Monday, October 31, 2005

Pluto now has three moons

The solar system gets a little weirder every day:

I find it amusing that people have big heated debates about the definition of a planet. The problem is that you can't really define a planet; if we used the definition "anything bigger than pluto" then we'd have to count all the Kuiper belt objects that we are going to discover soon that are bigger than Pluto. So that's a bad definition. I think the best thing to do is to just not have a definition of a planet; planetoid is the term astronomers use to describe anything just about any rocky piece of crap in the solar system (comets, planets, asteroids are all planetoids). I think we should just define a planet as "mercury through pluto" and be done with it. Maybe if (when) we discover a nice earth-sized ball of ice way out in the Kuiper belt or Oort cloud (which is actual pretty likely), then we can add an eleventh (that is, assuming that the IAU doesn't strip 2003 UB313 of its rightful place among planets!)