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Den 15. jan. 2008 kl. 15.06 skreiv Mark J. Reed:

> (?) Since the orbital period of the galaxy is about 200 million years,
> does that mean the night sky from Earth would have looked pretty much
> the same 200 million years ago as it does today,

It doesn't, because the Earth and her Sun move with the other stars.  
The proper motions result from smaller (relatively) variations within  
that bigger circulation.

LEF