Saturn+Diagrams

In 1610 Galileo Galilei turned his primitive telescope to the heavens and was astonished to observe a bright star flanked by two dimmer ones. What Galileo had discovered was a strange new world, a planet that was to become one of the wonders of the solar system, and to be named Saturn. Saturn's beauty comes from its magnificent rings that Galileo described as "handles" or large moons on either side of the planet. He said, "I have observed the highest planet [[|Saturn]] to be tripled-bodied. This is to say that to my very great amazement Saturn was seen to me to be not a single star, but three together, which almost touch each other". Two years later Galileo was puzzled to discovered the rings had disappeared. What Galileo did not know was that the Earth had passed through Saturn's ring plane and the rings were edge on and could not be resolved with his 20x telescope. Galileo's discovery of Saturn commenced the scientific process of unraveling the mysteries of Saturn's extensive ring system, but even after 400 years the mysteries have not been all solved.

Hubble Space Telescope Image of Saturn's rings edge on. [[|more]] In 1655 Christann Huyges proposed that Saturn was surrounded by a solid ring, "a thin, flat ring, nowhere touching, and inclined to the ecliptic." As time went on, more and more observations were made and theories proposed. It took until the mid 1800s before the notion that the ring was made out of small particles rather than being solid became the prominent theory. In 1979 [|Pioneer 11] became the first spacecraft to fly past Saturn and take pictures of the planet and rings. Although the pictures are of low resolution by today's standards, they were better than any previous photos taken through telescopes. In 1980 and 1981 [|Voyager 1 and Voyager 2] flew past the planet and took numerous high-resolution images of Saturn and its rings. The next major milestone will be in 2004 when the [|Cassini] spacecraft arrives at Saturn. Cassini will be the first spacecraft to go into orbit about the planet. Here it will operate studying Saturn, its moons, rings and environment for the next four years. 

Ring Structure
Saturn's ring system is divided up into 7 major divisions with alphabetic designators in the order of discovery. From the innermost ring to the outermost ring the designators are D, C, B, A, F, G and E. Each major division is further subdivided into thousands of individual ringlets. The F and G rings are very thin and difficult to see while the A, B, and C rings are broad and quite visible. Between the A and B rings is a gap called the Cassini division named after Giovanni Cassini who discovered the Gap in 1676. Between the A and F rings lies the Keeler (Encke) gap. Much of the elaborate structure of the rings is due to gravitational effects of nearby satellites. This phenomenon is demonstrated by the relationship between the F-ring and two small moons [|Prometheus] and [|Pandora] that shepherd the ring material. The F-ring shows a complex structure made up of two narrow, braided, bright rings along which "knots" are visible. Scientists speculate that the knots may be clumps of ring material, or mini moons. In the mid 1980s Dr. Jeff Cuzzi noticed a wavy pattern in the ring material on both sides of the Encke gap. It was suggested that an unseen asteroid-sized moon in the gap caused the disturbance. Dr. Mark Showalter further analyzed the disturbance and used this "moonlet wake" pattern that resembled a motorboat wake, to determine the position and mass of the unseen body. The amplitude of the waves, he said suggested the mass of the unobserved object and the wavelength of the ripples revealed the moon's possible position. Using this mathematical model, Dr. Showalter was able to predict which Voyager images the moon would be in. In 1990 Dr. Showalter's work paid off and [|Pan] was discovered within the Encke gap.  (km) ||  ||~ Width (km) ||  ||~ Thickness (km) ||  ||~ Optical Depth ||  ||~ Mass (g) ||  ||~ Albedo ||
 * Saturn's braided F-Ring. [[|more]] ||
 * Saturn's braided F-Ring. [[|more]] ||
 * ~ Name ||  ||~ Distance*


 * ~ D ||  || 66,000 - 73,150 ||   || 7,150 ||   || ? ||   || 0.01 ||   || ? ||   || ? ||


 * ~ C ||  || 74,500 - 92,000 ||   || 17,500 ||   || ? ||   || 0.05 - 0.35 ||   || 1.1 x 1024 ||   || 0.12 - 0.30 ||


 * ~ Maxwell Gap ||  || 87,500 ||   || 270 ||   ||   ||   ||   ||   ||   ||   ||   ||


 * ~ B ||  || 92,000 - 117,500 ||   || 25,500 ||   || 0.1 - 1 ||   || 0.8 - 2.5 ||   || 2.8 x 1025 ||   || 0.5 - 0.6 ||


 * ~ Cassini Div ||  || 117,500 - 122,200 ||   || 4,700 ||   || ? ||   || 0.05-0.15 ||   || 5.7 x 1023 ||   || 0.2 - 0.4 ||


 * ~ A ||  || 122,200 - 136,800 ||   || 14,600 ||   || 0.1 - 1 ||   || 0.4-0.5 ||   || 6.2 x 1024 ||   || 0.4 - 0.6 ||


 * ~ Encke gap ||  || 133,570 ||   || 325 ||   ||   ||   ||   ||   ||   ||   ||   ||


 * ~ Keeler gap ||  || 136,530 ||   || 35 ||   ||   ||   ||   ||   ||   ||   ||   ||


 * ~ F ||  || 140,210 ||   || 30 - 500 ||   || ? ||   || 0.01-1 ||   || ? ||   || 0.6 ||


 * ~ G ||  || 164,000 - 172,000 ||   || 8,000 ||   || 100 - 1000 ||   || 10-6 ||   || 1020 ||   || ? ||


 * ~ E ||  || 180,000 - 480,000 ||   || 300,000 ||   || 1,000 ||   || 10-5 ||   || ? ||   || ? ||


 * The distance is measured from the planet center to the start of the ring.