Saturn's rings may be youngWhen the Voyager spacecraft swept past Saturn, they radioed back photos of a complex, very dynamic system of rings -- thousands of rings. Studies of these rings have led some astronomers to wonder if they are really as old as Saturn itself. Two lines of thinking suggest a recent origin:
by William R. Corliss
May-Jun 1985
(1) The rings are composed of both light material (very likely water ice) and dark material (probably rocks and dust). The rocky fragments, according to the prevailing nebular theory, should have condensed early in solar-system history, and then been swept gravitationally into the planet as they were slowed by friction with the uncondensed nebular material. Yet, dark material is still in the rings. (2) The incessant bombardment of the rings by meteorites should have pulverized the rings, sending fragments and vaporized material in all directions. In just 10 million years the rings should have been largely erased. They are still there.
(Cuzzi, Jeffrey N.; "Ringed Planets: Still Mysterious -- II," Sky and Telescope, 69:19, 1985.)Saturn's Rings: FormationThe prevailing theory as to how Saturn's rings were formed comes from the 19th century astronomer Édouard Roche. Roche predicted that if an object such as a moon were to come too close to a large planet such as Saturn, eventually it would be torn apart by tidal forces - the uneven gravitational pull upon an object due to its size.
Adler Planetarium
Under a tidal force, an object experiences a greater gravitational pull on its nearer side than its farther side. If the difference in force is great enough, this can cause a strain which literally breaks an object apart. Scientists now call this limit where an object will be torn apart by tidal forces the Roche Limit.