Information about Saturn has been obtained by both ground-based and American space probes, of which there were already four: three fly-by-wire probes, Pioneer-Saturn (alias Pioneer-11, 1979), Voyager-1 (1980) and Voyager-2 (1981); and one orbital, Cassini-Huygens (NASA/ESA/ISA), which reached the Saturn system in the summer of 2004. The most significant results were obtained by Voyagers and Cassini.
Saturn could be a large planet, solely slightly smaller than Jupiter and really similar in size. The quantity of Saturn is 800 times the quantity of the world. The rotation amount within the latitude vary regarding 40° is ten hours thirty-nine.4 minutes. It's smaller within the equatorial zone (10 60 minutes twelve min), whereas within the polar regions, above 57˚, it exceeds eleven 60 minutes. Fast rotation results in a powerful contraction of the planet: the polar radius to equatorial quantitative relation is zero.9. The equatorial diameter is one hundred twenty 540 kilometers on the higher boundary of the cloud layer. The typical density of Saturn is never low — below the density of water.
The main adornment of Saturn is its rings: outer A, middle B, and inner C. Galileo first noticed them in 1610. But because of the imperfection of his telescope, he could not recognize the ring and decided that he saw satellites. The honor of discovering Saturn's rings belongs to Huygens. This happened 46 years after Galileo's observations, in 1656.
Although Saturn is very far from Earth, it is one of the most beautiful objects in the sky, even when observing with a telescope of moderate size. Like Jupiter, Saturn has a developed system of belts and zones. However, they are never as clearly visible as the stripes on Jupiter. If we add to this the double distance of Saturn, the difficulty of exploring the planet from Earth becomes apparent. And yet astronomers have sometimes been able to trace the movement of some low-contrast spots, which allowed to find zonal periods of rotation of Saturn. But from a board of a space probe, it is visible much more details. "Voyagers-1 and -2" passed by Saturn in 1980-81 with an interval of nine months, which allowed to trace the change of details on the planet's disk. The surface of the cloud layer, which differed poorly in 1980, became quite clear the following year. The decisive role in this could be played by the change of seasons on Saturn, where spring in the northern hemisphere began. Since the equator tilts to the orbit plane at Saturn at 29 degrees, the change of seasons there should result in greater solar heat influxes in each of the hemispheres than on Earth. It was possible to distinguish between cyclonic formations in different parts of the planet at a distance of six weeks on the Voyager-2 images. Sequential images helped to trace in detail the development of cyclones.
By analogy with the Jupiter's massive Red Spot, one among the large oval formations found on Saturn was referred to as the massive Brown Spot (BKP). The meteorology of Saturn and Jupiter isn't similar in everything. Not like Jupiter's atmosphere details, that don't rise on top of 60° latitudes, Saturn's belts and zones reach terribly high latitudes. The Saturn OPF lies simply sixteen degrees from the North Pole. Not like Jupiter, the part currents, whose movement is noticeable against the background of the cloudy layer and is most frequently directed to the east, square measure determined at terribly high latitudes, up to 78˚. The speed of such flows reaches 600 m/s. Next to them one will see brown spots — hurricanes, and therefore the largest of them in diameter reach half the world. The speed at the edge of hurricanes is comparatively low, concerning thirty m/s. As a result of the considerably higher rate than on Jupiter, these hurricanes quickly change state, growing into flows and exchanging energy with them.
A small inflow of solar heat could not provide the active dynamics of Saturn's atmosphere. As in Jupiter, the formation of eddies is determined by energy sources buried deep in the atmosphere. Detailed images of temperate latitudes show a greater number of local hurricanes with vortex diameters of 1000 km and more. The speed of zonal winds on Saturn is very high. In the region of the equator, it reaches 400-500 m/s, which is 4 times higher than at Jupiter. However, at latitudes 30˚ and above the speed is less, have a periodic latitudinal character and do not exceed 100 m/s. Apparently, the lifetime of large eddies in the Saturn atmosphere is short compared to that of Jupiter, as strong winds destroy eddies. According to Voyager data, the latitudinal distribution of winds in the southern hemisphere mirrors this distribution in the northern hemisphere. Nevertheless, the difference in the atmospheric dynamics of the two hemispheres becomes noticeable in their polar regions.
An extended cloudy layer and rapidly growing deep atmospheric density significantly weaken sunlight.
At a depth of 350 km below the surface of the clouds, it can be dark. The actual illumination depends on the light scattering characteristics of the Saturn atmosphere. Since the structure and composition of the cloud layer of Jupiter and Saturn are assumed to be similar, the lower boundary is within the same temperature range of about 150 K. But because of the four times smaller amount of heat produced per unit area, the upper boundary of the Saturn cloud layer does not coincide with its position at Jupiter. Unlike Jupiter, the spectral bands of ammonia in Saturn are weak. This is connected with low temperatures in the supra cloud atmosphere, where the ammonia vapor freezes out. The rather dense fog layer formed here hides the structure of belts and zones, which is so well visible on Jupiter.
The tails of neutral and ionized gas molecules and atoms, which form gigantic toruses in orbits, stretch beyond Saturn's satellites. One of these toruses is connected with the atmosphere of Titan - the largest satellite of Saturn and the second in size and mass among the satellites of the planets (in the first place is the satellite of Jupiter Ganymede, and they are larger than Mercury!).
The surface of Titan, which has a diameter of 5152 km, is indistinguishable through the dense atmosphere, which has a pressure at the surface of 1.5 bars and consists of 98.4% nitrogen and 1.6% methane. It also contains small amounts of ethane, propane, acetylene, argon, carbon monoxide and carbon dioxide, helium and other gases. The temperature of the upper atmosphere of Titan is close to -120˚C and the surface temperature is -179˚C. The fog in the atmosphere scatters and reflects the sun's rays, creating an "anti-greenhouse effect" that reduces the surface temperature. In the daytime, the surface is not brighter than at dusk on Earth. The surface of Titan consists of ice with an admixture of silicate rocks. The average satellite density is 1.88 g/cm³. Titan has no magnetic field. The gravity there is 7 times weaker than the Earth's so that given the high air density, a man on Titan would probably be able to fly by fortifying his wings.
The measured brightness temperature of the outer layer of clouds on Saturn was only 80-90K, and the effective temperature of the planet was 95K. The solar energy density reaching Saturn looks very small, almost 10 times smaller than our small Earth. Against this background, one can see one's own energy sources:? Heat flux from Saturn, according to various estimates, is 1.9-2.2 times greater than the flow of energy received from the Sun. This is partly a relics heat, but not only it.
Gravitational differentiation is called as an additional source of energy. One of the most realistic hypotheses is that heavier helium slowly sinks into the center of the planet and hydrogen floats up; this movement produces heat that is eventually emitted into space. This hypothesis is confirmed by the fact that the Saturn atmosphere contains 94% hydrogen (by volume) and helium is almost all the other 6%. If the composition of both planets is the same, this difference may indeed indicate that a significant proportion of helium on Saturn has "drowned".