"Roger Stokes" wrote in message ...
"David Harper" wrote in message
om...
"Jo & MickD" wrote in message
...
Why do the rings on Saturn look so perfect ie have perfect looking gaps
around them.
How does this actually happen or work?????????

Gravitational resonance with Saturn's other moons is one of the
primary factors. So something breaks up in Saturn's orbit. For
millions of years you have just a nebulous debris ring. Over time,
debris is tugged on by Saturn's moons, which orbit it in regular
intervals. Over time, the debris particles reach equilibrium orbits
due to this tugging as well as impacts with other debris.


Has Saturn always had rings, or do we just live in a period when something
"broke up" a few million years ago?

Good question. Short answer: no. To have always had rings, it would
need a constant supply of material. So we're kinda seeing it at one
of it's "finest mega-eons", or whatever. The rings will still be
there for millions of years to come, maybe tens of millions, maybe
hundreds. I'm not sure how fast they're decaying, other than it's
very, very slow.

Are Saturn's rings slowly depleting due to collisions and radiation
pressure?

Good question again. Disclaimer: I'm not 100% sure. Collisions
might be a small part. Radiation "pressure" I wouldn't think would be
a factor, since on one side of the rings radiation is against it, and
as the debris in the rings orbits to the other side, radiation is
helping (adding kinetic energy). I would guess gravitational decay
and small deviations from other gravitational bodies (Jupiter,
interactions between it's own moons, etc) are probably bigger factors.

Could all the gas giants possess massive rings from time to time?

Probably, yes. Mars probably could too, although they wouldn't be as
spectacular since there's not any moons large enough to induce
gravitational resonance. Earth probably couldn't since the moon is so
dang big by comparison (it would tug TOO hard on one side and the
rings probably wouldn't be too stable). Also, Mars' gravity is really
small by comparison to gas giants, so it would have to be very unique
circumstances for its gravity to grab something and rip it up into
ring material.

Dave