BTW...
...on Titan being a planet, I think you're probably right. The current thinking on Theia - the Moon-making impactor - is that it formed in one of the Earth-Sun L4/5 points. If a Mars mass can gather there imagine what accreted in the Saturn-Sun points... and the Neptune-Sun points. Hence both Triton and Titan could be captured planets - or KBOs/Centaurs to be precise.
Adam
