🚀 go-pugleaf

In article <57h7tc$e39@gap.cco.caltech.edu>, alexchen@cco.caltech.edu
(Yebo Chen) wrote:

> timberwoof@themall.net (timberwoof) writes:
> 
> >I read about preliminary work on that theory about twenty years ago in
Science News. Someone had made a simple computer simulation of colliding
terrestrial bodies and found some combinations of planet sizes and
relative speeds that fit very well with the current situation 4.5 billion
years later. I read about it again more recently in Scientific American. 
> 
> >The math works; the geology works. I'm convinced. :)
> 
> Question:  Isn't there a possibilty that the moon was formed at the same time
> as the earth?

Yes ... and no. 

You can take the rate at which the Moon's orbit is decaying and
extrapolate backwards for a long time ... and you end up with scary
results. I don't recall the precise details, but I think you end up with
two planets spinning around way too fast for their own good. 

However, if you accept for a moment the idea that the Earth was bigger and
got hit by something pretty big and very fast, you get a result that fits
with what we observe today. The thing that hit the Earth goes on, and the
ejecta go in three directions: back to the Earth, into orbit as the Moon,
and all over the solar system. Some of these occasionally hit the Earth
again. Tektites are meteorites that originated in this event or in later
impacts on the moon.

-- 
timberwoof@themall.net
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