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Den 15. jan. 2008 kl. 05.04 skreiv Herman Miller:

> Going back millions of years, even many of these relatively distant  
> stars will have moved quite a bit, and I don't even know enough to  
> have any idea how accurate are the projections that go back a few  
> thousands of years. Probably the motions of the nearer and faster- 
> moving stars are known more accurately than the more distant ones.  
> But this program doesn't adjust the distance or magnitude of even  
> the nearest stars over time as they move through the sky, so there  
> are bound to be errors the further you get from the present time.  
> Probably many of the stars that would be prominent in the  
> Pleistocene would be dimmer today and vice versa.

Possibly, but this would seriously affect only the nearest stars I  
think. I have a star catalogue published 1937, mine is a 1963  
reprint, with proper motions of the stars given pretty accurately. I  
bet they've refined them a good deal since then. Those proper motions  
are linear, so they give only an approximation of the real motion.  
Again the nearest stars are likely to deviate the most. From your  
description I assume that Starry Night Pro uses linear proper motions  
as well.

It wouldn't be beyond me to input the proper motions of the most  
prominent stars and so calculate their positions at any given time  
using some calculatory approach or other. But I guess some more  
readily machine-readable (and better) proper motion data must be  
available somewhere.

LEF