Round 1: My definition is better than your definition

7:50: Neil kicks off the evening explaining that the flap over whether Pluto should be called a planet or not was actually a debate about what a planet is, and then if Pluto fit into that definition.  Funny.  We like to think a science as hard as astronomy would have this kind of question down cold. I'm sensing a lot more "social" ingredients have been cooked into this science cake.



Reactions from the debaters:


-Most astronomical classification schemes are based on observation, not the process by which an object (like a planet) was formed.

-When Captain Kirk shows up somewhere and looks out the window, you can tell that the thing he's looking at is a planet. (Now you're speaking my language)



Sara: No one seems to care about the definition of planets except the people discovering them.



Gibor: Much of the arguments are over what to call Brown Dwarf Stars. To get media attention, some people say they've found a planet instead of a BDS.

This sets off lots of reaction:


-What we've got is an adjective v. noun issue. We have books that are encyclopedias, dictionaries, etc. Why not just have adjective-based planet classification scheme? We have big planets, small planets. They're all just planets.

-Classification is meant to facilitate communication.


-If roundness is part of the definition, what if something that was round gets hit with something and is no longer round? Is it still a planet?



This sets off a very cool debate about whether a classification system should apply just in the present tense or must it include past and future.



Mark: Ceres was first called "Asteroid" because it looked like a star (prefix "aster"). But then when we looked at it through the Hubble, we saw it was round. Now we've discovered that it has an ocean, and we have to send our probe into a higher orbit so we don't risk contamination. Compare THAT to the small pieces out there.



Sara: Now we see what the debate is really about. Geophysicists arguing it's what the objects are and the Dynamicists insisting it's what the object does.