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Re: Sheparding Moons (wasAsteroids feel the Force)



Thanks Ron,

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!

It looks to me like they are sweepers which  have swept out a zone;
drawning in  the ring debris within each  moon's gravitational influence.
The remnant ring between the two moons is material in a zone equially
between the two gravities, else outside the gravity zone,  perhaps related
to the Roche Limit.

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.

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.  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?  I recall a
joke a while back which discussed the  reality of our  moon's mean distance
from the earth having been much closer in the paleo-past.   Second part of
this question and perhaps a new thread...Why is our moon moving away from
the earth over time?

Regards,
Elton Jones

PS I am having difficulties maintiaining a HTML vs NOn Html format  if
anyone (who cares) getting this letter in an unreadable form?

Ron Baalke wrote:

> The shepherd moon has the appearance of repelling the ring material.
> The moon contrains the material, not allowing it to spread.  It is all
> done with gravity (attraction).  It seems counterintuitive  but it
> is a 3 body problem.  The planet's gravity is involved in addition
> to the shepherd moon and the ring.  Here'a a photo of Saturn's F ring
> with two shepherd moons on either side of it:
>
> http://www.jpl.nasa.gov/saturn/faq.html#shepherd
>
>

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