If Caronte is nominated to be a planet, why not Europe or Titan?

Question

(Caronte the moon of Pluto).

Answer 1

Charon and Pluto form a double planet, in the new proposal. Charon is so big, that the center of mass (balance point) between Pluto and Charon is actually outside Pluto - so it's more like they move around each other rather than only Charon doing the moving. But with Jupiter and its moons (Io, Europa, etc.) the center of mass is very close to the center of Jupiter, well inside the planet. So the large moons of the outer planets would not qualify as planets themselves.

Currently, the center of mass between Earth and our Moon is not the center of Earth, but is rather not too far below Earth's crust. And the Moon is slowly (about 4 cm per year) moving away from Earth. This means that in 40 million years from now or so, the center of mass will be outside of Earth. At which point (according to the proposed new definition) Earth and our Moon will become a double planet. Weird, eh? It's really all semantics, in the end.

Answer 2

Pluto's large moon is Charon, and it's nominated to be a planet because it does not exhibit normal orbital patterns (namely that it doesn't behave like a normal moon). Titan (Saturn's largest moon) is a natural satellite of Saturn and not considered to be in orbit around the sun.

Answer 3

the key is the orbit ( they are leaning toward round with its own orbit around the sun ) and in the case of Caronte it does not orbit Pluto they orbit a shared point in space

Answer 4

I'm pretty sure Europe won't ever be considered a planet because it's always been a continent. The former Soviet Union did have several satellite states, however.