How do planets move?
With the naked eye, we can distinguish seven celestial bodies, the position of which relative to the stars changes.
The ancient astronomers called these celestial bodies planets (translated from Greek as "wanderers"), these include the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn.
How to determine the position of the sun relative to the stars? Just as the ancient Egyptians, Babylonians and Greeks did it, you need to observe the starry sky just before sunrise or just after sunset. This is how you can make sure that the Sun changes its position relative to the starry sky every day and shifts approximately 1 degree to the east. And exactly one year later, the Sun returns to its previous point relative to the location of the stars. Based on the results of these observations, the ecliptic is naturally determined - the visible trajectory of the Sun's movement between the stars.
While moving along the ecliptic, the Sun passes through 12 constellations: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. The belt along the ecliptic about 16 degrees wide, in which these constellations are enclosed, is called zodiac.
The sun during its visible movement along the ecliptic on the days of the equinox is at the celestial equator, and then gradually moves away from it. The greatest deviation in both directions from the celestial equator is approximately 23.5 degrees and is observed on the days of the solstices. The Greeks noticed that the speed of the Sun's apparent movement along the ecliptic in winter is slightly higher than in summer.
The rest of the planets, like the Sun, in addition to the daily movement to the west, also move to the east, but more slowly.
The moon moves eastward faster than the sun, and its trajectory is more chaotic. The Moon makes a full revolution along the zodiac from east to west in an average of 27 and one third of days. The time interval during which the moon makes a full revolution along the zodiac, moving from east to west, is called sidereal period of circulation.The sidereal period of the Moon's revolution can differ from the average period by as much as 7 hours. It was also noticed that the trajectory of the Moon in the starry sky at a certain moment coincides with the ecliptic, after which it gradually moves away from it until it reaches a maximum deviation of about 5 degrees, then again approaches the ecliptic and deviates from it at the same angle, but in the opposite direction.
Mercury, Venus, Mars, Jupiter and Saturn are the five planets that are visible in the starry sky as bright points. Their average sidereal orbital periods are: 1 year for Mercury, 1 year for Venus, 687 days for Mars, 12 years for Jupiter, and 29.5 years for Saturn. Actual orbital periods for all planets may differ from the reported average.
The movement of the planets from west to east is called direct or proper. The forward speed of these five planets is constantly changing.
In addition, it was an unexpected discovery that the direct movement of the planets to the east is periodically interrupted and the planets move in the opposite direction, that is, to the west. At this time, their trajectories form loops, after which the planets continue their direct motion again. During the reverse or reverse motion, the brightness of the planets increases. The illustration shows the backward motion of Venus, which begins every 584 days.
Mercury starts backward movement every 116 days, Mars every 780 days, Jupiter every 399 days, Saturn every 378 days.
Mercury and Venus never move a significant angular distance from the Sun, unlike Mars, Jupiter and Saturn.
It should be noted that it was so difficult to link the movement of planets with the movement of stars that the entire history of the development of ideas about the world can be considered as successive attempts to overcome the observed discrepancies
The study of the apparent motion of the planets against an unchanging background of the starry sky made it possible to give a complete kinematic description of the motion of the planets relative to the inertial reference frame of the Sun - the star. The trajectories of the planets turned out to be closed curves, called orbits. The orbits are close to circles with the center in the Sun, and the motion of the planets in orbits turned out to be close to uniform. The only exceptions are comets and some asteroids, the distance from which to the Sun and the speed of movement of which vary widely, and the orbits are highly elongated. The distances from the planets to the Sun (orbital radii) and the times of revolution of these planets around the Sun are very different (Table 2). The designations of the first six planets given in the table have been preserved since the time of astrologers.
Table 2. Information about the planets
|
Name and designation of the planet |
Distance from the Sun |
Time of circulation in earth years |
|
|
In the radii of the earth's orbit |
In million km |
||
|
Mercury Land (or) |
|||
In reality, the orbits of the planets are not completely circular, and their speeds are not completely constant. An accurate description of the motions of all planets was given by the German astronomer Johannes Kepler (1571-1630) - at his time only the first six planets were known - in the form of three laws (Fig. 199).
1. Each planet moves along an ellipse, in one of the focuses of which is the Sun.
2. The radius vector of the planet (a vector drawn from the Sun to the planet) describes equal areas at equal times.
3. The squares of the orbital times of any two planets are referred to as cubes of the semi-major axes of their orbits.
From these laws, a number of conclusions can be drawn about the forces under the influence of which the planets move. Let us first consider the movement of any one planet. The end of the major axis of the orbit closest to the Sun () is called perihelion; the other end is called the aphelion (fig. 200). Since the ellipse is symmetrical about both of its axes, the radii of curvature at perihelion and aphelion are equal. So, according to what was said in § 27, normal accelerations at these points are related as squares of the planet's velocities and:
(123.1)
Figure: 199. If the planet moves from point to point in the same time as from point to point, then the areas shaded in the figure are equal
Figure: 200. To determine the ratio of the planet's velocities at perihelion and aphelion
Consider the small paths and, symmetric with respect to the perihelion and aphelion and made for the same time intervals. According to Kepler's second law, the areas of the sectors and must be equal. The arcs of the ellipse and are equal to and. In Fig. 200, the arcs are made quite large for clarity. If we take these arcs extremely small (for which the time interval must be small), then the difference between the arc and the chord can be neglected and the sectors described by the radius vector can be considered as isosceles triangles and. Their areas are equal, respectively, and, where and are the distances from aphelion and perihelion to the Sun. Hence, whence 
... Finally, substituting this relation in (123.1), we find
. (123.2)
Since at perihelion and aphelion tangential accelerations are equal to zero, then they represent the acceleration of the planet at these points. They are directed towards the Sun (along the major axis of the orbit).
The calculation shows that at all other points of the trajectory the acceleration is directed towards the Sun and changes according to the same law, that is, inversely proportional to the square of the planet's distance from the Sun; therefore, for any point of the orbit
where is the acceleration of the planet, is the distance from it to the Sun. Thus, the acceleration of a planet is inversely proportional to the square of the distance between the Sun and the planet. Considering the angle made by the radius vector of the planet with a tangent to the trajectory, we see (Fig. 201) that when the planet moves from aphelion to perihelion, the tangential component of the acceleration, the positive velocity of the planet, increases; on the contrary, when moving from perihelion to aphelion, the planet's speed decreases. At perihelion the planet reaches the highest speed, at aphelion - the lowest speed of movement.
To clarify the dependence of the acceleration of the planet on its distance from the Sun, we used the first two Kepler's laws. This dependence was found because the planets move in ellipses, changing their distance from the Sun. If the planets moved in circles, the distance from the planet to the Sun and its acceleration would not change, and we would not be able to find this relationship.
Figure: 201. When the planet moves from perihelion to aphelion, the force of gravity decreases the planet's speed, when moving from aphelion to perihelion, it increases the planet's speed
But when comparing the accelerations of various planets, one can be satisfied with an approximate description of the motion of the planets, assuming that they move uniformly in circles. Let us denote the radii of the orbits of some two planets by and, and the periods of their revolution by
Substituting the ratio of the squares of the orbital times into formula (123.4), we find
This conclusion can be rewritten as follows: for any planet located at a distance from the Sun, its acceleration
where is the same constant for all planets of the solar system. Thus, the accelerations of the planets are inversely proportional to the squares of their distances from the Sun and are directed towards the Sun.
Experienced astronomers are well aware of the fact that the orbital speed of the planets is directly related to their distance from the center of the system - the Sun. Well, and people who are just starting to study the amazing science of celestial bodies would probably be interested to learn more about it.
What is Orbital Velocity?
An orbit is the trajectory along which a particular planet moves around the sun. It does not at all represent a perfect circle, as some people who are not versed in astronomy think. Moreover, it does not even resemble an oval too much - after all, there are a large number of factors, with the exception of the gravitational force of the Sun, that can affect the movement of celestial bodies.
It is also worth immediately dispelling another well-known myth - the sun is not always exactly in the center of the orbits of the planets revolving around it.
Finally, it should be noted that not all the orbits of the planets lie in the same plane. Some are significantly knocked out of it - for example, if you depict the standard orbits of the Earth and Venus on an astronomical map, you can make sure that they have only a few points of intersection.
Now that we have more or less sorted out with orbits, we can return to the definition of the term for the orbital velocity of planets. This is what astronomers call the speed at which the planet moves along its trajectory. It may change slightly - depending on which celestial bodies pass nearby. This is especially noticeable in the example of Mars: every time it passes in relative proximity to Jupiter, it slows down a little, being attracted by the gravitational field of this giant.
Scientists have long established the dependence of the speed of movement of the planets around the Sun on the distance to it.
That is, the planet closest to the Sun - Mercury - moves the fastest, while Pluto's speed is the smallest in the solar system.
What is the reason for this?
The fact is that the speed of each planet corresponds to the force with which the Sun attracts it at a certain distance. If the speed is less, then the planet will gradually approach the star and as a result will burn up. If the speed is too high, then the planet will simply fly away from the center of our solar system.
Every astronomer, even a beginner, knows perfectly well that the force of gravity decreases with distance from the Sun. That is why, in order to maintain its place in the solar system, Mercury is forced to rush at a breakneck speed, Mars can move more slowly, and Pluto barely moves at all.
Mercury
The planet closest to the Sun is Mercury. Here we will begin the study of the speed of the planets of the solar system.
It boasts not only the smallest orbital radius, but also small size. In our system, this is the smallest full-fledged planet. The distance from Mercury to the Sun is less than 58 million kilometers, due to which the temperature at its equator on a hot day can rise to 400 degrees Celsius and even more.
In addition, in order to stay in its orbit with the Sun so close, the planet has to move at a tremendous speed - about 47 kilometers per second. Since the length of the orbit is very small due to the small radius, it makes a complete revolution around the star in just 88 days. That is, the New Year can be celebrated there much more often than on Earth. But the speed of rotation of the planet around its own axis is very small - Mercury makes a full revolution in almost 59 Earth days. So, the day here is not much shorter than a year.
Venus
The next planet in our system is Venus. The only one on which the Sun rises in the west and sets in the east. The distance to the center of the system is 108 million kilometers. Due to this, the speed of movement of the planet in orbit is much lower than that of Mercury (only 35 kilometers per second). Moreover, this is the only planet whose orbit is really an almost perfect circle - the error (or, as experts say, eccentricity) is extremely small.
True, the length of its orbit (in comparison with Mercury) is much longer, which is why Venus makes a full path in only 225 days. By the way, another interesting fact that distinguishes Venus from all other planets of the solar system: the period of rotation around the axis (one day) here is 243 Earth days. Consequently, the year here lasts less than a day.
Earth
Now you can consider the planet that has become the home for humanity - the Earth. The average distance to the Sun is nearly 150 million kilometers. It is this distance that is usually called one astronomical unit - they are used when calculating small (by the standards of the Universe) distances in space.
Believe it or not, while you are reading this article, you are moving with the Earth at a speed of almost 30 kilometers per second. But even at such an impressive speed, the planet spends more than 365 days or 1 year to make a complete revolution around the Sun. But it rotates around its axis quite quickly - in just 24 hours. However, these and many other facts about the Earth are obvious to everyone, so we will not consider our home planet in detail. Let's go straight to the next one.
Mars
This planet is named after the formidable god of war. In all respects, Mars is as close as possible to Earth. For example, the planet's orbital speed is 24 kilometers per second. The distance to the Sun is about 228 million kilometers, which is why it is quite cool on the surface most of the time - only during the day it warms up to -5 degrees Celsius, and at night it gets colder to -87 degrees.
But the day here is practically equal to that of the earth - 24 hours and 40 minutes. For simplicity, a new term was even coined for the Martian day - sol.
Since the distance to the Sun is quite large, and the trajectory of motion is much longer than that of the Earth, the year here lasts quite a long time - as much as 687 days.
The eccentricity of the planet is not too large - about 0.09, so the orbit can be considered conditionally round with the Sun located almost in the center of the circumscribed circle.
Jupiter
Jupiter got its name in honor of the most powerful ancient Roman god. It is not surprising that this particular planet can boast of the largest dimensions in the solar system - its radius is almost 70 thousand square kilometers (the Earth, for example, has only 6 371 kilometers).
The distance from the Sun allows Jupiter to rotate rather slowly - only 13 kilometers per second. Because of this, it takes the planet almost 12 Earth years to complete a circle!
But the day here is the shortest in our system - 9 hours and 50 minutes. The tilt of the axis of rotation is extremely small here - only 3 degrees. For comparison, our planet has this figure of 23 degrees. Because of this, there are absolutely no seasons on Jupiter. The temperature is always the same, changing only for short days.
Jupiter's eccentricity is quite small - less than 0.05. Therefore, he uniformly winds circles strictly around the Sun.
Saturn
This planet is not too inferior to Jupiter in size, being the second largest cosmic body in our solar system. Its radius is 58 thousand kilometers.
The speed of the planet in orbit, as mentioned above, continues to fall. For Saturn, this figure is only 9.7 kilometers per hour. And it takes a really great distance to travel at such a low speed - the distance to the Sun is almost 9.6 astronomical units. In total, this path takes 29.5 years. But the day is one of the shortest in the system - only 10.5 hours.
The eccentricity of the planet is almost the same as that of Jupiter - 0.056. Therefore, the circle turns out to be quite even - perihelion and aphelion differ by only 162 million kilometers. Considering the huge distance to the Sun, the difference is very small.
Interestingly, Saturn's rings also revolve around the planet. Moreover, the speed of the outer layers is much less than that of the inner ones.
Uranus
Another giant of the solar system. Only Jupiter and Saturn surpass it in size. True, Neptune also bypasses it in weight, but this is due to the high density of the core. The average distance to the Sun is really huge - as many as 19 astronomical units. It moves rather slowly - it can quite afford it at such a great distance. The planet's orbital speed does not exceed 7 kilometers per hour. Because of this slow pace, it takes 84 Earth years for Uranus to travel a huge distance around the Sun! A very decent time.
But around its axis, it rotates surprisingly quickly - a full revolution is completed in just 18 hours!
An amazing feature of the planet is that it rotates around itself not vertically, but horizontally. In other words, all other planets in the solar system make a revolution "standing" at the pole, and Uranus simply "rolls" in its orbit, as if lying on its side. Scientists explain this by the fact that during the formation of the planet, it collided with some kind of large cosmic body, because of which it simply fell on its side. Therefore, although in the generally accepted sense the day here is very short, at the poles the day lasts 42 years, and then the night stands for the same number of years.
Neptune
The ancient Roman ruler of the seas and oceans gave Neptune its proud name. No wonder even his trident became the symbol of the planet. In size, Neptune is the fourth planet in the solar system, only slightly inferior to Uranus - its average radius is 24,600 km versus 25,400.
It is kept at an average distance of 4.5 billion kilometers from the Sun, or 30 astronomical units. Therefore, the path that he makes, passing the orbit, is really huge. And if we consider that the circular speed of the planet is only 5.4 kilometers per second, then there is nothing surprising in the fact that one year here is equal to 165 Earth years.
An interesting fact: there is a rather dense atmosphere here (although it consists mainly of methane), and sometimes there are winds of amazing strength. Their speed can reach 2100 kilometers per hour - on Earth, even a single gust of such power would instantly destroy any city, leaving no stone unturned.
Pluto
Finally, the last planet on our list. More precisely, not even a planet, but a planetoid - recently it was deleted from the list of planets due to its small size. The average radius is only 1187 kilometers - even for our Moon this figure is 1737 kilometers. Nevertheless, its name is rather formidable - it was appropriated in honor of the god of the underworld of the dead among the ancient Romans.
The average distance from Pluto to the Sun is about 32 astronomical units. This allows him to feel safe and move at a speed of only 4.7 kilometers per second - Pluto will not fall on the red-hot star anyway. But to make a complete revolution around the Sun with such a huge radius, this tiny planet spends 248 Earth years.
It also rotates very slowly around its axis - it takes 152 Earth hours or more than 6 days.
In addition, the eccentricity is the largest in the solar system - 0.25. Therefore, the Sun is far from the center of the orbit, but is displaced by almost a quarter.
Conclusion
This concludes the article. Now you know about the speed of the planets in our solar system, as well as many other factors. Surely now you understand astronomy much better than before.
solar system - these are 8 planets and more than 63 of their satellites, which are opening more and more often, several dozen comets and a large number of asteroids. All cosmic bodies move along their clear directional trajectories around the Sun, which is 1000 times heavier than all bodies in the solar system combined. The center of the solar system is the Sun - the star around which the planets revolve in orbits. They do not emit heat and do not glow, but only reflect the light of the Sun. There are now 8 officially recognized planets in the solar system. Briefly, in order of distance from the sun, we list them all. And now a few definitions.
Planet Is a celestial body that must satisfy four conditions:
1.the body must revolve around the star (for example, around the sun);
2. the body must have sufficient gravity to be spherical or close to it;
3. the body should not have other large bodies near its orbit;
4.the body shouldn't be a star
Satellites of the planets. The solar system also includes the Moon and natural satellites of other planets, which all of them have, except for Mercury and Venus. More than 60 satellites are known. Most of the satellites of the outer planets were discovered when they received photographs taken by robotic spacecraft. The smallest satellite of Jupiter - Leda - is only 10 km across.
Is a star, without which life on Earth could not exist. She gives us energy and warmth. According to the classification of stars, the Sun is a yellow dwarf. Age about 5 billion years. It has a diameter at the equator equal to 1,392,000 km, 109 times larger than Earth's. The rotation period at the equator is 25.4 days and 34 days at the poles. The mass of the Sun is 2x10, 27 tons, about 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. In terms of chemical composition, the Sun consists of 75% hydrogen, and of the other 25% of the elements, most of all helium. Now, in order, let's figure out how many planets revolve around the sun, in the solar system and the characteristics of the planets.
The four inner planets (closest 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.
The period of revolution around the Sun: 87.97 days. Diameter at the equator: 4878 km.
Rotation period (rotation around the axis): 58 days.
Surface temperature: 350 during the day and -170 at night.
Atmosphere: very thin, helium.
How many satellites: 0.
The main satellites of the planet: 0.
More like Earth in size and brightness. Observing her is difficult because of the clouds that envelop her. The surface is a hot rocky desert. 
The period of revolution around the Sun: 224.7 days.
Diameter at the equator: 12104 km.
Rotation period (revolution around the axis): 243 days.
Surface temperature: 480 degrees (average).
Atmosphere: dense, mainly 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 "grew" the planet. Surface temperatures reached 5,000 degrees Celsius. Then the Earth cooled down and was covered with hard stone crust. But the temperature in the bowels is still quite high - 4500 degrees. Rocks in the depths are melted and, during volcanic eruptions, are poured onto the surface. Only on earth there is water. Therefore, life exists here. It is located relatively close to the Sun in order to receive the necessary heat and light, but far enough so as not to burn out.
The period of revolution around the Sun: 365.3 days. Diameter at the equator: 12756 km.
The period of the planet's rotation (revolution around the axis): 23 hours 56 minutes.
Surface temperature: 22 degrees (average).
Atmosphere: Mainly nitrogen and oxygen.
Number of satellites: 1.
The main satellites of the planet: the Moon.
Due to the resemblance to Earth, it was believed that life exists here. But the spacecraft that landed on the surface of Mars showed no signs of life. This is the fourth planet in order. 
The period of revolution around the Sun: 687 days.
Diameter of the planet at the equator: 6794 km.
Rotation period (revolution around the axis): 24 hours 37 minutes.
Surface temperature: –23 degrees (average).
Atmosphere of the planet: rarefied, mainly carbon dioxide.
How many satellites: 2.
The main satellites in order: Phobos, Deimos.
Jupiter, Saturn, Uranus and Neptune are composed of hydrogen and other gases. Jupiter is more than 10 times the diameter of Earth, 300 times its mass and 1300 times its volume. It is more than twice as massive as all the planets in the solar system combined. How long does it take for the planet Jupiter to become a star? We need to increase its mass 75 times!
The period of revolution around the Sun: 11 years 314 days. Diameter of the planet at the equator: 143884 km
Rotation period (revolution around the axis): 9 hours 55 minutes.
The 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.
It is the number 2 largest planet in the solar system. Saturn is eye-catching thanks to its ring system made of ice, rocks and dust that orbits 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: 120,536 km.
Rotation period (revolution around the axis): 10 hours 14 minutes.
Surface temperature: -180 degrees (average).
Atmosphere: Mainly hydrogen and helium.
Number of satellites: 18 (+ rings).
Main satellites: Titan.
Unique planet in the 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 at a distance of 64,000 km, he had six hours of photography, which he successfully implemented.
Circulation period: 84 years 4 days. Diameter at the equator: 51,118 km.
The period of the planet's rotation (revolution around the axis): 17 hours 14 minutes.
Surface temperature: –214 degrees (average).
Atmosphere: Mainly 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 means of mathematical calculations, and then they saw it through a telescope. In 1989, Voyager 2 flew by. He captured striking 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.
Period of rotation (revolution around the axis): 16 hours 7 minutes.
Surface temperature: –220 degrees (average).
Atmosphere: Mainly hydrogen and helium.
Number of satellites: 8.
Main satellites: Triton.
On August 24, 2006, Pluto lost its planetary status. The International Astronomical Union made a decision on 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 the planets appeared. Approximately 5-6 billion years ago, one of the disk-shaped gas and dust clouds of our large Galaxy (Milky Way) began to collapse towards the center, gradually forming the present Sun. Further, according to one of the theories, under the influence of powerful gravitational forces, 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-dust cloud immediately disintegrated into separate clusters of particles, which were compressed and compressed, forming the present planets. Now 8 planets revolve around the Sun constantly.
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 together 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.
In the center of the solar system is the Sun, around which nine large planets revolve in orbits. Since the Sun is displaced from the center of 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:
Terrestrial planets: and ... These planets are small in size with a rocky surface, they are closer to the Sun than others.
Planets giants: and ... They are large planets, mostly made of gas, and are characterized by rings of ice dust and many rocky pieces.
But does not fall into any group, because, despite its location in the solar system, it is too far from the sun and has a very small diameter, only 2320 km, which is half the diameter of Mercury.
The 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.
Jupiter's rings and moons: 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 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 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, so they were discovered not so long ago in 1977 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. An interesting fact is that the satellite Triton has the opposite direction of orbital motion; strange volcanoes were also discovered on the satellite, which spewed nitrogen gas, like geysers, spreading a dark mass (from a liquid state to vapor) for many kilometers into the atmosphere. During its mission, Voyager 2 discovered six more satellites of the planet Neptune ...