Re: planets

Barry Garcia wrote:

> edheil@postmark.net writes:
> >(Moving even more off topic...)
> >
> >When I was a kid and into astronomy more than I am now, it was never
> >a widely held theory that the moon was the result of a collision with
> >another planet ripping a chunk out of the earth.  Is that widely
> >believed now or was it just a pet theory of the makers of this show
> >because it's, like, really dramatic?
>
> Well, the show went through three of the main theories, and the only one
> that made sense for earth was the planet strike theory. It nicely explains
> why earth has a moon 1/4 of it's size and the others do not. They
> explained three of the most popular theories (I only remember two):
>
> - If it formed from dust, it should have a larger iron core, and not be as
> devoid of water (crystals or otherwise) as it is. (the moon has a very
> small core and is practically bone dry)
>
> - if it was a planetoid caught in earths gravity, that wouldnt have worked
> because the moon is large enough to make it past the earth
More to the point, the moon would not have such a similar chemical
composition as the earth if there were not something that unites the origin
of the two.

>   It's not a very shocking theory, since in the early days of the
> formation of the universe there would be lots of planets and planetoids in
> the universe (Just look as some of the impact craters on the moon).
Surely you mean the formation of the solar system.  The early days of the
universe were quite a different situation.

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Tom Wier <artabanos@...>
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