Washington: One of the solar system`s most
evocative mysteries - the origin of Saturn`s rings - may be a
case of cosmic murder, new research suggests.
The victim: an unnamed moon of Saturn that disappeared
about 4.5 billion years ago.
The suspect: a disk of hydrogen gas that once
surrounded Saturn when its dozens of moons were forming, but
has now fled the crime scene.
The cause of death: A forced plunge into Saturn.
And those spectacular and colourful rings are the only
evidence left. As the doomed moon made its death spiral,
Saturn robbed its outer layer of ice, which then formed rings,
according to a new theory published online today in the
"Saturn was an accomplice and that produced the
rings," said study author Robin Canup, an astronomer at the
Southwest Research Institute in Boulder, Colorado.
The mystery of Saturn`s rings "has puzzled people for
centuries," said Cornell astronomer Joe Burns, who wasn`t
involved in the study and said Canup`s new theory makes sense.
One of the leading theories has been that either some
of Saturn`s many moons crashed into each other, or an asteroid
crashed into some of them - leaving debris that formed the
rings. The trouble is Saturn`s moons are half ice and half
rock and the planet`s seven rings are now as much as 95 per
cent ice and probably used to be all ice, Canup said. If the
rings were formed by a moon-on-moon crash or an
asteroid-on-moon, there would be more rocks in the rings.
Something had to have stripped away the outer ice of a
moon, a big moon, Canup said.
So her theory starts billions of years ago when the
planets` moons were forming. A large disk of hydrogen gas
circled Saturn and that helped both create and destroy moons.
Large inner moons probably made regular plunges into the
planet, pulled by the disk of gas.
These death spirals took about 10,000 years and the
key to understanding the rings` origins is what happened to
them during that time. According to Canup`s computer model,
Saturn stripped the ice away from a huge moon while it was far
enough from the planet that the ice would be trapped in a