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Saturn: Rings
The rings of Saturn have puzzled astronomers since Galileo Galilei discovered them with his telescope in 1610. Detailed study by the Voyager 1 and Voyager 2 spacecraft in the 1980s only increased the mystery.
There are thousands of rings made of up billions of particles of ice and rock. The particles range in size from a grain of sugar to the size of a house. The rings are believe to be pieces of comets, asteroids or shattered moons that broke up before they reached the planet. Each ring orbits at a different speed around the planet. Information from NASA's Cassini mission will help reveal how they formed, how they maintain their orbit and, above all, why they are there in the first place.
While the other three gas planets in the solar system - Jupiter, Uranus and Neptune - have rings orbiting around them, Saturn's are by far the largest and most spectacular. With a thickness of about 1 kilometer (3,200 feet) or less, they span up to 282,000 km (175,000 miles), about three quarters of the distance between the Earth and its moon.
Named alphabetically in the order they were discovered, the rings are relatively close to each other, with the exception of the Cassini Division, a gap measuring 4,700 kilometers (2,920 miles). The main rings are, working outward from the planet, known as C, B, and A. The Cassini Division is the largest gap in the rings and separates Rings B and A. In addition a number of fainter rings have been discovered more recently. The D Ring is exceedingly faint and closest to the planet. The F Ring is a narrow feature just outside the A Ring. Beyond that are two far fainter rings named G and E. The rings show a tremendous amount of structure on all scales; some of this structure is related to gravitational perturbations by Saturn's many moons, but much of it remains unexplained.
To enter Saturn's orbit, Cassini flew through the gap between the F and the G rings, farther from the planet than the Cassini Division. As a safe measure, during the crossing of the ring plane, instruments and cameras onboard the spacecraft were shut off temporarily. However, the spectacular crossing into Saturn's orbit brought incredible information, images and footage, while the instruments onboard are still collecting unique data that may answer many questions about the rings' composition.
Reference: USGS Astrogeology: Gazetteer of Planetary Nomenclature - Ring Nomenclature
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Ring Name: D
Distance*: 66,970 - 74,490 km Width: 7,500 km
Ring Name: C
Distance*: 74,490 - 91,980 km Width: 17,500 km
Ring Name: Columbo Gap
Distance*: 77,800 km Width: 100 km
Ring Name: Maxwell Gap
Distance*: 87,500 km Width: 270 km
Ring Name: Bond Gap
Distance*: 88,690 - 88,720 km Width: 30 km
Ring Name: Dawes Gap
Distance*: 90,200 - 90,220 km Width: 20 km
Ring Name: B
Distance*: 91,980 - 117,580 km Width: 25,500 km
Ring Name: Cassini Division
Distance*: 117,500 - 122,050 km Width: 4,700 km
Ring Name: Huygens gap
Distance*: 117,680 km Width: 285 km - 440 km
Ring Name: Herschel Gap
Distance*: 118,183 - 118,285 km Width: 102 km
Ring Name: Russell Gap
Distance*: 118,597 - 118,630 km Width: 33 km
Ring Name: Jeffreys Gap
Distance*: 118,931 - 118,969 km Width: 38 km
Ring Name: Kuiper Gap
Distance*: 119,403 -119,406 km Width: 3 km
Ring Name: Leplace Gap
Distance*: 119,848 - 120,086 km Width: 238 km
Ring Name: Bessel Gap
Distance*: 120,305 - 120,318 km Width: 10 km
Ring Name: Barnard Gap
Distance*: 120,305 - 120,318 km Width: 13 km
Ring Name: A
Distance*: 122,050 - 136,770 km Width: 14,600 km
Ring Name: Encke Gap
Distance*: 133,570 km Width: 325 km
Ring Name: Keeler Gap
Distance*: 136,530 km Width: 35 km
Ring Name: Roche Division
Distance*: 136,770 - 139,380 km Width: 2600 km
Ring Name: F
Distance*: 140,224 km Width: 30 km - 500 km
Ring Name: G
Distance*: 166,000 - 174,000 km Width: 8,000 km
Ring Name: E
Distance*: 180,000 - 480,000 km Width: 300,000 km
* The distance is measured from the planet center to the start of the ring.
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