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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.space
Subject: Re: Lagrange Points
Message-ID: <5000@utzoo.UUCP>
Date: Fri, 1-Feb-85 22:28:55 EST
Article-I.D.: utzoo.5000
Posted: Fri Feb  1 22:28:55 1985
Date-Received: Fri, 1-Feb-85 22:28:55 EST
References: <298@ho95b.UUCP>, <3347@alice.UUCP>
Organization: U of Toronto Zoology
Lines: 18

> L4 and L5 are only stable if the mass ratio of the two primary bodies
> is large enough.  I'd have to do some figgurin' to reconstruct the
> limiting ratio, but as I remember, the Earth is just barely large
> enough to make the Earth-Moon L4 and L5 stable.  A corollary is that
> the hotdog-shaped stable regions around the Earth-Moon Trojan points
> aren't very large or `deep'.

As I recall it, the threshold is about a 30:1 ratio.  The Earth/Moon
system has about an 80:1 ratio, I believe, which would make things a
bit more favorable than Tom suggested.  But I'd have to look all this
up to be absolutely sure.

Note to people wanting a simple explanation of why the ratio has to
be in excess of a threshold:  as far as I know, there isn't one.
You just have to work through the math.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry