IAU: "planet" defined, again
So, the solar system as we know it isn’t going to go without a fight. Astronomers here in Prague are unhappy with the proposed new definition of a planet, which would see the current tally of planets swell to twelve (and counting).
The formal discussion of the proposal is scheduled to take place tomorrow, over an hour at lunchtime. But already many astronomers have conveyed their objections to the Executive Committee of the International Astronomical Union (IAU) by email – and some are supporting a second, rival definition.
Today’s edition of the conference’s daily newspaper, distributed to all meeting-goers, Nuncio Sidereo III, carried a news flash beneath its masthead: “Planet redefinition proposal defeated by alternative idea in internal test vote!”
The alternative definition of "planet" argues that, on top of the IAU’s requirement that a planet be round, it must also be “by far the largest object in its local population”. The details are given in an online supplement to the newspaper. This definition knocks Pluto off its planetary pedestal (although offering it concessionary "dwarf planet" status), and destroys Charon and Ceres’ chance of promotion.
It was put forward on Friday 18th August at a meeting of the IAU working group concerned with the planets. Of the 100 people in this closed meeting, 50 voted for the new proposal, only 20 for the IAU’s suggestion.
Richard Binzel, one of the astronomers involved in coming up with the definition in the first place, says the IAU is doing its best to listen. He has been in a meeting all afternoon with the Executive Committee, revising the resolution proposal. Tomorrow’s newspaper, he says, will carry notice that a new definition is to be issued for discussion. That will be handed out on bits of paper at the lunchtime debate. I’ll be there to watch the arguments unfold.
[posted on behalf of Jenny]