>  Hi Randy, 
>   
>  I figured out the problem I was having -- the test1.txt and test2.txt files 
>  don't actually move.  The planets.txt works fine.  I have another quick 
>  question though.  When SIZE is 1024, the whole thing doesn't show up on my 
>  computer screen (I can see about a quarter of it).  I can only see the whole 
>  turtle window when SIZE is smaller, like 512.  Should I leave SIZE as 1024 
>  and assume that it's just my computer settings?  Or can I make SIZE 512? 
>  Also, how do I know that my program is going fast enough? 
>   
>  Thanks, 
>  Rachel 

Not a big deal either way in terms of size.  Probably can leave the
size at 1024.

Not as important to know your "program is going fast enough," as it is
to know for sure that your code is doing the algorithm it's supposed
to do :)  In other words, if it's doing the "right thing," it would
naturally be "fast enough."

Randy