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Nothing but the facts about Saturn's rings

written by: ebishirl•edited by: RC Davison•updated: 1/7/2013

Saturn is not the only ringed planet in the solar system -- Jupiter, Uranus and Neptune also have rings -- but it does by far display the most fascinating and complex system of rings anywhere in our planetary neighborhood.

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    The Facts

    Saturn Rings from Cassini 1) Year discovered: 1610

    2) Discovered by: Galileo Galilei (though he couldn't identify them as rings)

    3) Year idenfitied as rings: 1655

    4) Identified as rings by: Christiaan Huygens

    5) First extensively photographed by: Pioneer 11 (1979) took the first low-resolution photos, but the planet was much more extensively photographed by Voyager 1 (1980) and Voyager 2 (1981).

    6) Distance of rings from Saturn's center: 66,000 to 480,000 km (that's 41,010 to 298,258 miles)

    7) Thickness: No more than 1000 km or 621 feet

    8) Size of particles in rings: anywhere from 1 cm to several meters, with some larger objects and "moonlets"

    9) Composition of particles in rings: Make up of mainly water ice with trace amounts of silicate materials.

    10) Estimated total mass of rings: Possibly more than three times that of Saturn's moon Mimas (which is 3.75 x 10^19 kg or 8.27 x 10^19 lbs)

    11) Types of rings: The main rings (A, B and C), the dusty rings (D, E and G), F Ring

    12) How rings were named: In the order of discovery (i.e., "A" was discovered first)

    13) Innermost ring: D Ring (67,000 to 74,500 km, or 41,632 to 46,292 miles, from Saturn's center)

    14) Outermost ring: E Ring (180,000 to 480,000 km, or 111,847 to 298,258 miles, from Saturn's center)

    15) Leading theory for ring formation: Breakup of a moon (either through tidal forces or meteor impact), leftover remnants from the early solar system

    16) Likely source of material in E Ring: Microscopic, cryovolcanic material from the moon Enceladus

    17) Age of rings: Uncertain (theories range from 100 million years to 4 billion years old, though recent data from Cassini-Huygens indicate the older age is more likely)

    18) Other ring features: "Braided" rings, ringlets, spokes (radial features)

    19) Likely cause of spokes: Saturn's magnetic field

    20) Largest gap in rings: Cassini Division (4,700 km, or 2,920 miles, wide)

    21) Likely causes of gaps in rings: Gravitational pull of "shepherd" moons, resonance effects between ring particles and moons

    Saturn Rings Closeup Above left: A natural-color mosaic image of Saturn's rings, taken by Cassini. (Image credit: NASA/JPL/Space Science Institute,

    Right: A closeup of Saturn's A Ring. (Image credit: NASA/JPL/Space Science Institute,

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    More Amazing Facts About Saturn's Rings

    Saturn Rings Spokes 1) The rings have their own atmosphere. Flying close by the rings, Cassini-Huygens observed enhanced levels of oxygen gas in the ring system. Researchers believe water from the rings is broken up into its components, hydrogen and oxygen; the hydrogen dissipates while the oxygen stays.

    2) Saturn's A Ring acts like a giant sponge. In addition to feeding material into the E Ring, cryovolcanoes on the moon Enceladus are also spewing out gases that become plasma that's sucked into the A Ring.

    3) What a disappearing act. As Saturn circles the sun (once every 29.5 years), the angle at which we view its rings changes. Twice during each circuit, the rings are edge-on as viewed from Earth, making them all but disappear. These ring plane crossings vexed Galileo ("Has Saturn swallowed his children?" he asked during a ring plane crossing in 1612), but they're a great time for astronomers to study Saturn for new moons and other features without the glare from the rings.

    Saturn Rings and Moon Waves Above left: Cassini's image of radial spokes in Saturn's B Ring. (Image credit: NASA/JPL/Space Science Institute,

    Right: Cassini helps find a new moon, the seven-km-wide S/2005 S1, in the Keeler gap of Saturn's rings. (Image credit: NASA/JPL/Space Science Institute,

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