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Saturn's rings are at present 90 to 95 percent water ice. Because dust and debris from rocky meteoroids have polluted the rings, the rings are believed to have consisted of pure ice when they formed. This composition is unusual compared to the approximately half-ice and half-rock mixture expected for materials in the outer Solar System. Similarly, the low densities of Saturn's inner moons show that they too are, as a group, unusually rich in ice.
The previous leading ring origin theory suggests the rings formed when a small satellite was disrupted by an impacting comet. "This scenario would have likely resulted in rings that were a mixture of rock and ice, rather than the ice-rich rings we see today," says the paper's author, Dr. Robin M. Canup, associate vice president of the SwRI Planetary Science Directorate in Boulder.
A moon about the size of Titan — Saturn's largest satellite — likely spiraled into the giant planet about 4.5 billion years ago, scientists think. As it made its way, Saturn's powerful gravity stripped off the doomed moon's icy outer layers, thus spawning the planet's magnificent rings, according to the research.
A Titan-size satellite would fling off enough icy bits to make a ring system initially 10 to 100 times more massive than the one we see today. But these rings would shrink over time, according to the theory. Ice particles would collide and move about, with some spreading inward to get gobbled up by Saturn.
Other ice pieces would spread outward, where they'd start to stick together. Eventually, enough would coalesce to form icy moons such as Tethys, Enceladus and Mimas — whose masses are consistent with what the model predicts.
In addition to explaining the odd iciness of Saturn's rings and inner satellites, Canup said, the model also has the advantage of describing events that are a natural part of a giant planet's formation and youth.
The theory will be put to the test in 2017, when NASA’s Cassini mission finishes its grand tour of Saturn by making the best measurements yet of the mass of the rings. Researchers can use those and other details to better tease out how the rings evolved over time.
More in the linked below articles, and numbers & maths in Supplementary Information PDF document.
Links:
The previous leading ring origin theory suggests the rings formed when a small satellite was disrupted by an impacting comet. "This scenario would have likely resulted in rings that were a mixture of rock and ice, rather than the ice-rich rings we see today," says the paper's author, Dr. Robin M. Canup, associate vice president of the SwRI Planetary Science Directorate in Boulder.
A moon about the size of Titan — Saturn's largest satellite — likely spiraled into the giant planet about 4.5 billion years ago, scientists think. As it made its way, Saturn's powerful gravity stripped off the doomed moon's icy outer layers, thus spawning the planet's magnificent rings, according to the research.
A Titan-size satellite would fling off enough icy bits to make a ring system initially 10 to 100 times more massive than the one we see today. But these rings would shrink over time, according to the theory. Ice particles would collide and move about, with some spreading inward to get gobbled up by Saturn.
Other ice pieces would spread outward, where they'd start to stick together. Eventually, enough would coalesce to form icy moons such as Tethys, Enceladus and Mimas — whose masses are consistent with what the model predicts.
In addition to explaining the odd iciness of Saturn's rings and inner satellites, Canup said, the model also has the advantage of describing events that are a natural part of a giant planet's formation and youth.
The theory will be put to the test in 2017, when NASA’s Cassini mission finishes its grand tour of Saturn by making the best measurements yet of the mass of the rings. Researchers can use those and other details to better tease out how the rings evolved over time.
More in the linked below articles, and numbers & maths in Supplementary Information PDF document.
Links:
- Nature:
- Discovery News: Saturn's Rings: Robbed From a Moon?
- SPACE.com: Saturn's Rings May Be Remains of Ripped-Apart Moon.
- EurekAlert: Demise of large satellite may have led to the formation of Saturn's rings and inner moons.
- ScienceNews: Saturn’s rings explained.
- Science: Violent Origin for Saturn's Rings.
- msnbc: Saturn's rings: Leftovers from a cosmic murder?
- ABC Science: New theory for Saturn's rings.
Supplementary Information
