No. 39: May-Jun 1985
When 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:
(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.)
Comment. Assuming the rings are young, where did they come from? What happened to Saturn in "recent" times?
Reference. Several lines of evidence point to the youth of Saturn's rings. See: ARL16 in our catalog The Moon and the Planets. Ordering information here.
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