The temperature inside the core is about 15 million degrees Celsius. The surface temperature is about 5500 degrees Celsius. By chemical composition The sun is made up of 75% hydrogen, and the other 25% of the elements has the most helium. Now let's figure out in order how many planets revolve around the sun, in the solar system and the characteristics of the planets.
Four inner planets(nearest to the Sun) - Mercury, Venus, Earth and Mars - have a solid surface. They are smaller than four giant planets. Mercury moves faster than other planets, being burned by the sun's rays during the day and freezing at night.
Period of revolution around the Sun: 87.97 days. Diameter at the equator: 4878 km.
Rotation period (turn around the axis): 58 days.
Surface temperature: 350 during the day and -170 at night.
Atmosphere: very rarefied, helium.
How many satellites: 0.
The main satellites of the planet: 0.
More like the Earth in size and brightness. Observation of it is difficult because of the clouds enveloping it. The surface is a hot rocky desert. 
Period of revolution around the Sun: 224.7 days.
Diameter at the equator: 12104 km.
Rotation period (turn around the axis): 243 days.
Surface temperature: 480 degrees (average).
Atmosphere: dense, mostly carbon dioxide.
How many satellites: 0.
The main satellites of the planet: 0.
Apparently, the Earth was formed from a gas and dust cloud, like other planets. Particles of gas and dust, colliding, gradually "raised" the planet. The temperature on the surface reached 5000 degrees Celsius. Then the Earth cooled down and became covered with a hard stone crust. But the temperature in the depths is still quite high - 4500 degrees. Rocks in the bowels are molten and pour out to the surface during volcanic eruptions. Only on earth there is water. That's why life exists here. It is located relatively close to the Sun to receive the necessary heat and light, but far enough away so as not to burn out.
Period of revolution around the Sun: 365.3 days. Diameter at the equator: 12756 km.
The period of rotation of the planet (rotation around the axis): 23 hours 56 minutes.
Surface temperature: 22 degrees (average).
Atmosphere: mostly nitrogen and oxygen.
Number of satellites: 1.
The main satellites of the planet: the Moon.
Due to the similarity with the Earth, it was believed that life exists here. But descended on the surface of Mars spacecraft found no signs of life. This is the fourth planet in order. 
Period of revolution around the Sun: 687 days.
Diameter of the planet at the equator: 6794 km.
Rotation period (rotation around the axis): 24 hours 37 minutes.
Surface temperature: -23 degrees (average).
Atmosphere of the planet: rarefied, mostly carbon dioxide.
How many satellites: 2.
Main moons in order: Phobos, Deimos.
Jupiter, Saturn, Uranus and Neptune are made up of hydrogen and other gases. Jupiter is more than 10 times larger than Earth in diameter, 300 times in mass and 1300 times in volume. It is more than twice as massive as all the planets in the solar system combined. How much planet Jupiter does it take to become a star? It is necessary to increase its mass by 75 times!
The period of revolution around the Sun: 11 years 314 days. Diameter of the planet at the equator: 143884 km.
Rotation period (turn around the axis): 9 hours 55 minutes.
Surface temperature of the planet: -150 degrees (average).
Number of satellites: 16 (+ rings).
The main satellites of the planets in order: Io, Europa, Ganymede, Callisto.
This is the number 2 largest of the planets in the solar system. Saturn draws attention to itself thanks to a system of rings formed from ice, rocks and dust that orbit the planet. There are three main rings with an outer diameter of 270,000 km, but their thickness is about 30 meters. 
The period of revolution around the Sun: 29 years 168 days.
Diameter of the planet at the equator: 120536 km.
Rotation period (turn around the axis): 10 hours 14 minutes.
Surface temperature: -180 degrees (average).
Atmosphere: mostly hydrogen and helium.
Number of satellites: 18 (+ rings).
Main satellites: Titan.
unique planet solar system. Its peculiarity is that it revolves around the Sun not like everyone else, but "lying on its side." Uranus also has rings, although they are harder to see. In 1986, Voyager 2 flew 64,000 km and had six hours of photography, which it successfully completed.
Orbital period: 84 years 4 days. Diameter at the equator: 51118 km.
The period of rotation of the planet (rotation around the axis): 17 hours 14 minutes.
Surface temperature: -214 degrees (average).
Atmosphere: mostly hydrogen and helium.
How many satellites: 15 (+ rings).
Main satellites: Titania, Oberon.
At the moment, Neptune is considered the last planet in the solar system. Its discovery took place by the method of mathematical calculations, and then they saw it through a telescope. In 1989, Voyager 2 flew by. He took amazing photographs of the blue surface of Neptune and its largest moon, Triton. 
The period of revolution around the Sun: 164 years 292 days.
Diameter at the equator: 50538 km.
Rotation period (turn around the axis): 16 hours 7 minutes.
Surface temperature: -220 degrees (average).
Atmosphere: mostly hydrogen and helium.
Number of satellites: 8.
Main moons: Triton.
On August 24, 2006, Pluto lost planetary status. The International Astronomical Union has decided which celestial body should be considered a planet. Pluto does not meet the requirements of the new formulation and loses its "planetary status", at the same time, Pluto passes into a new quality and becomes the prototype of a separate class of dwarf planets.
How did the planets appear? Approximately 5–6 billion years ago, one of the gas and dust clouds of our large Galaxy ( milky way), shaped like a disk, began to shrink towards the center, gradually forming the current Sun. Further, according to one of the theories, under the influence of powerful forces of attraction, a large number of dust and gas particles rotating around the Sun began to stick together into balls - forming future planets. According to another theory, the gas and dust cloud immediately broke up into separate clusters of particles, which compressed and condensed, forming the current planets. Now 8 planets revolve around the sun constantly.
Planets of the solar system
According to the official position of the International Astronomical Union (IAU), an organization that assigns names to astronomical objects, there are only 8 planets.
Pluto was removed from the category of planets in 2006. because in the Kuiper belt are objects that are larger / or equal in size to Pluto. Therefore, even if it is taken as a full-fledged celestial body, then it is necessary to add Eris to this category, which has almost the same size with Pluto.
As defined by MAC, 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 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, for ease of understanding, equated to the earth's year, is 88 days, while Mercury has time to complete a revolution around its own axis only one and a half times. Thus, its day lasts approximately 59 Earth days. For a long time it was believed that this planet was always turned to the Sun by the same side, since the periods of its visibility from the Earth were repeated with a frequency approximately equal to four Mercury days. This misconception was dispelled with the advent of the possibility of using radar research and conducting constant 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, as seen by the MESSENGER spacecraft
Mercury's proximity to the Sun has caused it to experience the largest temperature fluctuations of any of 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 have been identified in the atmosphere. There is a theory that it was previously a satellite of Venus, but so far this remains unproven. It has no satellites of its own.
Venus
The second planet from the Sun, the atmosphere of which consists almost entirely of carbon dioxide. She is often called 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 amounts.
Venus in the UV spectrum
Such an atmosphere creates a greenhouse effect, the temperature on the surface because of this is even higher than that of Mercury and reaches 475 ° C. Considered the slowest, the Venusian day lasts 243 Earth days, which is almost equal to a year on Venus - 225 Earth days. Many call it the sister of the Earth because of the mass and radius, the values of which are very close to the earth's indicators. The radius of Venus is 6052 km (0.85% of the earth). There are no satellites, like Mercury.
The third planet from the Sun and the only one in our system where there is liquid water, without which life on the planet could not develop. At least life as we know it. The radius of the Earth is 6371 km and, unlike the rest celestial bodies of our system, more than 70% of its surface is covered with water. The rest of the space is occupied by the 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 a change in the landscape. The speed of the planet moving along it is 29-30 km / s.
Our planet from space
One revolution around its axis takes almost 24 hours, and full walkthrough the orbit lasts 365 days, which is much longer in comparison with the nearest neighboring planets. The Earth day and year are also taken as a standard, but this is done only for the convenience of perceiving time intervals on other planets. The earth has one natural satellite- Moon.
Mars
The fourth planet from the Sun, known for its rarefied atmosphere. Since 1960, Mars has been actively explored by scientists from several countries, including the USSR and the USA. Not all research programs have been successful, but water found in some areas suggests that primitive life exists on Mars, or existed in the past.
The brightness of this planet allows you to see it from Earth without any instruments. Moreover, once every 15-17 years, during the Opposition, it becomes the brightest object in the sky, eclipsing even Jupiter and Venus.
The radius is almost half that of the 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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The 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 moon. Like the Moon, Mercury is practically devoid of an atmosphere and cannot smooth out the traces of impact from the fall of meteorites, therefore, like the Moon, it is covered with craters. The day side of Mercury is very hot on the Sun, and on the night side the temperature drops hundreds of degrees below zero. In the craters of Mercury, which are located at the poles, there is ice. Mercury makes one revolution around the Sun in 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 in a thick and toxic atmosphere that creates a strong greenhouse effect. This scorched world is hot enough to melt lead. Radar images through the mighty 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 such a way that life became possible.
Mars
Although details of the surface of Mars are difficult to see from Earth, telescope observations show that Mars has seasons and white spots at the poles. For decades, people have assumed that the bright and dark areas on Mars are patches of vegetation and that Mars might be a suitable place for life, and that water exists in the polar caps. When the Mariner 4 spacecraft flew by Mars in 1965, many of the scientists were shocked to see pictures of the bleak, cratered planet. Mars turned out to be a dead planet. More recent missions, however, have revealed that Mars holds many mysteries that have yet to be solved.
Jupiter
Jupiter is the most massive planet in our solar system, has four large moons and many small moons. Jupiter forms a kind of miniature solar system. To turn into a full-fledged star, Jupiter had to become 80 times more massive.
Saturn
Saturn is the most distant of the five planets that were known before the invention of the telescope. Like Jupiter, Saturn is made up mostly of hydrogen and helium. Its volume is 755 times 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 with 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
Nearly 4.5 billion kilometers from the Sun, distant Neptune rotates. It takes 165 years to complete one revolution around the Sun. It is invisible to the naked eye due to its vast distance from Earth. Interestingly, his 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 has long been considered the ninth planet. But after the discovery of Pluto-like worlds even further away, Pluto was reclassified as a dwarf planet in 2006.
The planets are giants
There are four gas giants located beyond the orbit of Mars: Jupiter, Saturn, Uranus, Neptune. They are in the outer solar system. They differ in 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 more earth and only 10 times smaller than the Sun. A year on Jupiter is not the longest in the solar system, lasting 4333 Earth days (incomplete 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 orbit of the planet, a fairly accurate and clear model of the solar system is needed. The largest of them are Callisto, Ganymede, Io and Europa. At the same time, Ganymede is the largest satellite of the planets in the entire solar system, its radius is 2634 km, which is 8% larger 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 largest in the solar system. In comparison with other planets, the composition is most similar to the Sun chemical elements. The surface radius 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 far 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 than it, but no less famous for this - 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 rest.
For a long time, the rings on Saturn were considered a unique phenomenon, inherent only to him. Only recently it was found that all gas giants have rings, but the rest 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.
