• Question: If pluto was classified as a planet then wouldn't the other rocks and objects in outer space be classified as a planet as well?

    Asked by angelo775 to Bob, Katie, Nisha, Sallie, Vee on 28 Jun 2012. This question was also asked by mshariffali99.
    • Photo: Sallie Baxendale

      Sallie Baxendale answered on 28 Jun 2012:

      According to the most recent definition of a planet (2006), a proper planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.

      Pluto has been demoted because it does not dominate its neighborhood. Charon, its large “moon,” is about half the size of Pluto, while all the real planets are far larger than their moons. In addition, real planets “sweep up” asteroids, comets, and other debris, clearing a path along their orbits. Pluto’s orbit is a bit too untidy. So it is no longer a true planet but is now classifed as a dwarf planet. There are more than 40 of these dwarfs in our solar system and more are found every year, including Xena, a distant object that is actually slightly larger than Pluto.

    • Photo: Bob Bonwick

      Bob Bonwick answered on 2 Jul 2012:

      Sallie has it there.

    • Photo: Vee Mitchell

      Vee Mitchell answered on 3 Jul 2012:

      mmmm – OK – learnt something else today.

Comments

  • Photo: onethrickpuppy

    onethrickpuppy commented on :

    Now Pluto is a part of what’s been called the Kuiper Belt with a lot of other “planet” like things that are just like Pluto that they’ve been discovering. They were uncomfortable with calling them all planets because of the obscurity of the definition of a planet from it being defined a long time ago when they didn’t know much /about/ them in the first place. Now because of the constant discovery of new planet-like formations and just discovering more about the planets themselves, what we call a planet has an ever-changing definition. Also because of the sheer amount of the Pluto-like formations in the Keiper Belt to class them all as planets and name them for such would have taken a while and would make it so much more difficult to learn what was actually /in/ our solar system. Better to just do like they did and just class Pluto as something else along with all the other Pluto-like formations. Pluto is now known as a dwarf planets and there are at least three dwarf planets within Pluto’s region in the Keiper Belt.

    But don’t worry, Pluto. I’m not a planet either.

    Hope I’ve been of help! ^-^