http://bighead.poli.usp.br/juca/gravit.html

Javascript gravitation code v.1.1 (May 9th, 2007)
(c)2007 Felipe Sanches <felipe.sanches@poli.usp.br>

This program simulates gravitational effect.

This program is licensed under the GNU General Public License
 version 2 or later.

ChangeLog:
v1.1 (May 9th, 2007)
* Added tail effect

v1.0 (May 3rd, 2007 - First release)
* initial code
** simulation core
** basic rendering using <div>s