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Pluto: A Modest Proposal

By catdynamics on August 23, 2006.

Ok, time to stop the madness.
I propose consistent, competing definitons of planets; one leave Pluto in, the other not. Up or down vote.

The IAU now has a competing resolution that looks likely to delete Pluto as a planet, and the original IAU resolution is being voted on piecewise - which will likely leave an inconsistent mess.
As opposed to...

So here is a serious proposal; no more messing around, no more pretending to find artificial consistency from some favourite corner of microphysics (much as I like the dynamical definition.... it is actually quite stupid).

Proposal:

1) a planet is an sub-stellar object orbiting a star, whose mean radius is at least 1000 km

or,

2) a planet is a sub-stellar object orbiting a star, whose mean radius is at least 2000 km

Option 1) leaves Pluto in, and Ceres out, but may lead to new trans-Neptunian planets.
Option 2) leaves Pluto out, but makes sure Mercury stays in; it may or may not lead to new trans-Neptunian planets (if we find one as big as Mercury, can we just agree to call it a planet?)

That is it. No rationalisation, no funny games or semantics.
Strictly arbitary definition because that is what we feel like.
But it is consistent.

The ad hoc subcommittee on the Pluto issue was a mistake, deliberation needed to be public, obviously. I seriously propose the IAU defer the issue to 2009 rather than making a serious mess of it and leaving us all worse off.
Then we vote on the proposal above.

Chad also opines
He is right, by the way, astronomer do use really dumb units, but there is a reason for it...
- did I mention my PhD is physics? Ah, no, I'm going over to the dark side.... Aargh! Help, someone throw me a Lagrangian...

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The only units astronomers use that I think are dumb are magnitudes.

Don't get me wrong: log scales are great. But we didn't really need to have a negative log scale.

When it comes to parsecs and astronomical units and all the other things physicists bitch about, we're just choosing units that match the scales we're working on. Some of them go off and talk about fermis and amus and other equally arbitrary units.

-Rob