Originally Posted by Doodler

The foundation of my position on what makes a planet, and my opposition to the current trend in trying to define one, is that a body is a body, no matter where it is. A star is a star, whether it forms inside a galaxy, between a galaxy, orbits a galaxy, or is shot from a galaxy. No matter where it is, a star is a star is a star, the physical properties of the body define its label.

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3) Must either be an independent body or of at least equal status to a co-orbital body. Meaning, its either on its own, or its not the satellite of another major body. By establishing mass equilibrium as a clearly defined, non-arbitrary break point, you can look at a binary set of solid objects like Earth-Moon and Pluto-Charon and clearly say "Earth is the planet" and "Pluto is the planet". The actual sizes of the bodies isn't relevent, its how they relate to their companions in their particular circumstances.

Now #3 to me is actually negotiable. I don't see any particular crime in saying we have some satellite planets in the solar system. The Moon, Io, Europa, Ganymeade, Callisto, Titan, Triton and probably some of the larger moons of Uranus, are potentially deserving of planet status because of their very clearly planet like composition. Keep in mind, as I see it, location and orbit aren't relevent to the definition because it creates unnecessary overlap. A body is, or it is not.