Originally Posted by Assa2:
“Point 3 is a complete sham in my view. What does it mean? There's a hell of a lot of 'debris' orbiting around the inner solar system so you could easily argue that none of the inner planets are planets by that criteria. How for does a candidate planet's orbit extend? What constitutes it's neighbourhood? What constututes clearing?”
“Point 3 is a complete sham in my view. What does it mean? There's a hell of a lot of 'debris' orbiting around the inner solar system so you could easily argue that none of the inner planets are planets by that criteria. How for does a candidate planet's orbit extend? What constitutes it's neighbourhood? What constututes clearing?”
Well, Assa2, it essentially means that that a planet should be a unique and distinct body which has a discernable discrete orbit around the parent star. lt should not be one of a number of similar bodies orbiting in the same broad orbital band which would cover the asteroids and ice asteroids (Kuiper Belt Objects) which are basically builder's rubble left over from the formation of the Solar System.
If Ceres http://en.wikipedia.org/wiki/Ceres_%28dwarf_planet%29 had been the only celestial body between Mars and Jupiter and had Pluto been the only world beyond Neptune then they might well deserve the term planet but that isn't the case. Indeed, Pluto's actually smaller than Eris http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29 and my money is on more equally large, or even larger, bodies being out there. More here: http://en.wikipedia.org/wiki/IAU_definition_of_planet



