...try these
http://journeybystarlight.blogspot....er.html?gclid=CMriurDfwJsCFUQA4woduDZxDA

and this, recommended by another poster. I had a query and got a response from a real live physicist in 4 days:
http://curious.astro.cornell.edu/index.php

Last edited by Raddy; 07/06/09 08:12 AM.