astronomical dissent
by John at 8/18/2006 08:03:00 PM
An alternate proposal at the IAU meeting would de-planetize Pluto by insisting that a planet be "by far the largest body in it's local population." Because pluto is a KBO (Kuiper Belt Object), it would be classed with all the other KBOs, some of which are larger than Pluto itself (for example, 2003 UB313, unofficially called Xena). It seem to me this proposal would also eliminate the issue of binary planets (the smaller would be called a satellite, unless the pair were of roughly equivalent size, in which case neither would be a planet, right?).
Besides that, the definitions of "local population" and "by far the largest" will need to be made less subjective.
In my opinion, the first proposal should be accepted, despite the likely difficulties (many small objects become planets, how round is round?) and the sometimes counter-intuitive results (Pluto/Charon as binary planets, and in the distant future, the Earth/Luna system as binary planets*). The definition of planet will be based on a physical feature - roundness due to gravitational collapse.
My guess is that neither proposal will pass and the issue will remain undecided, conservatively preserving the status quo.
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* The Moon is pulling away from the Earth at a steady pace. In a few billion years, the barycenter (center of mass) of the Earth/Moon system will be outside the Earth's sphere, and the Earth/Moon pair would be binary planets. For some reason, some people have a problem with this. The Moon is already a very disproportionately sized satellite for Earth to have, based on other examples in our solar system - to clarify that oddness by calling us binary planets (when it is applicable) seems appropriate.
Besides that, the definitions of "local population" and "by far the largest" will need to be made less subjective.
In my opinion, the first proposal should be accepted, despite the likely difficulties (many small objects become planets, how round is round?) and the sometimes counter-intuitive results (Pluto/Charon as binary planets, and in the distant future, the Earth/Luna system as binary planets*). The definition of planet will be based on a physical feature - roundness due to gravitational collapse.
My guess is that neither proposal will pass and the issue will remain undecided, conservatively preserving the status quo.
-----
* The Moon is pulling away from the Earth at a steady pace. In a few billion years, the barycenter (center of mass) of the Earth/Moon system will be outside the Earth's sphere, and the Earth/Moon pair would be binary planets. For some reason, some people have a problem with this. The Moon is already a very disproportionately sized satellite for Earth to have, based on other examples in our solar system - to clarify that oddness by calling us binary planets (when it is applicable) seems appropriate.
