Is pluto really a planet or an asteroid from the kuiper belt?
It has been considered a planet since its discovery in 1930. The definition of a planet might change, however, especially after the recent findings of large Kuiper belt objects. Pluto might still preserve its status as a planet even if it does not fall within the scope of a new definition, mainly for historical purposes and to avoid confusion. I am personally in favor of the following definition: “A planet is any body not cirlcing another planet that is small enough not to be able to sustain nuclear fusion in its core [like stars], or derive substantial energy from gravitational contraction [like brown dwarfs], but large enough so that its own gravity makes it a spheroid”. Under such definitions, some bodies would be both Kuiper belt objects (KBO) and planets, while the smaller KBOs, having an arbitrary shape, would be just KBOs, or KBO asteroids. In any event Pluto might be a KBO, but it is presumably not just a large asteroid.
