Comment Definition bad, vote wasn't consensus (Score 1) 118
A professional astronomer here, with some things to keep in mind:
* While opinions are divided on whether or not Pluto, and other 'dwarf' planets are full-blown planets, the astrophysics community, by and large, doesn't like - or adhere to - the IAU planet definition. It restricts the use of 'planet' to the 8 bodies in the solar system, ignoring the 5,000+ confirmed exoplanets. It goes to great pains to attempt a definition of the low mass range (which it fails at), and doesn't define the high end of the mass range. And the eligibility of those 8 bodies in 'clearing their orbital zones' is ill-defined (Shoemaker-Levy 9 and the Chelyabinsk meteor have entered the chat). If you look at the scientific discourse at astrophysics meetings - eg. the recent "Extreme Solar Systems V" conference in Christchurch, NZ - astronomers use 'planet' in a much more ecumenical fashion.
* A significant number of planetary scientists - the scientific community that matters, not us astronomers - have put forth a different definition of planet. The 'geophysical definition' of a planet is basically, "big enough to be a ball" - simple, elegant, and easy to explain to schoolkids. The 'big enough to be a ball' concept is rooted in actual physics, not tempest-in-a-teacup astropolitics.
* While it was apparently of paramount importance to define 'planet', the IAU hasn't made similar moves to define 'star', or 'galaxy', or anything else.
* While opinions are divided on whether or not Pluto, and other 'dwarf' planets are full-blown planets, the astrophysics community, by and large, doesn't like - or adhere to - the IAU planet definition. It restricts the use of 'planet' to the 8 bodies in the solar system, ignoring the 5,000+ confirmed exoplanets. It goes to great pains to attempt a definition of the low mass range (which it fails at), and doesn't define the high end of the mass range. And the eligibility of those 8 bodies in 'clearing their orbital zones' is ill-defined (Shoemaker-Levy 9 and the Chelyabinsk meteor have entered the chat). If you look at the scientific discourse at astrophysics meetings - eg. the recent "Extreme Solar Systems V" conference in Christchurch, NZ - astronomers use 'planet' in a much more ecumenical fashion.
* A significant number of planetary scientists - the scientific community that matters, not us astronomers - have put forth a different definition of planet. The 'geophysical definition' of a planet is basically, "big enough to be a ball" - simple, elegant, and easy to explain to schoolkids. The 'big enough to be a ball' concept is rooted in actual physics, not tempest-in-a-teacup astropolitics.
* While it was apparently of paramount importance to define 'planet', the IAU hasn't made similar moves to define 'star', or 'galaxy', or anything else.