[extropy-chat] Re: SPACE: new planet?
neptune at superlink.net
Fri Feb 20 22:21:32 UTC 2004
On Friday, February 20, 2004 4:17 PM Joseph S. Barrera III
joe at barrera.org wrote:
> I have an unexplainable fascination with the Kuiper Belt,
> so naturally I have a daily google news alert.
> This is what poured in today...
> I think it's pretty clear we only have 8 planets,
> and a bunch of planetesimals.
Define "planet" and "planetesimal" in a way that's not circular to your
division of the solar system. It might be better to say there's a bunch
of different stuff orbiting the Sun. Some of that stuff fits well into
the category of rocky bodies, some fits into gas bodies, and some into
frozen volatile bodies. Some of each of these three categories is big
enough to demand special attention. Well, true, there don't seem to be
any gas midgets -- just gas giants.:) But there are rocky bodies like
the Earth and those in the asteroid belt and there are frozen bodies
like comets and KBOs.
I can see a fuzzy, but helpful line between planet and star and the
differentiation between planet/planetesimal is likewise helpful, but
there will always be marginal cases, don't you think?
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