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You'd think for all their
fame the rings of Saturn would be well understood. Not so.
The rings are made rock
and dust and ice in varying sizes. Astronomers used to suppose it was all leftovers
of planet formation 4.5 billion years ago. Now
they think perhaps the rings are the result of a more recent catastrophe
-- an event just hundreds of millions of years ago. Perhaps a Moon-sized object
flew by the planet and was torn apart. Or maybe an asteroid slammed into an
existing Saturnian moon.
Saturn's ring system is a about 155,000 miles
(250,000 km) wide but in places only a few hundred feet thick.
The planet Uranus has
rings, too, as does Jupiter. And Earth
may once have been a ringed planet.
-- Robert
Roy Britt
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