Re: [Utah-astronomy] IAU Draft Definition Of Planets And Plutons

Classifying Charon as a planet poses a knotty problem. It's true that it doesn't exactly orbit Pluto, that they are locked together and in effect orbit each other. But isn't that the case for all planet-moon systems?

If my spotty memory serves, the difference in the Pluto/Charon system is that the center of mass is outside the body of Pluto, differentiating it from the others you mention. Of course, my spotty memory may not serve...