Hey frog, thats interesting, I really thought I'd come up with a lot of this by myself.
I guess I have the inventors 'bug' - sure I invented it - just not first. I guess that is one of the points I was trying to get at, the Egyptians, and the Sumarians (and their teachers ahem) - were at it long long ago.
Unless they just guessed that pluto was hanging about 4000BC+. ;-)
Great links will check it out buddy and get back to you about what I think
Peace,
A