How Would You Define a Planet?

It doesn't come easy asks: "The argument over the definition of a planet continues. So far, two definitions are favored but without much consensus so far: base the definition of a planet simply on an object's size. Pluto would be near the lower limit and the newly discovered Kuiper Belt objects could also qualify, giving us 10 or 11 planets so far; or define the single dominant body in its immediate neighborhood as the only qualifying object for planetary status. If no one body dominated (such as the millions of individual asteroids in the asteroid belt) then none would qualify for planetary status. In this case Pluto would be disqualified (Neptune would be the dominant body in Pluto's region of space), and the newly discovered Kuiper Belt objects would also fail to qualify. The International Astronomical Union (IAU) working group charged with pinning down the definition of a planet may vote on the proposals within the next two weeks (or they may decide to start all over again with something new). Maybe Slashdot readers can give them some help. How would you define a planet?"

Comments

howabout...

[circletimessquare]

anything with an appreciable atmosphere that is NOT a gas giant = planet ...REGARDLESS of what it orbits

therefore, mercury would NOT be a planet (more like a moon of the sun)

and titan, even though it orbits saturn, WOULD be a planet

i think that makes most the most sense: what an object orbits shouldn't matter, it's composition should be the largest consideration

some other nomenclature can address what it orbits ("a moon of the sun" or "a planet of saturn")

it should be considered either

• a moon (like mercury or pluto)
  
  
• a planet (like mars or titan)
  
  
• an asteroid (like deimos and phobos... called moons of mars, they are clearly NOT moons, but captured asteroids of the sun) if it is not spherical
  
  
• and then we have your comets

REGARDLESS of what it orbits