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Re: Shepherding Moons


>I agree that the description is counter intuitive.  However , looking at
>the photo  I have an aternate view of the Sheparding Moons...I think they
>are wolves in...  er....  well you know the cliche`.  Instead of herding
>the ring  they have actually raided it!

Good observation.  If the moon is inside the ring material, then it will
clear out a gap inside the ring structure, and at the same time, keep
the ring edge it is near in check.  In fact, many of Saturn's
ring gaps have already been correlated with a moon.

>I  understand that the Roche Limit is 2.4 diameters (e.g.  sweeps out 5.8
>diameters: 2.4 x 2 plus 1)  and I don't know if this actually applies this
>discussion  but  I imagine similar dynamics are in effect.

The Roche limit is 2.446 times the radius of the planet.  All of the
known rings at Jupiter, Saturn, Uranus and Neptune are inside their
respective Roche limits.

>NEW Question:  As a moon /orbiting body encounters smaller meteoroid masses
>which impact it, each impact has a small but cumulative effect on inertia,
>which intern changes centrifugal tendancies which in turn governs orbital
>distance.  

Yes, there will be an effect, but it will be very small.

>IF this is true won't the moons tend to migrate? and IF I am
>correct will they not fall towards the planet as they slowdown?  

If the meteors hit the object consistently from the same direction, then
there will be a net effect. However,  I don't think the meteors are hitting 
the object from the same direction, and there is probably a lot of 
cancellation going on.  

Ron Baalke

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