Re: Question from my 7 year old son

From: Sam Wormley (swormley1_at_mchsi.com)
Date: 03/24/05 

Date: Thu, 24 Mar 2005 17:49:50 GMT

Richard Tobin wrote:
> In article <mIq0e.14514$fn3.8659@attbi_s01>,
> Sam Wormley <swormley1@mchsi.com> wrote:
>
>
>> See: http://www.mhhe.com/physsci/astronomy/fix/student/chapter12/12f36.html
>> The ring material is inside Saturn's Roche distance (tidal forces are
>> strong enough to pull apart material that tries to clump). Good question
>> from a 7-yr old.
>
>
> That diagram shows a single Roche distance. But the distance depends
> on the size of the satellite (small rocks can survive closer than
> large ones). So what is the diagram representing?
>
> -- Richard

   An approximation is based on

   D_roche = 2.42 R (Saturn's Density/Satellite's Density)^1/3

   so it's not so much the physical size, but the density of the
   object in orbit--leaving rocky objects fairing better than icy
   objects under the tidal forces of Saturn.

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