Message-ID:	<32F7B3BD.3A6A@pobox.oleane.com>
Date:	Tue, 04 Feb 1997 23:10:05 +0100
From:	Francois Charton <deef AT pobox DOT oleane DOT com>
Organization:	CCMSA
MIME-Version:	1.0
To:	Benjamin D Chambers <chambersb AT juno DOT com>
CC:	djgpp AT delorie DOT com
Subject:	Re: ellipses at an angle
References:	<199702030225 DOT UAA22378 AT mail DOT texoma DOT net> <19970203 DOT 183342 DOT 4575 DOT 2 DOT chambersb AT juno DOT com>

Benjamin D Chambers wrote:
> 
> Wasn't it Galileo who used ellipses like this to model the solar system?
> (Might of been Newton, I was sleeping through that part... the general
> equations and such get a lot more fun than a bunch of history :)
> 

Sorry all, this is quite off topic, but just for the sake of history...

Galileo certainly did not care about ellipses : for him, everything 
moved in circles, with constant acceleration.

The first one to spot ellipses in planetary movement was Kepler (it is 
actually his First Law, published in 1609). 

The explanation (in terms of equations) of why it is that planetes move 
(approximately) as ellipses, was derived by Newton, in 1687.

Francois

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