Re: The Astronomers Giveth and the Astronomers Taketh Away

"Aaron Denney" <wnoise@xxxxxxx> wrote in message
news:slrndenlru.3np.wnoise@xxxxxxxxxx
> On 2005-07-30, Justin Bacon <triad3204@xxxxxxx> wrote:
> > Whichever definition you choose (and I'd prefer one with meaning in the
> > natural world, not just a round figure in an arbitrary measurement
> > system), I would like to see an exception made for moons.
> > I think there's a clear distinction between "planetary object orbiting
> > the sun" and "planetary object orbiting a larger body which is orbiting
> > the sun".
>
> But ... there's not. Both Earth and Luna can be considered as
> orbiting Sol, while perturbed slightly by the presence of the other
> body in nearly the same orbit.
>


However, the centre of gravity of the Earth-Moon paor is _inside_ the
Terrestrrial globe, which will do as a convenient test for being a satellite
rather than a planet. Iow if Luna were about one-third more massive (or was
further from the Earth by the same amount) it would count as a planet, but
as things stand it can remain a satellite.
--


Mike Stone - Peterborough, England

Seeking the answer to the ultimate question of life, the universe and
everything is not a task for cowards.

It is essential to show some forty-twode


.

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