United States. National Aeronautics and Space Administration

“ Outbound and above the ring plane, Voyager 1 gave us this view of Saturn’s rings eight hours after its closest approach to the planet. The unique lighting accentuates the many hundreds of bright and dark ringlets comprising the ring system. The C-Ring (dark gray area) seems to blend into the brighter B-Ring as the concentric features radiate out from the planet. The dark spoke-like features seen in images taken during the approach to Saturn now appear as bright streaks, indicating that they may be composed of small particles. ”

“ Although it is only about one-third the size of Jupiter’s magnetosphere, Saturn’s magnetosphere is still an enormous structure, extending nearly two million kilometers from the planet toward the Sun. The size of the magnetosphere fluctuates rhythmically as the flow of charged particles in the solar wind increases or decreases in intensity. The magnetosphere can be pushed inside Titan’s orbit, so that at times the satellite finds itself outside of the magnetosphere altogether. ”

“ Only once every 175 years are the outer planets aligned in their orbits so that we can take advantage of gravity-assist trajectories to achieve encounters with Jupiter, Saturn, Uranus, and Neptune on one mission. The gravity-assist technique uses one planet’s gravity field and motion through space to alter the spacecraft’s flight path and propel it outward toward the next planet. ”

“ As Voyager 1 approached Saturn, a series of dark and light cloud bands (belts and zones) became apparent in the planet’s northern hemisphere through a high altitude atmospheric haze. The planet’s shadow obscures the rings behind and immediately to the east of the disk. In addition, the shadow of the rings on the planet’s disk can be seen just north of the rings themselves as they cross in front of the planet. Six of Saturn’s 15 known satellites are visible. Saturn’s largest moon, Titan (considerably larger than Earth’s moon) , is clearly visible in the upper left corner. ”

“ Mimas, Saturn’s innermost large satellite, has an impact crater covering more than one quarter the diameter of the entire moon. Nowhere else in the solar system has such a disproportionately large feature been seen. In fact, it is believed that any impact larger than this would probably have shattered Mimas into two or more fragments. The crater has a raised rim and central peak, typical of large impact structures on terrestrial planets. Additional smaller craters, 15 to 45 kilometers (10 to 30 miles) in diameter, can be seen scattered across the surface, particularly along the terminator. ”

“ Wind speeds up to 1500 kilometers per hour (900 miles per hour) occur at the equator—four to five times faster than any Jovian winds. Temperatures near the cloudtops range from 86 to 92 kelvins (-305° to -294° Fahrenheit) —nearly 60 degrees colder than at Jupiter. Saturn still radiates about 2.8 times as much heat as it receives from the Sun. The coolest temperatures are found at the center of the equatorial zone.
Auroral emissions have been seen near Saturn’s poles, and auroral-type emissions have been seen in ultraviolet light near the illuminated limb of the planet. ”

“ These charged particles whiz by Titan at a dizzying rate of more than 200 kilometers (120 miles) per second. Titan leaves a motorboat-like wake in its orbital path.
Extending from the orbit of Titan inward to the orbit of Rhea, an enormous cloud of uncharged hydrogen atoms forms a doughnut-shaped torus of ultraviolet-emitting particles. Because of their neutrality, these atoms are not towed around by Saturn’s magnetic field.
Close to the planet, Saturn’s rings act as an effective shield or absorber of charged particles. ”

“ Titan is a large, bizarre satellite. It is larger (almost 5120 kilometers or 3180 miles in diameter) than the planet Mercury and possesses a dense atmosphere of unique composition. Voyager 1’s cameras show Titan’s surface to be totally obscured by a thick layer of atmospheric haze. ”

“ Mimas displays an impact crater whose diameter is one-fourth that of the satellite—such an impact must have nearly shattered the icy satellite. Tethys has a valley 70 kilometers (40 miles) wide that stretches 800 kilometers (500 miles) across the satellite, an 39 apparent crustal fracture resulting from seismic activity. Several sinuous valleys, some of which appear to branch, are visible on Dione’s surface. Both Dione and Rhea have bright, wispy streaks on their already highly reflective surfaces, perhaps caused by ice thrown out of craters by meteorite impacts. ”

“ The spacecraft are both complex—automatically responding to their Earth-bound monitors that remotely control them via radio commands—and highly autonomous—capable of caring for themselves in many areas through a system of sensors, computers, and spare equipment. Each spacecraft functions on about 400 watts of electrical power which is provided by nuclear generators. Broadcasts of data across a billion miles to Earth are accomplished with a spacecraft transmitter power of only about 25 watts, the amount of energy required by a small household light bulb. ”

“ The “gap” in the ring (left center) is not real but is the location of a reseau mark on the camera’s vidicon tube. These bright features in the F-Ring appear to move at the orbital rate of the ring particles and may be larger bodies or thicknesses in the rings. Saturn’s thirteenth and fourteenth satellites, which orbit on either side of the F-Ring, may act like “sheepdogs,” herding the F-Ring particles between them. Less than 100 kilometers (60 miles) wide, the F-Ring is located outside of the A-Ring. Satellite 14, discovered by Voyager 1, is seen just inside the F-Ring. ”

“ In this photograph, the shadow of the satellite Dione is seen as a dark circle on the face of the planet.
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11/10/80 3.5 million km (2.2 million mi)
A ribbon-like wave structure and small convective features marking a westward jet stream above the wave are visible in this photograph of Saturn’s cloudtops. The view, extending from 40 degrees to 60 degrees north latitude, shows features 65 kilometers (40 miles) in diameter. Measurements in images such as this one indicate that Saturn has fewer east-to-west wind currents than does Jupiter. ”

“ The B-Ring appears dark from below the ring plane because it is dense enough to reflect most of the sunlight, causing it to appear very bright when seen from the sunward side. The opaline brightness of the Cassini Division here indicates a great deal of sunlight being scattered through this region. ”

“ The haze layers merge into a darkened hood over the north pole. At the poles, liquid nitrogen lakes may form. The surface temperature is probably near 100 kelvins (-280° Fahrenheit) , only slightly warmer than the boiling point of liquid nitrogen. ”