The planet Saturn is one of the brightest objects in our starry sky. Its distinctive feature is the presence of rings. G. Galileo saw them for the first time in 1610, but did not understand what they were, writing down that Saturn consists of parts.
Half a century later, the Dutch mathematician, physicist and astronomer Christian Huygens(1629-1695) reported the presence of a ring on Saturn, and in 1675 the famous Italian and French astronomer Jean Dominique Cassini(1625-1712) discovered a gap between the rings.
These rings are visible from Earth even through a small telescope. They are made up of thousands and thousands of small hard pieces of rock and ice that orbit the planet. Once every 14-15 years, the rings of Saturn are not visible from the Earth, as they turn edge-on.
General characteristics of the planet Saturn
Therefore, Saturn is not a solid ball, but consists of gas and liquid, its equatorial parts rotate faster than the polar regions: at the poles, one revolution is approximately 26 minutes slower.
One of the features of Saturn is that it is the only planet in the solar system whose density is less than that of water. Saturn's atmosphere is very dense, consisting of 94% hydrogen and 6% helium. The temperature on the surface of the planet is 150 °C.
The speed of the winds on Saturn depends on the latitude of the place, reaching 500 m/s, which is three times more than on Jupiter. Storms are often observed in Saturn's atmosphere, although not as powerful as Jupiter's famous Red Spot. In particular, the Great Brown Spot has been discovered on Saturn.
The planet has eight large main and many small satellites.
Most satellites are made of ice: their density does not exceed 1400 kg/m3. The largest satellites form a rocky core. Almost all satellites are always turned to the planet on one side.
The largest moon of Saturn is Titan. It is larger than the planet Mercury. Its diameter is 5150 km. It was discovered in 1655 by Christian Huygens. Titan has oceans, seas, continents. The temperature is 180 °C. This moon is shrouded in an orange atmosphere of methane and ethane.
The moon Enceladus is the brightest body in the solar system, which, apparently, is covered with a thin layer of frost. The two largest craters on this moon of Saturn are named after Ali Baba and Aladdin.
Hyperion is a dark, irregularly shaped satellite with a chaotic rotation of its own. It does not have a constant speed of rotation around its axis: it changes during the month by tens of percent.
Saturn's moon Phoebe revolves around the planet in the opposite direction.
Saturn is the sixth planet from the Sun and the second largest planet in the solar system in terms of diameter and mass. Often, Saturn is called sister planets. When compared, it becomes clear why Saturn and Jupiter were designated as relatives. From the composition of the atmosphere to the features of rotation, these two planets are very similar. It is in honor of this similarity that in Roman mythology Saturn was named after the father of the god Jupiter.
A unique feature of Saturn is the fact that this planet is the least dense in the solar system. Despite having a dense, solid core, Saturn's large, gaseous outer layer brings the planet's average density to only 687 kg/m3. As a result, it turns out that the density of Saturn is less than that of water, and if it were the size of a matchbox, it would easily float along the spring stream.
Orbit and rotation of Saturn
The average orbital distance of Saturn is 1.43 x 109 km. This means that Saturn is 9.5 times farther from the Sun than the total distance from the Earth to the Sun. As a result, it takes about an hour and twenty minutes for sunlight to reach the planet. In addition, given the distance of Saturn from the Sun, the duration of the year on the planet is 10.756 Earth days; that is, about 29.5 Earth years.
The eccentricity of Saturn's orbit is the third largest after and. As a result of such a large eccentricity, the distance between the planet's perihelion (1.35 x 109 km) and aphelion (1.50 x 109 km) is quite significant - about 1.54 x 108 km.
Saturn's 26.73-degree axial tilt is very similar to Earth's, which explains why the planet has the same seasons as Earth. However, due to Saturn's distance from the Sun, it receives significantly less sunlight throughout the year, and for this reason, the seasons on Saturn are much more "blurred" than on Earth.
Talking about the rotation of Saturn is just as interesting as talking about the rotation of Jupiter. With a rotation speed of approximately 10 hours and 45 minutes, Saturn is second only to Jupiter, which is the fastest rotating planet in the solar system. Such extreme rates of rotation no doubt affect the shape of the planet, giving it the shape of a spheroid, that is, a sphere that bulges somewhat around the equator.
The second surprising feature of Saturn's rotation is the different rotation rates between different apparent latitudes. This phenomenon is formed as a result of the fact that the predominant substance in the composition of Saturn is gas, and not a solid body.
Saturn's ring system is the most famous in the solar system. The rings themselves are mostly made up of billions of tiny particles of ice, along with dust and other comical debris. This composition explains why the rings are visible from Earth through telescopes - ice has a very high reflectance of sunlight.
There are seven broad classifications among the rings: A, B, C, D, E, F, G. Each ring is named according to the English alphabet, in order of frequency of discovery. The most visible rings from Earth are A, B and C. In fact, each ring is thousands of smaller rings, literally pressed against each other. But there are gaps between the main rings. The gap between rings A and B is the largest of these gaps and is 4700 km.
The main rings begin at a distance of about 7,000 km above Saturn's equator and extend for another 73,000 km. It is interesting to note that, despite the fact that this is a very significant radius, the actual thickness of the rings is no more than one kilometer.
The most common theory to explain the formation of rings is the theory that in the orbit of Saturn, under the influence of tidal forces, a medium-sized satellite broke up, and this happened at the moment when its orbit became too close to Saturn.
- Saturn is the sixth planet from the Sun and the last of the planets known to ancient civilizations. It is believed that it was first observed by the inhabitants of Babylon.
Saturn is one of the five planets that can be seen with the naked eye. It is also the fifth brightest object in the solar system.
In Roman mythology, Saturn was the father of Jupiter, the king of the gods. A similar ratio has in terms of the similarity of the planets with the same name, in particular in size and composition.
Saturn releases more energy than it receives from the Sun. It is believed that this feature is due to the gravitational contraction of the planet and the friction of a large amount of helium in its atmosphere.
Saturn takes 29.4 Earth years to complete its orbit around the Sun. Such a slow movement relative to the stars was the reason for the ancient Assyrians to designate the planet as "Lubadsagush", which means "the oldest of the old."
Saturn has some of the fastest winds in our solar system. The speed of these winds has been measured, the maximum figure is about 1800 kilometers per hour.
Saturn is the least dense planet in the solar system. The planet is mostly hydrogen and has a density less than that of water - which technically means that Saturn will float.
Saturn has over 150 moons. All of these satellites have an icy surface. The largest of these are Titan and Rhea. Enceladus is a very interesting satellite, as scientists are sure that a water ocean is hidden under its ice crust.
- Saturn's moon Titan is the second largest moon in the solar system, after Jupiter's moon Ganymede. Titan has a complex and dense atmosphere composed primarily of nitrogen, water ice, and rock. The frozen surface of Titan has liquid lakes of methane and a topography covered in liquid nitrogen. Because of this, researchers believe that if Titan is a harbor for life, then this life will be fundamentally different from the earth.
Saturn is the flattest of the eight planets. Its polar diameter is 90% of its equatorial diameter. This is due to the fact that the low-density planet has a high rotation rate - it takes Saturn 10 hours and 34 minutes to rotate around its axis.
On Saturn, oval-shaped storms occur, which are similar in structure to those that occur on Jupiter. Scientists believe that this pattern of clouds around the north pole of Saturn may be a real example of the existence of atmospheric waves in the upper clouds. Also above the south pole of Saturn there is a vortex, which in its form is very similar to the hurricane storms that occur on Earth.
In telescope lenses, Saturn is usually seen in a pale yellow color. This is because its upper atmosphere contains ammonia crystals. Below this top layer are clouds that are mostly water ice. Even lower, layers of icy sulfur and cold mixtures of hydrogen.
In ancient mythology, the planet Saturn was the divine father of Jupiter. Saturn was the god of Time and Fate. It is believed that Jupiter in his mythical guise went much further than his father. Saturn also belongs to the 2nd role among the planets in the solar system. Saturn is the 2nd in both mass and size. But despite this, it is behind most of the bodies of the solar system in terms of density.
Saturn, not wanting to put up with lagging behind Jupiter, settled down with a huge number of satellites and, most importantly, a beautiful ring, thanks to which the 6th planet seriously claims to be the first in the fight for the title of "Magnificence". Because of this, a lot of astronomy books prefer to place Saturn on their covers, and not Jupiter.
The planet Saturn has the ability to reach a negative stellar magnitude during the opposition of the planet. In simple telescopes, you can easily see the disk and the ring, if it is at least slightly turned towards the Earth. The ring, due to the movement of the planet in orbit, changes its orientation with respect to the Earth. When the plane of the ring crosses the Earth, it is almost impossible to see it even with good telescopes: it is very thin. Then the ring turns more and more towards us, and the planet, accordingly, becomes brighter and brighter with each new confrontation. In the 1st year, already close, the third millennium, on the day of opposition on December 3rd, Saturn will flare up to -0.45 magnitude. This year, the rings will turn to the Earth as much as possible.
What else can you see when looking at Saturn? Titan is the largest moon. It has a brightness of the order of magnitude 8.5. Because of the low contrast, Saturn's clouds are harder to see than Jupiter's cloud bands. But it is easy to determine the compression of the planet at the poles, which reaches 1:10.
Saturn was visited by 3 spacecraft that had previously visited Jupiter: Pioneer 11, Voyager 1 and Voyager 2.
General information
The planet Saturn is probably the most beautiful planet when looking at it through a telescope or studying pictures of Voyagers. Fairy rings cannot be confused with any other objects in the solar system. The planet has been known since ancient times. The maximum apparent magnitude is +0.7m. This planet is one of the brightest objects in our starry sky. Its dim white light created a bad name for the planet: a birth under the sign of Saturn has long been considered a bad omen.
The rings are visible from Earth through a small telescope. They are made up of thousands and thousands of small hard pieces of rock and ice that orbit the planet.
The period of rotation around the axis - sidereal day - is 10 hours 14 minutes (at latitudes up to 30 °). Since Saturn is not a solid ball, but consists of gas and liquid, its equatorial parts rotate faster than the polar regions: at the poles, one revolution is about 26 minutes slower. The average period of revolution around the axis is 10 hours 40 minutes.
Saturn has one interesting feature: it is the only planet in the solar system whose density is less than that of water (700 kg per cubic meter). If it were possible to create a huge ocean, Saturn could swim in it! In terms of internal structure and composition, Saturn strongly resembles Jupiter. In particular, on Saturn in the equatorial region there is also a Red Spot, although it is smaller than on Jupiter.
Two-thirds of the planet is made up of hydrogen. At a depth approximately equal to R / 2, that is, half the radius of the planet, hydrogen at a pressure of about 300 GPa passes into the metallic phase. As the depth increases further, starting from R/3, the proportion of hydrogen and oxide compounds increases. In the center of the planet (in the core region) the temperature is about 20,000 K.
Anyone who has observed the planets through a telescope knows that on the surface of Saturn, that is, at the upper boundary of its cloud cover, there are noticeably few details and their contrast with the surrounding background is small. In this it differs from Jupiter, where there are many contrasting details in the form of dark and light stripes, waves, knots, indicating a significant activity of its atmosphere.
The question arises whether the atmospheric activity of Saturn (for example, wind speed) is lower than that of Jupiter, or whether the details of its cloud cover are simply less visible from Earth due to the greater distance (about 1.5 billion km.) And more poor illumination by the Sun (almost 3.5 times weaker than the illumination of Jupiter)?
The Voyagers were able to obtain images of the cloud cover, which clearly capture the pattern of atmospheric circulation: dozens of cloud belts stretching along the parallels, as well as individual eddies. In particular, an analogue of the Great Red Spot of Jupiter was discovered, although smaller. It has been established that wind speeds on Saturn are even higher than on Jupiter: at the equator 480 m/s, or 1700 km/h. The number of cloud belts is greater than on Jupiter, and they reach higher latitudes. Thus, cloud images demonstrate the peculiarity of Saturn's atmosphere, which is even more active than Jupiter's.
Meteorological phenomena occur at a lower temperature than in the earth's atmosphere. Since Saturn is 9.5 times farther from the Sun than the Earth, it receives 9.5 = 90 times less heat. The temperature of the planet at the level of the upper boundary of the cloud cover, where the pressure is 0.1 atm, is only 85 K, or -188 C. It is interesting that even such a temperature cannot be obtained due to heating by the Sun alone. The calculation shows that the bowels of Saturn have their own source of heat, the flow from which is 2.5 times greater than from the Sun. The sum of these two streams gives the observed temperature of the planet.
The spacecraft have studied in detail the chemical composition of Saturn's overcloud atmosphere. In the main, it consists of almost 89% hydrogen. In second place is helium (about 11% by weight). Helium deficiency is explained by the gravitational separation of helium and hydrogen in the bowels of the planet: helium, which is heavier, gradually settles to great depths (which, by the way, releases part of the energy that "warms up" Saturn). Other gases in the atmosphere - methane, ammonia, ethane, acetylene, phosphine - are present in small quantities. Methane at such a low temperature (about -188 ° C) is mainly in a drop-liquid state. It forms the cloud cover of Saturn.
As for the small contrast of details visible in the atmosphere, as discussed above, the reasons for this phenomenon are not yet completely clear. It has been suggested that a contrast-weakening haze of tiny solid particles is suspended in the atmosphere. But the observations of Voyager 2 refute this: the dark stripes on the planet's surface remained sharp and clear to the very edge of Saturn's disk, while in the presence of haze they would have become cloudy towards the edges due to the large number of particles in front of them. The data obtained from Voyager 1 helped to determine the equatorial radius with great accuracy. At the level of the top of the cloud cover, the equatorial radius is 60330 km. or 9.46 times more than the earth. The period of Saturn's revolution around the axis has also been specified: it completes one revolution in 10 hours 39.4 minutes - 2.25 times faster than the Earth. Such a rapid rotation has led to the fact that the compression of Saturn is much greater than that of the Earth. The equatorial radius of Saturn is 10% larger than the polar one.
Since Saturn is very similar to Jupiter in its physical properties, astronomers have suggested that it also has a fairly noticeable magnetic field. The absence of the magnetic bremsstrahlung observed from the Earth from the planet Saturn was explained by the influence of the rings.
Options
Saturn's elliptical orbit has an eccentricity of 0.0556 and a mean radius of 9.539 AU. (1427 million km). The maximum and minimum distances from the Sun are approximately 10 and 9 AU. Distances from the Earth vary from 1.2 to 1.6 billion km. The inclination of the planet's orbit to the plane of the ecliptic is 2°29.4". The angle between the planes of the equator and the orbit reaches 26°44". The planet Saturn moves in its orbit at an average speed of 2.64 km/s; The period of revolution around the Sun is 29.46 Earth years.
The planet does not have a clear solid surface, optical observations are hampered by the opacity of the atmosphere. For the equatorial and polar radii, the values of 60.27 thousand km and 53.5 thousand km are accepted. The average radius is 9.1 times greater than that of the Earth. In the earth's sky, the planet Saturn looks like a yellowish star, the brightness of which varies from zero to the first magnitude. The mass is 5.6850∙1026 kg, which is 95.1 times the mass of the Earth; in this case, the average density, equal to 0.68 g/cm3, is almost an order of magnitude less than the density of the Earth. The free fall acceleration near the surface at the equator is 9.06 m/s2.
The surface of Saturn (cloud layer), like Jupiter, does not rotate as a whole. Tropical regions in the atmosphere circulate with a period of 10 hours 14 minutes of Earth time, and at temperate latitudes this period is 26 minutes longer.
| Medium radius | 1.4294x109 km |
| Eccentricity | 0,0560 |
| Period of circulation | 29l 167d 6.7h |
| synodic period | 378.1 days |
| Average orbital speed | 9.46 km/s |
| Orbital inclination | 2.488° |
| Number of satellites | >50 |
| Equatorial diameter | 120.536 km |
| surface area | 4.38 x 1010 km² |
| Weight | 5.688 x 1026 kg |
| Average density | 0.69 g/cm³ |
| Acceleration of free fall at the surface | 9.05 m/s² |
| Equatorial rotation period | 10 h 13 m 59 s |
| Rotation period internal | 10 h 39 m 25 s |
| Tilt axis of rotation | 25.33° |
| Albedo | 0,47 |
| 2nd space speed | 35.5 km/s |
| Average temperature at cloud top level | 93K |
| Minimum surface temperature | 82K |
| Average surface temperature | 143K |
| Maximum surface temperature | n/a |
Internal structure
In terms of internal structure and composition, the planet Saturn strongly resembles Jupiter.
In the depths of the atmosphere, pressure and temperature increase, and hydrogen gradually turns into a liquid state. Apparently, there is no clear boundary separating gaseous hydrogen from liquid hydrogen. It should look like the continuous boiling of the global hydrogen ocean. At a depth of about 30 thousand km, hydrogen becomes metallic (and the pressure reaches about 3 million atmospheres). Protons and electrons in it exist separately and it is a good conductor of electricity. Powerful electric currents arising in a layer of metallic hydrogen generate a magnetic field of Saturn (much less powerful than that of Jupiter).
At a depth approximately equal to R / 2, that is, half the radius of the planet, hydrogen at a pressure of about 300 GPa passes into the metallic phase. As the depth increases further, starting from R/3, the proportion of hydrogen and oxide compounds increases. In the center of the planet there is a massive core (up to 20 Earth masses) made of stone, iron and, possibly ... ice (in the core area) with a temperature of about 20,000 K.
Where will ice come from in the center of Saturn, where the temperature is about 20 thousand degrees? After all, the crystalline form of water that is well known to us - ordinary ice - melts already at a temperature of 0 C at normal atmospheric pressure. Even "softer" are the crystalline forms of ammonia, methane, carbon dioxide, which scientists also call ice. For example, solid carbon dioxide (dry ice used in various variety shows) under normal conditions immediately turns into a gaseous state, bypassing the liquid stage.
But the same substance can form different crystal lattices. In particular, science knows crystalline modifications of water, which differ from each other no less than furnace soot - from diamond, which is chemically identical to it. For example, the so-called ice VII has a density almost twice that of ordinary ice, and at high pressures it can be heated up to several hundred degrees! Therefore, one should not be surprised that ice is present in the center of Saturn at a pressure of millions of atmospheres; in this case, a mixture of crystals of water, methane and ammonia.
Atmosphere
Light yellow Saturn outwardly looks more modest than its neighbor - orange Jupiter. It does not have such a colorful cloud cover, although the structure of the atmosphere is almost the same. The upper atmosphere is composed of 93% hydrogen (by volume) and 7% helium. There are impurities of methane, water vapor, ammonia and some other gases. Ammonia clouds in the upper part of the atmosphere are more powerful than those of Jupiter, which makes it not so "colored" and striped.
According to the Voyagers, the strongest winds in the solar system blow on the planet Saturn, the devices recorded air currents of 500 m/s. The winds blow mainly in an easterly direction (in the direction of axial rotation). Their strength weakens with distance from the equator; as we move away from the equator, westerly atmospheric currents also appear. A number of data indicate that the winds are not limited by the layer of upper clouds, they must spread inward, at least 2 thousand km. In addition, Voyager 2 measurements showed that the winds in the southern and northern hemispheres are symmetrical about the equator. There is an assumption that symmetrical flows are somehow connected under the layer of the visible atmosphere.
Although the spots of atmospheric vortices on Saturn are inferior in size to Jupiter's Great Red Spot, grandiose storms are also observed there, visible even from Earth.
Southern hemisphere of Saturn. "Dragon Hurricane", it is clearly visible in this near-IR image (artificial colors in the image). Examining the results obtained by Cassini, scientists discovered that the "Dragon Hurricane" is the cause of the mysterious flares in the radio range. We may be seeing a giant thunderstorm when radio noise is caused by high-voltage lightning discharges. Images transmitted by the Voyager 1 AMS revealed several dozen belts and zones, as well as various convective cloud formations: several hundred bright spots with a diameter of 2000 - 3000 km, brown oval-shaped formations ~10,000 km wide and a red oval cloud formation (spot) at 55°S sh. The length of the red spot is 11,000 km, it is approximately equal in size to the white oval formations on Jupiter. The red spot is relatively stable. It is surrounded by a dark ring. It is believed that it may represent the "top" of the convective cell. It is believed that the stripes in the atmosphere are due to temperature differences. The number of bands reaches several tens, that is, much more than observed from the Earth, and more than was found in the atmosphere of Jupiter. Scientists expected to find conditions on Saturn comparable to conditions on Jupiter, since the dominant factor in the meteorological phenomena of both planets is heating due to an internal heat source, and not the absorption of solar energy.
However, the atmospheres of Saturn and Jupiter turned out to be very different. For example, on Jupiter, the highest wind speeds were recorded along the borders of the bands, and on Saturn, along the central part of the bands, while there is practically no wind at the boundaries of the bands and zones. In the belts and zones of Jupiter's atmosphere, western and eastern flows alternate, which are separated by shear regions. In contrast, a westerly flow has been detected on the planet Saturn in a very wide band from 40° N. sh. up to 40°S sh. One hypothesis is that the winds are driven by the cyclic rise and fall of large clouds of ammonia. The southern polar region is relatively bright. A dark cap has been found in the northern polar region. Perhaps this indicates seasonal changes that were not expected. One temperature profile obtained for the northern hemisphere shows that dark spots correspond to a relatively high temperature, and large bright areas correspond to a slightly lower temperature.
New information has been obtained about a cloud of neutral hydrogen surrounding Saturn in the same plane in which the planet's rings lie and its satellites circulate. Previously, scientists assumed that this toroidal cloud is located along the orbit of Titan and has its source in the atmosphere of Titan, where methane dissociates with the release of hydrogen. However, the ultraviolet spectrometer of the AMS Voyager 1 showed that the cloud is not located along the orbit of Titan, but extends from a distance of 1.5 million km from Saturn (slightly further than the orbit of Titan) to a distance of 480 thousand km from it (the region of the orbit of Rhea ). The total mass of the cloud is 25,000 tons, which is consistent with the available theories; the density is only 10 atoms in 1 cm3. In the atmosphere, stable formations sometimes appear, which are super-powerful hurricanes. Similar objects are observed on other gas planets of the solar system. The giant "Great White Oval" appears about once every 30 years, the last time it was observed in 1990 (smaller hurricanes form more often).
Not fully understood today is such an atmospheric phenomenon as the "Giant Hexagon". It is a stable formation in the form of a regular hexagon with a diameter of 25 thousand kilometers, which surrounds the north pole of the planet.
Powerful lightning discharges, auroras, and ultraviolet radiation of hydrogen have been detected in the atmosphere.
"Giant Hexagon"
A giant hexagon is an atmospheric phenomenon on the planet Saturn that does not have a strict explanation today. It is a geometrically regular hexagon with a diameter of 25 thousand kilometers, located at the north pole. Apparently, the hexagon is a rather unusual whirlwind. The straight walls of the vortex go deep into the atmosphere at a distance of up to 100 km. When studying the vortex in infrared, light patches are observed, which are giant gaps in the cloud system, which extend for at least 75 km. deep into the atmosphere.
This structure was first seen in a series of images transmitted by Voyager 1 and Voyager 2. Since the object never completely fell into the frame and due to the poor quality of the images, no serious study of the hexagon followed. Real interest in the Giant Hexagon appeared after the transmission of its images by the Cassini apparatus. The fact that the object was seen again after the Voyager mission, which took place more than a quarter of a century ago, suggests that the hexagon is a fairly stable atmospheric formation.
The polar winter and a good viewing angle gave the specialists the opportunity to examine the deep structure of the hexagon. It is assumed that the hexagon is not associated with the auroral activity of the planet or its radio emission, despite the fact that the structure is located inside the auroral oval. At the same time, the object, according to Cassini, rotates synchronously with the rotation of the deep layers of the atmosphere and, possibly, synchronously with its internal parts. If the hexagon is stationary relative to the deep layers of Saturn (unlike the observed upper layers of the atmosphere at lower latitudes), it can serve as a reference in determining the true speed of rotation.
Now the main point of view about the nature of the phenomenon is the model according to which the Giant hexagon is a kind of stable wave surrounding the pole.
Space characteristics
During a flyby of Saturn, the Voyager 1 AMS discovered phenomena that, apparently, are intense bursts of radio emission in the region of the planet. The bursts occurred over the entire recorded frequency range and may have come from the rings of the planet. According to other assumptions, bursts could be generated by lightning in the atmosphere of the planet. AMS instruments recorded a voltage surge 106 times greater than what would have been caused by an equally distant lightning flash in the earth's atmosphere.
The ultraviolet spectrometer registered auroras in the southern polar region of Saturn, covering an area with a length of over 8000 km and comparable in intensity to such phenomena on Earth.
Magnetosphere
Until the first spacecraft reached Saturn, there were no observational data on its magnetic field at all, but from ground-based radio astronomy observations it followed that Jupiter has a powerful magnetic field. This was evidenced by non-thermal radio emission at decimeter waves, the source of which turned out to be larger than the visible disk of the planet, and it is extended along Jupiter's equator symmetrically with respect to the disk. This geometry, as well as the polarization of the radiation, indicated that the observed radiation is magnetic bremsstrahlung and its source is electrons captured by Jupiter's magnetic field and inhabiting its radiation belts, similar to those of the Earth. Flights to Jupiter confirmed these conclusions.
Since Saturn is very similar to Jupiter in its physical properties, astronomers have suggested that it also has a fairly noticeable magnetic field. The absence of the magnetic bremsstrahlung observed from the Earth was explained by the influence of the rings.
These suggestions have been confirmed. Even during the approach of Pioneer-11, its instruments registered formations in near-planetary space that are typical of a planet with a pronounced magnetic field: a bow shock wave, the boundary of the magnetosphere (magnetopause), and radiation belts. In general, the magnetosphere is very similar to the Earth's, but, of course, much larger in size. The outer radius of the magnetosphere at the subsolar point is 23 equatorial radii of the planet, and the distance to the shock wave is 26 radii.
Radiation belts are so extensive that they cover not only the rings, but also the orbits of some of the planet's inner satellites.
As expected, in the inner part of the radiation belts, which is "blocked" by Saturn's rings, the concentration of charged particles is much lower. The reason for this is easy to understand if we remember that in the radiation belts, particles oscillate approximately in the meridional direction, each time crossing the equator. But Saturn has rings in the plane of the equator: they absorb almost all particles that tend to pass through them. As a result, the inner part of the radiation belts, which in the absence of rings would be the most intense source of radio emission in the system, is weakened. Nevertheless, Voyager 1, approaching the planet, nevertheless detected non-thermal radio emission from its radiation belts.
The magnetic field is generated by electric currents in the bowels of the planet - apparently, in a layer where, under the influence of colossal pressures, hydrogen passed into a metallic state. When this layer rotates with the same angular velocity, the magnetic field also rotates.
Due to the high viscosity of the substance of the inner particles of the planet, they all rotate with the same period. Thus, the period of rotation of the magnetic field is at the same time the period of rotation of most of the mass (except for the atmosphere, which does not rotate like a solid body).
auroras
Saturn's auroras are caused by a high-energy outburst from the Sun that envelops the planet. The aurora can only be seen in ultraviolet light, which makes it difficult to see it from Earth.
This is an ultraviolet image of the aurora taken by the Space Telescope's 2D Spectrograph (STIS). The distance to Saturn is 1.3 billion km. The aurora borealis has the form of an annular curtain surrounding both magnetic poles of the planet. The curtain rises more than one and a half thousand kilometers above the surface of the clouds.
The auroras are similar to the earth's - both are associated with particles of the solar wind, which are captured by the planet's magnetic field as a trap and move along the lines of force from pole to pole back and forth. In the ultraviolet, the aurora is better distinguished from the background of the planet due to the strong luminescent glow of hydrogen.
The study began over 20 years ago: Pioneer 11 detected an increase in brightness near the poles in the far ultraviolet in 1979. Voyager 1 and 2 flybys in the early 1980s provided a general description of the aurora. This apparatus was the first to measure the magnetic field, which turned out to be very strong.
infrared glow
Known for its bright ring system and numerous moons, the gas giant Saturn looks strange and unfamiliar in this false-color image taken by the Cassini spacecraft. Indeed, in this composite image taken with a Visual and Infrared Mapping Spectrometer (VIMS), the famous rings are almost indistinguishable. They are seen edge-on and cross the center of the image.
The most spectacular contrast in the image is along the terminator, or the border of day and night. The blue-green hues on the right (on the day side) are visible sunlight reflected from the tops of the clouds. But to the left (on the night side) there is no sunlight, and in the infrared radiation of the warm inner parts of the planet, similar to the light of a Chinese lantern, silhouettes of details of deeper layers of clouds are visible. The thermal infrared glow is also visible in the shadows of the rings, which cross the northern hemisphere in wide bands.
ring system
Three rings are clearly visible from the Earth through a telescope: the outer, medium-brightness ring A; the middle, brightest ring B and the inner, dim, translucent ring C, which is sometimes called crepe. The rings are slightly whiter than the yellowish disk of Saturn. They are located in the plane of the planet's equator and are very thin: with a total width in the radial direction of about 60 thousand km. they are less than 3 km thick. Spectroscopically, it was found that the rings do not rotate like a solid body - with distance, the speed decreases. Moreover, each point of the rings has the same speed as a satellite would have at that distance, freely moving in a circular orbit.
From this it is clear that the rings are essentially a colossal accumulation of small solid particles that independently rotate around the planet. The particle sizes are so small that they are not visible not only in terrestrial telescopes, but also from spacecraft.
A characteristic feature of the structure of the rings is the dark annular spaces (divisions), where there is very little substance. The widest of them (3500 km) separates the B ring from the A ring and is called the "Cassini division" in honor of the astronomer who first saw it in 1675. Under exceptionally good atmospheric conditions, more than ten such divisions are visible from the Earth. Their nature, apparently, is resonant. Thus, the Cassini division is the region of orbits in which the period of revolution of each particle around the planet Saturn is exactly half that of the nearest large satellite, Mimas.
Because of this coincidence, Mimas, with its attraction, kind of shakes the particles moving inside the fission, and eventually ejects them from there. The onboard cameras of the Voyagers showed that from a close distance, the rings of Saturn look like a gramophone record: they seem to be stratified into thousands of individual narrow rings with dark clearings between them. There are so many gaps that it is no longer possible to explain their resonances with the periods of revolution of the satellites.
In addition to rings A, B and C, Voyagers discovered four more: D, E, F and G. All of them are very rarefied and therefore dim. The D and E rings are difficult to see from Earth under particularly favorable conditions; rings F and G are discovered for the first time. The order of designation of the rings is due to historical reasons, so it does not coincide with the alphabetical one. If we arrange the rings as they move away from Saturn, then we get a series: D, C, B, A, F, G, E. Of particular interest and great discussion was the F ring.
Unfortunately, it has not yet been possible to make a final judgment about this object, since the observations of the two Voyagers do not agree with each other. The onboard cameras of Voyager 1 showed that the F ring consists of several rings with a total width of 60 km, with two of them intertwined with each other like a string. For some time, the prevailing opinion was that two small, newly discovered satellites moving directly near the F ring, one from the inner edge, the other at the outer one (slightly slower than the first, since it is farther from the planet), are responsible for this unusual configuration.
The attraction of these satellites does not allow the extreme particles to go far from its middle, that is, the satellites, as it were, "graze" the particles, for which they received the name "shepherds". They, as shown by calculations, cause the movement of particles along a wavy line, which creates the observed interweaving of the ring components. But Voyager 2, which passed near Saturn nine months later, did not find any interweaving or any other shape distortions in the F ring - in particular, in the immediate vicinity of the "shepherds". Thus, the shape of the ring turned out to be variable. Of course, two observations are not enough to judge the causes and regularities of this variability. It is impossible to observe the F ring from the Earth with modern means - its brightness is too low.
The D ring is the closest to the planet. Apparently, it extends to the most cloudy ball of Saturn. Ring E is the outermost. Extremely rarefied, it is at the same time the widest of all - about 90 thousand km. The size of the zone it occupies is from 3.5 to 5 radii of the planet. The density of matter in the E ring increases towards the orbit of Saturn's moon Enceladus. Perhaps Enceladus is the source of the substance of this ring. The particles of the rings are probably icy, covered with frost on top. This was already known from ground-based observations, and onboard spacecraft instruments only confirmed the correctness of this conclusion.
Particle sizes of the main rings have been estimated from ground-based observations to range from centimeters to meters. As Voyager 1 passed near Saturn, the spacecraft's radio transmitter successively pierced the A ring, the Cassini fission, and the C ring with a 3.6 cm radio beam.
Then the radio emission was received on Earth and analyzed. It was possible to find out that the particles of these zones scatter radio waves mainly forward, although in somewhat different ways. Thanks to this, the average diameter of the particles of ring A was estimated at 10 m, Cassini fission - at 8 m and ring C - at 2 m. Strong forward scattering, but already in visible light, was found in the rings F and E. fine dust (the diameter of a grain of dust is about ten-thousandths of a mm)
In ring B, a new structural element was found - radial formations, called "spokes" because of their external resemblance to the spokes of a wheel. They also consist of fine dust and are located above the plane of the ring. It is possible that the "spokes" are held there by the forces of electrostatic repulsion. It is curious to note that images of "spokes" were found on some sketches of the planet Saturn, made in the last century. But then no one gave them any importance. Exploring the rings, the Voyagers discovered an unexpected effect - numerous short-term bursts of radio emission coming from the rings. This is nothing more than signals from electrostatic discharges - a kind of lightning.
The source of the electrification of the particles, apparently, is the collision between them. In addition, a gaseous atmosphere of neutral atomic hydrogen enveloping the rings was discovered. The Voyagers observed the Laysan-alpha line (1216 A) in the ultraviolet part of the spectrum. According to its intensity, the number of hydrogen atoms in a cubic centimeter of the atmosphere was estimated. There were about 600 of them. I must say, some scientists, long before the launch of spacecraft to Saturn, predicted the possibility of the existence of an atmosphere near the rings. Voyagers also attempted to measure the mass of the rings. The difficulty was that the mass of the rings is at least a million times less than the mass of the planet Saturn. The mass of the rings is obviously less than 1.7 millionths of the mass of the planet.
| D ring | 67 000 - 74 500 | 7 500 | |
| Ring C | 74 500 - 92 000 | 17 500 | |
| Coulomb gap | 77 800 | 100 | Charles Coulomb??? |
| Maxwell slit | 87 500 | 270 | James Clerk Maxwell |
| Ring B | 92 000 - 117 500 | 25 500 | |
| Division of Cassini | 117 500 - 122 200 | 4 700 | Giovanni Cassini |
| Huygens gap | 117680 | 285 - 440 | Christian Huygens |
| Ring A | 122 200 - 136 800 | 14 600 | |
| Enkle division | 133 570 | 325 | Johann Enkle |
| Keeler's slit | 136 530 | 35 | James Keeler |
| E/2004 S 1 | 137 630 | ? | |
| E/2004 S2 | 138 900 | ? | |
| F ring | 140 210 | 30 - 500 | |
| G ring | 165 800 - 173 800 | 8 000 | |
| E ring | 180 000 - 480 000 | 300 000 |
Discovery of the fine structure of rings
The most "original" of the planets, the planet Saturn, just like Mars, is under close attention of the astronomical population of the Earth.
XVII CENTURY: "I see the ring clearly"
The unusual appearance of the planet Saturn was first noticed by Galileo Galilei in the summer of 1610. He “with great surprise observed Saturn not in the form of one star, but consisting of three fixed almost touching stars, while the central one is larger than the side ones and all three are located in a straight line ... They are not visible through a tube with a lower magnification as three separate stars: the planet Saturn is represented by an elongated star in the shape of an olive." Galileo compared the side stars to obedient servants who help the aged Saturn to make his way and always keep on either side of him. Soon, however, nature played a trick on the researcher. In 1612, the ring of Saturn turned out to be an edge turned to the Earth and the "obedient servants" disappeared from the field of view of the Galilean tube.
In 1614, the "lateral stars" of Saturn were seen in his pipe by the Jesuit Christopher Scheiner, in 1616 by Galileo himself, and in the 30s and 50s of the 17th century they were noticed by such famous observers as Pierre Gassendi, Francesco Fontana, Giovanni-Batista Riccioli , Jan Hevelius. But although individual sketches of the planet definitely showed ring outlines, they could not unravel the mystery of the unearthly diva. Even Hevelius, who discovered the periodicity of the change in the phases of the visibility of Saturn, did not manage to figure out what these decorations of Saturn are. The correct explanation of the "curiosity" of the planet and the periodic changes in its appearance was given in 1659 by Christian Huygens, who had been observing the planet Saturn since 1655, first in a 12-foot, and then in a new 23-foot telescope; "girded with a ring, thin, flat, not adjoining anywhere, inclined to the ecliptic."
Foreseeing "the incredulity of those who consider it unusual and wrong" that he "attributes to a celestial body a form hitherto not seen, while it is considered an immutable law of nature that they should be spherical," Huygens emphasized: "I did not invent this assumption thanks to my imagination and imagination... but I clearly see the ring with my own eyes."
1 - G. Galilei, 1610; 2 - K. Scheiner, 1614; 3 - P. Gassendi, 1633; 4 - G. Riccioli, 1640; 5, 6, 7, 8 - J. Hevelius, 1640- 1650; 9, 10 - P. Gassendi, 1645; 11 - E. Divini, 1647; 12 - F. Fontana, 1648; 13, 14, 15 - G. Riccioli, 1648-1650; 16, 17 - X. Huygens, 1656, 1659;18 - J. Campani, 1664;19 - V. Ball, 1665;20 - J. Hevelius, 1675;21 - J. Cassini, 1676
In 1664, Giuseppe Campani, one of the recognized masters of telescope construction, checking the quality of his 35-foot instrument, "split" the ring of Saturn into two - outer, darker, and inner, light (rings A and B according to the modern designation introduced in the 19th century O. V. Struve). And in 1675, Christian Huygens and Jean-Dominique Cassini discovered a dark band between these two rings. It was later called the Cassini division. Thus, the "classical" (that is, reflected in the school textbook of astronomy) features of the ring of Saturn were established in the 17th century.
XVIII CENTURY: confusion and vacillation
We first meet with correct ideas about the structure of the ring of the planet Saturn in one of the works of Jacques Cassini (1715). In his opinion, the ring could be "a cluster of satellites that were in the same plane and revolved around the planet; ... their size is so small that they cannot be seen separately, but at the same time they are so close to each other, that it is impossible to distinguish the gaps between them, therefore it seems as if they form a single continuous body. Cassini argued this version by referring to Kepler's third law, according to which a solid ring must be destroyed by the planet's gravity.
True, there are good reasons to believe that such an explanation of the nature of the Saturn ring belongs to another French scientist, Personier Roberval, one of the founders of the Paris Academy in 1666. However, this hypothesis was purely speculative, and therefore far from the only one. In the 30s of the XVIII century, the French scientist and engineer P.-L. Maupertuis suggested that Saturn's ring owes its origin to comets captured by the planet during a close passage. The heads of the comets became satellites of Saturn, and the tails formed rings. J.-J. Meran and J.-L. Buffon, Maupertuis's colleagues at the Paris Academy, considered the ring to be a remnant of the planet's equatorial substance. According to Maran, the planet Saturn originally had a large size, but, shrinking as a result of cooling, threw off the outer layers; according to Buffon, the ring separated from the planet due to an excess of centrifugal force. For the first time, the dark inner ring of Saturn (Ring C) was observed by the English astronomer Thomas Wright.
The ring of Saturn seemed to him "formed of many rings, of which two are very clearly visible and the third is noticeable. I observed them with a reflector with a 5-foot focus in March, 1739, and the outer was related to the inner (ring A to ring B), as 1 to 3, and the rest (ring C) seemed very dark. At that time, the ring was maximally deployed, "An interesting hypothesis on the structure of the ring of Saturn was developed in 1755 by Immanuel Kant in his work" General Natural History and Theory of the Sky ". He was already aware of the observation of "many concentric rings separated from each other by some space." Assuming the ring to be a "gas of particles".
Kant argued that since the balance of the ring is due to the equality of gravity and centrifugal force, then, in accordance with the law of conservation of angular momentum, a rarefied, but still "collisional" disk will be split into narrow concentric bands and this will prevent the ring from complete destruction. Kant's reasoning about the dynamics of a rarefied ring is quite consistent, and the conclusion about the fragmentation of the ring into concentric zones anticipated the stunning discoveries of the 19th and 20th centuries. So, the classical results of the 17th century were overgrown with motley reports of the observation of various bands on the A and B rings.
XIX CENTURY: And yet it is crushed!
The most curious details of the structure of the ring of Saturn were revealed to the English captain Henry Keiter - an optician, surveyor, metrologist. On December 17, 1825, observing through a Newtonian telescope (40" focus, 6.25" aperture), Keiter suggested that he saw "the outer ring divided by numerous dark bands, extremely close, one being stronger than the others and dividing the ring roughly in half." The same evening the phenomenon was witnessed by two other people to whom Cater showed the ring of Saturn. On January 16 and 17, 1826, the stripes seemed less distinct to Cater.
Finally, on January 22, 1828, when the main division was perfectly traced, "no trace of the divisions of the outer ring was felt. Therefore, I am convinced that they are not unchanged." Cater reported his observations in early 1826 to John Herschel, who soon examined the ring of Saturn with a 20-foot telescope and found nothing special. In the summer of 1826, Vasily Yakovlevich Struve, based on his observations, stated: "As for the division of the ring into numerous parts, I did not notice any traces."
However, in 1838, the Roman priest Francesco de Vico again clearly saw in a 6-inch achromatic telescope and showed his students and friends three dark bands - one almost in the middle of ring A and two others on ring B. The visibility of the bands varied slightly depending on atmospheric conditions, and when Saturn passed through the meridian, six rings were sometimes seen at once. In the same year, a detailed article by the German astronomer Johann Franz Encke was published. He wrote that on April 25, 1837, when the literature on the divisions of the ring of Saturn was almost unknown to him, he tested a new achromatic eyepiece and saw that the "ears" of the outer ring were divided by strokes into two equal parts. The fission was systematically studied in May-July, a number of micrometric measurements of its position and thickness were made.
The appearance of this low-contrast band, which Encke and others simultaneously observed either in the middle of ring A or a little closer to its outer edge, is due, as it turned out today, to the superposition of several nearby dark bands.
At the same time, modern observations have confirmed the presence of an extremely narrow high-contrast slit near the outer edge of the A ring, which was clearly seen in the 36-inch refractor of the Lick Observatory (USA) and sketched by James Keeler on January 7, 1888. But it is this band that is now called the Encke division. In his article, Encke also cited observational data by Johann Gottfri de Galle, who saw that on May 8, 1838 "" the inner edge of the inner ring blurred", and on May 25 "the dark space between Saturn and its ring was formed, up to the middle, by a smooth stretching the inner edge of the ring into darkness."
This timid description of the C ring is given "100 years after Wright's observations. Wright's results never became known to the general astronomical public; on the contrary, Halle's observations, published in the Proceedings of the Berlin Academy of Sciences, became known "only" 13 years later, shortly after after the C ring was finally discovered in America and Europe at the end of 1850. In the fall of 1851, independently, on different continents, divisions on the B ring were again registered. be a single system, solid or liquid, and confirmed - at a higher mathematical level - Kant's conclusion about the fragmentation of the ring.For a system of rings to exist, it, Maxwell argued, "must consist of an infinite number of independent particles circulating around the planet at different speeds.
These particles can be collected in a series of narrow rings, or they can move randomly within their ensemble. In the first case, the destruction will be extremely slow, in the second - faster, but at the same time there may be a tendency to cluster into narrow rings, which will slow down the destructive action. : independence from the place of observation and specific instruments, repeatability, possibility of verification. But why, after all, since the middle of the 19th century, no one has observed numerous divisions on the rings A and B? Perhaps this is partly due to the deterioration of the astroclimate - astronomers were the first to feel the consequences global industrial boom.
The history of visual observations of the ring of Saturn, its fine structure over the past hundred years has almost been forgotten, but today - thanks to the "instructions" of the Voyagers - has been hastily restored, and interest in it has revived again. And then we learned that the discovery of a large number of divisions on the ring of the planet Saturn would not have been a curiosity for astronomers of the 19th century.
It is amazing how much the alleged fragmentation of the ring in the drawings of the English astronomer R. Proctor coincides with the image transmitted to Earth by Voyager 1. Recognizing the merits of past astronomers in the study of "Saturn's decoration", the International Astronomical Union recently assigned the names of Huygens, Maxwell and Keeler to individual divisions of the ring.
satellites
If before the flights of spacecraft to Saturn, 10 satellites of the planet were known, now we know about 60 natural satellites of Saturn, as well as three supposed ones. The largest of the moons is Titan. Scientists suggest that the conditions on this satellite of Saturn are similar to those that existed on our planet 4 billion years ago, when life was just emerging on Earth.
The new moons are quite small, but nonetheless, some of them have a serious impact on the dynamics of the Saturn system. Such, for example, is a small satellite moving at the outer edge of the ring A, it does not allow the particles of the ring to go beyond this edge - this is Atlas.
Some of them have an average density of 1.0 g/cm3, which is more in line with water ice. The density of others is somewhat higher, but also small (an exception is Titanium). For example, Rhea, the fifth classical moon of Saturn, has a density of 1.3 g/cm3. The presence of a large amount of ice in the satellites of Saturn is a direct indication of their formation in the zone of low temperatures, which are still characteristic of the outer part of the solar system. According to existing theories, during the formation of planets at the periphery of the protoplanetary cloud, temperatures were very low, and light volatile substances, such as water vapor, condensed mainly at the periphery.
The satellites are named after the heroes of ancient myths about titans and giants. Almost all of these cosmic bodies are light. The largest satellites form an inner rocky core.
The planet's moons and its rings offer several mysteries to celestial mechanics. In 1980, several groups of researchers announced amazing new discoveries. For example, in the orbit of Dione, the fourth large satellite, another satellite S6 (Helena) is moving.
Below are listed all the satellites of the planet Saturn, which have their own names, in order of their distance from the planet, indicating in brackets their radii (in kilometers) and average distances from Saturn (in thousands of kilometers):
| Pan | 10 | 133,583 |
| Daphnis | 7 | 136,505 |
| Atlas | 20 | 137,7 |
| Pandora | 70 | 139,4 |
| Prometheus | 55 | 141,7 |
| Epimetheus | 70 | 151,4 |
| Janus | 110 | 151,5 |
| Mimas | 196 | 185,5 |
| Meton | 1,5 | 194,3 |
| Pallena | 2 | 212,3 |
| Enceladus | 250 | 238 |
| Tethys | 530 | 294,66 |
| Telesto | 17 | 294,66 |
| Calypso | 17 | 294,66 |
| Dione | 560 | 377,39 |
| Elena (Helena, Dione B) | 18 | 377,39 |
| Polydeuces | 1,8 | 377,39 |
| Rhea | 754 | 527,1 |
| Titanium | 2575 | 1221,9 |
| Hyperion | 205 | 1481 |
| Iapetus | 730 | 3560,8 |
| Kiviok | 8 | 11333,2 |
| Ijirak | 6 | 11372,8 |
| Phoebe | 110 | 12944 |
| Paliak | 9,7 | 14923,8 |
| Skadi | 3,2 | 15576,2 |
| Albiorix | 16 | 16401,6 |
| Erriapo | 4,3 | 17408,7 |
| Ciarnak | 20 | 17905,7 |
| Tarvos | 6,5 | 18160,2 |
| Mundilfari | 2,8 | 18360,1 |
| Narvi | 3,3 | 19370,7 |
| Suttung | 2,8 | 19666,7 |
| Hold (Thrymr) | 2,8 | 20810,3 |
| And peace | 8 | 23174,6 |
All open satellites are relatively small in size, have a geometric albedo of 0.3-0.5 and are irregular, with one exception, in shape. Among them, the so-called “shepherd” satellites were first discovered (sometimes, by analogy with the English term, they are called “guard dogs”). With their gravitational influence, they seem to focus the movement of individual particles in rings, preventing them from falling out of the general ensemble.
The orbits of small satellites with these features are arranged as follows. At the outermost edge of the A ring, at an average distance from the center of Saturn of 137,670 km, is the “shepherd” of the A ring, 1980 S 28 (Atlas), about 20 km in size. 1980 S 27 and 1980 S 26 are, respectively, the inner and outer "shepherds" of the F ring with dimensions of 70x40 and 55x40 km and an average radius of orbits of 139353 and 141700 km. Two co-orbital satellites, 1980 S 1 and 1980 S 3 (Janus and Epimetheus), slightly larger: 110x90 km and 70x55 km. Their orbits differ by only 50 km: 151422 and 151472 km. In the orbit of Tethys (294700 km) there are small bodies 50-60 km in size, 1980 S 25 and 1980 S 13 (Calypso and Telesto), the first of which may have a more or less regular spherical shape. Finally, in the orbit of Dione (377,500 km) is the same small body - 1980 S 6.
Let's move on to the classical (large) satellites of Saturn. All of them (except Phoebe) are in synchronous rotation, that is, they are constantly facing Saturn on one side (Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, Phoebe).
Tracking the moons of Saturn:
In these five pairs of photographs taken by the Space Telescope. Hubble, it is noticeable how some of Saturn's moons move around their ringed planet. All images were taken sequentially, with an interval of 97 minutes (this is the period of revolution of the telescope around the Earth) on November 21, 1995. The photographs were taken by the 2nd wide-angle planetary camera. Usually the bright rings of Saturn are visible almost from the end. The large, bright moon of Dione hangs in the center of the top pair of photos, while the smaller moons Pandora, Prometheus, and Mimas (top right) are near the planet's disk near the outer ring.
In the second and third pair of pictures, the satellites Rhea and Epimetheus fly by as if in a dance. When the rings of Saturn are located end to Earth, the amount of light coming from the rings is reduced. Then astronomers are given the opportunity to explore the complex system of satellites of this planet and look for hardly noticed undiscovered satellites.
Discovery history
The planet Saturn is one of the five planets in the solar system that are easily visible to the naked eye from Earth. At its maximum, the brightness of Saturn exceeds the first magnitude.
For the first time observing the planet Saturn through a telescope in 1609-1610, Galileo Galilei noticed that Saturn does not look like a single celestial body, but like three bodies that almost touch each other, and suggested that these are two large "companions" (satellites) of Saturn . Two years later, Galileo repeated his observations and, to his amazement, found no satellites.
In 1659, Huygens, using a more powerful telescope, found out that the "companions" are actually a thin flat ring encircling the planet and not touching it. Huygens also discovered Saturn's largest moon, Titan. Since 1675, Cassini has been studying the planet. He noticed that the ring consists of two rings separated by a clearly visible gap - the Cassini gap, and discovered several more large satellites of Saturn.
In 1979, the Pioneer 11 spacecraft first flew near Saturn, followed by Voyager 1 and Voyager 2 in 1980 and 1981. These devices were the first to detect the magnetic field of Saturn and explore its magnetosphere, observe storms in the atmosphere of Saturn, take detailed pictures of the structure of the rings and find out their composition.
In the 1990s, the planet Saturn, its moons and rings were repeatedly studied by the Hubble Space Telescope. Long-term observations have provided a lot of new information that was not available to Pioneer 11 and Voyagers during their single flyby of the planet.
In 1997, the Cassini-Huygens spacecraft was launched to Saturn and, after seven years of flight, on July 1, 2004, it reached the Saturn system and went into orbit around the planet. The main objectives of this mission, designed for at least 4 years, is to study the structure and dynamics of the rings and satellites, as well as to study the dynamics of the atmosphere and magnetosphere of Saturn. In addition, a special probe "Huygens" separated from the apparatus and parachuted down to the surface of Saturn's moon Titan.
| Year | Scientist | Opening |
| 1610 | G. Galileo | First telescopic observation of Saturn. Drawn as three stars. |
| 1633 | The first sketch of the planet Saturn. | |
| 1655 | G.H. Huygens | March 25 opens the ring of Saturn and the first satellite - Titan. |
| 1671 | J. Cassini | The satellite Iapetus opens, 12/23/1672 - the satellite of Rhea, 1675 - the target in the ring, in 1684 the satellites of Tethys and Dione. |
| 1790 | W. Herschel | Determines the rotation period of Saturn. |
| 1837 | I. F. Enke | Opens a second gap in the ring. |
| 1838 | I. G. Galle | Opens the inner ring of Saturn (ring C in ring B). |
| 1840 | J. F. Herschel | Gives a name to the first five discovered satellites. |
| 1857 | D. C. Maxwell | He proved theoretically that rings should consist of many unbound particles (the work was published in 1859). |
| 1876 | The White Spot opens (observed periodically). | |
| 1895 | A.A. Belopolsky | Proves the meteor composition of Saturn's rings. |
| 1932 | Methane and ammonia have been discovered in the planet's atmosphere. | |
| 1979 | Spacecraft "Pioneer - 11" | Flying on September 1 at 21,400 km from the planet, he discovered the planet's magnetosphere and showed the fine structure of the rings. Two new rings have been opened. |
| 1980 | Spacecraft "Voyager - 1" | November 12 flies past the planet at 123,000 km, explores the Titan satellite, discovers 5 satellites, new rings. |
| 1981 | Spacecraft "Voyager - 2" | On August 27, it approaches the planet. Explores Titan, radiation belts, magnetic field. |
| 2000 | Brett Gladman | During the year, it opens 10 new satellites around the planet. |
Saturn compared to Earth
| main parameters | Saturn indicator | Earth indicator | Saturn/Earth |
| MAIN PARAMETERS OF THE PLANET | |||
| Weight (1024 kg) | 568,46 | 5,9736 | 95,159 |
| Volume (1010 km3) | 82713 | 108,321 | 763,59 |
| Equatorial radius (km) | 60268 | 6378,1 | 9,449 |
| Polar radius (km) | 54364 | 6356,8 | 8,552 |
| Volumetric mean radius (km) | 58232 | 6371,0 | 9,140 |
| Average density (kg/m3) | 687 | 5515 | 0,125 |
| Gravity (m/s2) | 10,44 | 9,80 | 1,065 |
| Free fall acceleration (m/s2) | 8,96 | 9,78 | 0,916 |
| Second escape velocity (km/s) | 35,5 | 11,19 | 3,172 |
| Albedo | 0,342 | 0,306 | 1,12 |
| visual albedo | 0,47 | 0,367 | 1,28 |
| Solar energy (W/m2) | 14,90 | 1367,6 | 0,011 |
| Black body temperature (K) | 81,1 | 254,3 | 0,319 |
| Moment of inertia (I/MR2) | 0,210 | 0,3308 | 0,635 |
| Number of natural satellites | 47 | 1 | - |
| planetary ring system | Yes | Not | - |
| MAIN PARAMETERS OF THE ORBIT | |||
| Semi-major axis (distance from the Sun) (106 km) | 1433,53 | 149,60 | 9,582 |
| Sidereal orbital period (days) | 10759,22 | 365,256 | 29,457 |
| Tropical orbit period (days) | 10746,94 | 365,242 | 29,424 |
| Maximum orbital speed (km/s) | 10,18 | 30,29 | 0,336 |
| Minimum orbital speed (km/s) | 9,09 | 29,29 | 0,310 |
| Orbital inclination (degrees) | 2,485 | 0,000 | - |
| Orbit Eccentricity | 0,0565 | 0,0167 | 3,383 |
| Period of rotation around its axis (hours) | 10,656 | 23,9345 | 0,445 |
| Daylight hours (hours) | 10,656 | 24,0000 | 0,4414 |
| Axis tilt (degrees) | 26,73 | 23,45 | 1,140 |
| MAIN OBSERVATORY PARAMETERS | |||
| Researcher | unknown | ||
| opening date | prehistoric times | ||
| Minimum distance to Earth (106 km) | 1195,5 | ||
| Maximum distance to Earth (106 km) | 1658,5 | ||
| Maximum visual magnitude | 0,43 | ||
| MAIN PARAMETERS OF THE ATMOSPHERE | |||
| Surface pressure (bar) | over 1000 bars | ||
| Atmospheric density 1 bar (kg/m3) | 0,19 | ||
| Atmospheric altitude (km) | 59.5 | ||
| Wed temperature 1 bar (K) | 134 K / - 139 C | ||
| Wed temperature 0.1 bar (K) | 84 K / - 189 C | ||
| Wind speed (m/s) | 400 m/s (30° latitude) | ||
| Molecular weight | 2.07 g/mol | ||
| The main composition of the atmosphere | Molecular hydrogen (H2) - 96.3%; Helium (He) - 3.25% | ||
| Other constituents - ppm (ppm) | Methane (CH4) - 4500 (2000); Ammonia (NH3) - 125 (75); HD - 110 (58); Ethane (C2H6) - 7 (1.5); | ||
| Aerosols | Ammonia and water ice crystals, ammonia hydrosulfide | ||
Saturn- a planet of the solar system with rings: size, mass, orbit, composition, surface, satellites, atmosphere, temperature, research by devices with photos.
Saturn is the sixth planet from the Sun and perhaps the most beautiful object in the solar system.
This is the most distant planet from a star that can be found without the use of instruments. So its existence has been known for a long time. Before you is one of the four gas giants, located 6th in order from the Sun. You will be curious to know what planet Saturn is, but first, get acquainted with interesting facts about the planet Saturn.
Interesting facts about the planet Saturn
Can be found without tools
- Saturn is the 5th brightest planet in the solar system, so you can see it with binoculars or a telescope.
He was seen by ancient people
- The Babylonians and the inhabitants of the far east watched him. Named after the Roman Titan (similar to the Greek Kronos).
The flattest planet
- The polar diameter covers 90% of the equatorial one, which is based on a low density index and rapid rotation. The planet performs an axial rotation every 10 hours and 34 minutes.
A year is 29.4 years long
- The ancient Assyrians, because of the slowness, nicknamed the planet "Lubadshagush" - "the oldest of the oldest."
There are bands in the upper atmosphere
- The composition of the upper layers of the atmosphere is represented by ammonia ice. Below them are water clouds, and then there are cold mixtures of hydrogen and sulfur.
There are oval storms
- The area above the north pole took on a hexagonal shape (hexagon). Researchers believe that this may be a wave pattern in the upper clouds. There is also a vortex over the south pole that resembles a hurricane.
The planet is represented mainly by hydrogen
- The planet is divided into layers that penetrate Saturn more densely. At great depths, hydrogen becomes metallic. At the heart of the hot interior.
Endowed with the most beautiful ring system
- The rings of Saturn are made of ice fragments and a small admixture of carbonaceous dust. They stretch for 120,700 km, but are incredibly thin - 20 m.
The lunar family includes 62 satellites
- Saturn's moons are icy worlds. The largest are Titan and Rhea. Enceladus may have a subsurface ocean.
Titan has a complex nitrogen atmosphere
- Consists of ice and stone. The frozen surface layer is endowed with lakes of liquid methane and landscapes covered with frozen nitrogen. Can have life.
Sent 4 missions
- These are Pioneer 11, Voyager 1 and 2 and Cassini-Huygens.
Size, mass and orbit of the planet Saturn
The average radius of Saturn is 58232 km (equatorial - 60268 km, and polar - 54364 km), which is 9.13 times larger than the earth's. With a mass of 5.6846 × 10 26 kg and a surface area of 4.27 × 10 10 km 2 , its volume reaches 8.2713 × 10 14 km 3 .
| polar contraction | 0.097 96 ± 0.000 18 |
|---|---|
| Equatorial | 60,268 ± 4 km |
| Polar radius | 54 36 ± 10 km |
| Surface area | 4.27 10 10 km² |
| Volume | 8.27 10 14 km³ |
| Weight | 5.68 10 26 kg 95 terrestrial |
| Average density | 0.687 g/cm³ |
| Acceleration free fall at the equator |
10.44 m/s² |
| Second space velocity | 35.5 km/s |
| equatorial speed rotation |
9.87 km/s |
| Rotation period | 10h 34min 13s ± 2s |
| Axis Tilt | 26.73° |
| declination of the north pole | 83.537° |
| Albedo | 0.342 (Bond) |
| Apparent magnitude | from +1.47 to -0.24 |
| Absolute stellar magnitude |
0,3 |
| Angular diameter | 9% |
The distance from the Sun to the planet Saturn is 1.4 billion km. At the same time, the maximum distance reaches 1,513,783 km, and the minimum - 1,353,600 km.
The average orbital speed reaches 9.69 km / s, and Saturn spends 10759 days to pass around the star. It turns out that one year on Saturn lasts 29.5 Earth years. But here the situation with Jupiter is repeated, where the rotation of the regions occurs at different speeds. The shape of Saturn resembles an oblate spheroid.
The composition and surface of the planet Saturn
You already know which planet Saturn is. It is a gas giant represented by hydrogen and gas. The average density of 0.687 g / cm 3 is surprising. That is, if you place Saturn in a huge reservoir, the planet will remain afloat. It has no surface, but has a dense core. The fact is that heating, density and pressure increase with the proximity to the core. The structure is explained in detail in the bottom photo of Saturn.
Scientists believe that Saturn resembles Jupiter in structure: a rocky core around which hydrogen and helium are concentrated with a small admixture of volatile substances. The composition of the core may resemble that of the Earth, but with an increased density due to the presence of metallic hydrogen.
Inside the planet, the temperature rises to 11,700°C, and the amount of energy radiated is 2.5 times what it receives from the Sun. In a sense, this is due to the slow gravitational contraction of the Kelvin-Helmholtz. Or it's all about rising droplets of helium from the depths into the hydrogen layer. In this case, heat is released and helium is taken away from the outer layers.
Calculations in 2004 say that the core should be 9-22 times larger than the earth's mass, and the diameter should be 25,000 km. It is surrounded by a dense layer of liquid metallic hydrogen followed by helium-saturated molecular hydrogen. The outermost layer extends for 1000 km and is represented by gas.
Satellites of the planet Saturn
Saturn boasts 150 moons, of which only 53 have official names. Among them, in 34, the diameter does not reach 10 km, and 14 - from 10 to 50 km. But some inner satellites extend 250-5000 km.
Most of the satellites were named after the titans from the myths of ancient Greece. The innermost moons are endowed with slight orbital inclinations. But irregular satellites in the most separated areas are located millions of kilometers and can make a round in several years.
The interior includes Mimas, Enceladus, Tethys and Dione. They are represented by water ice and may have a rocky core, icy mantle and crust. The smallest is Mimas with a diameter of 396 km and a mass of 0.4 x 10 20 kg. The shape resembles an egg, it is 185.539 km away from the planet, which is why it takes 0.9 days to orbit the passage.
Enceladus with indicators of 504 km and 1.1 x 10 20 kg has a spherical speed. It takes 1.4 days to pass around the planet. It is one of the smallest spherical moons, but is endogenously and geologically active. This caused the appearance of parallel faults at the southern polar latitudes.
Large geysers were noticed in the south polar area. These jets serve as a source for replenishing the E ring. They are important because they can hint at the presence of life on Enceladus, because the water comes from the underground ocean. The albedo is 140%, so it is one of the brightest objects in the system. Below you can admire the photo of the satellites of Saturn.
With a diameter of 1066 km, Tethys is the second largest moon of Saturn. Most of the surface is represented by craters and hills, as well as a small number of plains. Distinguished crater Odysseus, stretching for 400 km. There is also a system of canyons that deepens by 3-5 km, stretches for 2000 km, and is 100 km wide.
The largest inner moon is Dione - 1112 km and 11 x 10 20 kg. Its surface is not only ancient, but also heavily damaged by impacts. Some craters reach a diameter of 250 km. There is also evidence of geological activity in the past.
The outer satellites are located outside the E-ring and are represented by water ice and rock. This is Rhea with a diameter of 1527 km and a mass of 23 x 10 20 kg. It is 527.108 km away from Saturn, and spends 4.5 days on an orbital passage. The surface is also littered with craters and several large faults are visible on the rear hemisphere. There are two large impact basins with a diameter of 400-500 km.
Titan extends for 5150 km, and its mass is 1.350 x 10 20 kg (96% of the mass of the orbit), which is why it is considered the largest satellite of Saturn. It is the only large moon with its own atmospheric layer. It is cold, dense, and holds nitrogen and methane. There are small amounts of hydrocarbons and ice crystals of methane.
The surface is difficult to see due to the dense atmospheric haze. Only a few crater formations, cryo-volcanoes and longitudinal dunes are visible. This is the only body in the system with methane-ethane lakes. Titan is 1,221,870 km away and is believed to have an underground ocean. It takes 16 days to go around the planet.
Hyperion lives near Titan. With a diameter of 270 km, it is inferior in size and mass to Mimas. This is an egg-shaped brown object that, due to the crater surface (2-10 km in diameter), resembles a sponge. There is no predictable rotation.
Iapetus extends for 1470 km, and in terms of mass it occupies 1.8 x 10 20 kg. This is the most distant moon, located at 3,560,820 km, which is why it takes 79 days to pass. It has an interesting composition because one side is dark and the other is lighter. Because of this, they are called yin and yang.
The Inuit include 5 moons named after Inuit mythology: Ijirak, Kiviok, Paliak, Ciarnak and Tarkek. Their prograde orbits range from 11.1-17.9 million km, and their diameter is 7-40 km. Orbital inclinations are 45-50°.
Gallic family - outer satellites: Albiorix, Befin, Erripo and Tarvos. Their orbits are 16-19 million km, the inclination is from 35° to -40°, the diameter is 6-32 km, and the eccentricity is 0.53.
There is a Scandinavian group - 29 retrograde moons. Their diameter is 6-18 km, distance is 12-24 million km, inclination is 136-175°, and eccentricity is 0.13-0.77. Sometimes they are called the Thebes family in honor of the largest satellite, stretching for 240 km. Then follows Ymir - 18 km.
Between the inner and outer moons lives a group of Alcoinids: Methon, Anfa and Pallene. They are the smallest moons of Saturn. Some large moons have their own small ones. So Tethys has Telesto and Calypso, and Dion has Helena and Polydeuces.
Atmosphere and temperature of the planet Saturn
Saturn's outer atmosphere is 96.3% molecular hydrogen and 3.25% helium. There are also heavier elements, but there is little information about their proportions. Propane, ammonia, methane, acetylene, ethane and phosphine were found in small quantities. The upper cloud cover is represented by ammonia crystals, and the lower cloud cover is represented by ammonium hydrosulfide or water. UV rays lead to metaline photolysis, which causes chemical reactions of the hydrocarbon.
The atmosphere looks striated, but the lines weaken and widen towards the equator. There is a division into upper and lower layers, differing in composition based on pressure and depth. The upper ones are represented by ammonia ice, where the pressure is 0.5–2 bar and the temperature is 100–160 K.
At a pressure level of 2.5 bar, a line of ice clouds begins, which stretches to 9.5 bar, and heating is 185-270 K. Here, ammonium hydrosulfide bands mix at a pressure of 3-6 bar and a temperature of 290-235 K. The lower layer is represented by ammonia in an aqueous solution with indicators of 10-20 bar and 270-330 K.
Sometimes long-period ovals form in the atmosphere. The most famous is the Great White Spot. Created every Saturnian year at the summer solstice in the northern hemisphere.
Spots wide can stretch for several thousand km and were noted in 1876, 1903, 1933, 1960 and 1990. Since 2010, the "northern electrostatic disturbance" noticed by Cassini has been monitored. If these clouds adhere to periodicity, then next time we will note the appearance in 2020.
In terms of wind speed, the planet is in second place after Neptune. Voyager recorded an indicator of 500 m / s. A hexagonal wave is noticeable at the north pole, and a massive jet stream is visible at the south pole.
For the first time, the hexagon was seen in the photographs of Voyager. Its sides extend for 13,800 km (larger than Earth's diameter), and the structure rotates in 10 hours, 39 minutes and 24 seconds. The south pole vortex was observed with the Hubble telescope. There is a wind with an acceleration of 550 km / h, and the storm is similar in size to our planet.
Rings of the planet Saturn
It is believed that these are old rings and could have formed along with the planet. There are two theories. One says that earlier the rings were a satellite that collapsed due to a close approach to the planet. Or the rings were never part of the satellite, but are a remnant of the nebular material from which Saturn itself emerged.
They are divided into 7 rings, between which a gap is established. A and B are the densest and cover 14,600 and 25,300 km in diameter. They extend 92000-117580 km (B) and 122170-136775 km (A) from the center. The Cassini Division occupies 4,700 km.
C is separated from B by 64 km. It occupies a width of 17,500 km, and is removed from the planet by 74,658-92,000 km. Together with A and B, it contains the main rings with larger particles. Next come dusty rings, because they have small particles.
D occupies 7500 km and extends inward for 66900-75510 km. At the other end are G (9000 km and a distance of 166,000-175,000 km) and E (300,000 km and a distance of 166,000-480,000 km). F is located on the outer edge of A and is harder to classify. Mostly it's dust. It covers 30-500 km in width and extends for 140-180 km from the center.
History of the study of the planet Saturn
Saturn can be found without the use of telescopes, so it was seen by ancient people. Mentions are found in legends and mythology. The earliest records belong to Babylon, where the planet was recorded with reference to the sign of the zodiac.
The ancient Greeks called this giant Kronos, who was the god of agriculture and was the youngest of the titans. Ptolemy was able to calculate the orbital passage of Saturn when the planet was in opposition. In Rome, they used the Greek tradition and gave today's name.
In ancient Hebrew, the planet was called Shabbatai, and in the Ottoman Empire, Zuhal. Hindus have Shani, who judges everyone, evaluating good and bad deeds. The Chinese and Japanese called it the earth star, considering it one of the elements.
But the planet was observed only in 1610, when Galileo saw it through his telescope and the rings were discovered. But the scientist thought that these were two satellites. Only Christian Huygens corrected the mistake. He also found Titan, and Giovanni Cassini found Iapetus, Rhea, Tethys and Dione.
The next important step was taken by William Herschel in 1789, when he found Mimas and Enceladus. And in 1848, Hyperion appears.
Drawing of Saturn by Robert Hooke (1666)
Phoebus was found in 1899 by William Pickering, who guessed that the satellite has an irregular orbit and rotates synchronously with the planet. In the 20th century, it became clear that Titan had a thick atmosphere that had not been seen before. The planet Saturn is an interesting object for research. On our website you can study his photo, watch a video about the planet and learn many more interesting facts. Below is a map of Saturn.
Click on the image to enlarge it
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0.47 (geom.albedo)
| Surface temperature | min | Wednesdays | Max |
|---|---|---|---|
| level 1 bar | 134K | ||
| 0.1 bar | 84K |
| ~96 % | Hydrogen (H 2) |
| ~3 % | Helium |
| ~0,4 % | Methane |
| ~0,01 % | Ammonia |
| ~0,01 % | Hydrogen deuteride (HD) |
| 0,000 7 % | Ethane |
| Ice: | |
| Ammonia | |
| Water | |
| Ammonium hydrosulfide (NH 4 SH) |
Saturn has a prominent ring system made up mostly of ice particles with a smaller amount of rock and dust. There are currently 62 known satellites revolving around the planet. Titan is the largest of them, as well as the second largest satellite in the solar system (after Jupiter's satellite, Ganymede), which is larger than the planet Mercury and has the only dense atmosphere among the many satellites of the solar system.
physical characteristics
Orbital characteristics
The average distance between Saturn and the Sun is 1,433,531,000 kilometers (9.58 AU). Moving at an average speed of 9.69 km / s, Saturn revolves around the Sun in 10,759 days (approximately 29.5 years). Saturn and Jupiter are in an almost exact 2:5 resonance. Since the eccentricity of Saturn's orbit is 0.056, the difference between the distance to the Sun at perihelion and aphelion is 162 million kilometers.
General information
Atmosphere
Saturn's upper atmosphere is 93% hydrogen (by volume) and 7% helium (compared to 18% in Jupiter's atmosphere). There are impurities of methane, water vapor, ammonia and some other gases. Ammonia clouds in the upper part of the atmosphere are more powerful than those of Jupiter.
Saturn exploration
Saturn is one of the five planets in the solar system that are easily visible to the naked eye from Earth. At its maximum, the brightness of Saturn exceeds the first magnitude.
View of Saturn through a modern telescope (left) and through a telescope from the time of Galileo (right)
Observing Saturn for the first time through a telescope in -1610, Galileo Galilei noticed that Saturn does not look like a single celestial body, but like three bodies almost touching each other, and suggested that these are two large
Comparison of Saturn and Earth
"companion" (satellite) of Saturn. Two years later, Galileo repeated his observations and, to his amazement, found no satellites.
satellites
As of February 2010, 62 moons of Saturn are known. 12 of them were discovered using spacecraft: Voyager 1 (1980), Voyager 2 (1981), Cassini (2004-2007). Most satellites, except for Hyperion and Phoebe, have a synchronous rotation of their own - they are always turned to Saturn on one side. There is no information about the rotation of the smallest moons.
During 2006, a team of scientists led by David Jewitt of the University of Hawaii, working on the Japanese Subaru Telescope in Hawaii, announced the discovery of 9 moons of Saturn.
All of them belong to the so-called irregular satellites, which are distinguished by their elongated elliptical orbits, and are believed not to have formed along with the planets, but were captured by their gravitational field.
In total, since 2004, Jewitt's team has discovered 21 moons of Saturn.
The largest of the moons is Titan. Scientists suggest that the conditions on this satellite are similar to those that existed on our planet 4 billion years ago, when life was just emerging on Earth.
Rings
Today it is known that all four gaseous giants have rings, but Saturn has the most beautiful and noticeable. The rings are at an angle of approximately 28° to the plane of the ecliptic. Therefore, from the Earth, depending on the relative position of the planets, they look different: they can be seen both in the form of rings and “from the edge”.
As Huygens suggested, the rings are not a solid solid body, but consist of billions of tiny particles in orbit around the planet.
There are three main rings and the fourth is thinner. Together they reflect more light than the disk of Saturn itself. The three main rings are usually denoted by the first letters of the Latin alphabet. Ring B is the central one, the widest and brightest, it is separated from the larger outer ring A by the Cassini gap, almost 4000 km wide, in which there are the thinnest, almost transparent rings. Inside ring A there is a thin gap called Encke's dividing strip. Ring C, which is even closer to the planet than B, is almost transparent.
The rings of Saturn are very thin. With a diameter of about 250,000 km, their thickness does not reach even a kilometer (although there are also peculiar mountains on the surface of the rings). Despite its impressive appearance, the amount of substance that makes up the rings is extremely small. If it were assembled into one monolith, its diameter would not exceed 100 km.
Probe images show that the rings are actually made up of thousands of rings interspersed with slits; the picture resembles the tracks of gramophone records. The particles that make up the rings are mostly a few centimeters in size, but occasionally there are bodies several meters in size. Very rarely - up to 1-2 km. The particles appear to be composed almost entirely of ice or rocky matter covered in ice.
There is complete consistency between the rings and satellites of the planet. Indeed, some of them, the so-called "shepherd satellites", play a role in keeping the rings in their places. Mimas, for example, is "responsible" for the absence of matter in the Cassini gap, while Pan is located inside the Encke dividing strip.
The origin of Saturn's rings is not yet entirely clear. Perhaps they formed at the same time as the planet. However, this is an unstable system, and the material they are composed of is periodically replaced, probably due to the destruction of some of the small moons.
- There is no solid surface on Saturn. The average density of the planet is the lowest in the solar system. The planet is made up primarily of hydrogen and helium, the 2 lightest elements in space. The density of the planet is only 0.69 that of water. This means that if there were an ocean of the appropriate size, Saturn would float on its surface.
- The robotic Cassini spacecraft, currently (October 2008) orbiting Saturn, has transmitted images of the planet's northern hemisphere. Since 2004, when Cassini flew up to her, there have been noticeable changes, and now it is painted in unusual colors. The reasons for this are not yet clear. Although it is not yet known why Saturn's coloration evolved, it is assumed that the recent color change is related to the changing seasons.
Hexagonal atmospheric formation at Saturn's north pole
- Clouds on Saturn form a hexagon - a giant hexagon. This was first discovered during Voyager's flybys of Saturn in the 1980s, a phenomenon that has never been observed anywhere else in the solar system. If Saturn's south pole, with its spinning hurricane, doesn't seem odd, then the north pole might be a lot more unusual. The strange structure of the clouds is shown in an infrared image taken by the Saturn-orbiting Cassini spacecraft in October 2006. The images show that the hexagon has remained stable for 20 years since Voyager's flight. Films showing Saturn's north pole show that the clouds retain their hexagonal pattern as they rotate. Individual clouds on Earth may be shaped like a hexagon, but unlike them, the cloud system on Saturn has six well-defined sides of almost equal length. Four Earths can fit inside this hexagon. There is no complete explanation for this phenomenon yet.
Aurora over Saturn's north pole
- On November 12, 2008, the cameras of the robotic Cassini spacecraft took infrared images of Saturn's north pole. In these frames, the researchers found auroras, which have never been observed before in the solar system. In the image, these unique auroras are colored blue, while the clouds below are colored red. The image shows a previously discovered hexagonal cloud just below the auroras. Auroras on Saturn can cover the entire pole, whereas on Earth and Jupiter, aurora rings, being magnetically driven, only surround the magnetic poles. On Saturn, the usual ring auroras were also observed. Recently photographed unusual auroras over Saturn's north pole have changed significantly over the course of a few minutes. The changing nature of these auroras indicates that the variable flow of charged particles from the Sun is subject to the action of some kind of magnetic forces that were not previously suspected.
Notes
see also
Links
- Saturn's moons have rings, just like the planet itself
- Photos of Saturn taken by the Cassini probe from 2004 to 2009.
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