This discussion about Polaris and true north overlooks a phenomenon known as the
precession of the equinoxes. I suspect that this undelies the original question.
 There
seems to be a confusion between this an Proper Motion (which is, in effect, the
changing position of any star relative to the sun as the galaxy rotates, a very
slow
matter).
 
Basically, the earth's axis wobbles, with the imaginary line through the rotatio
nal
poles of the earth tracing a circle in the sky once every 26,000 or so years. It
's
not, therefore, correct to state that Polaris is still exactly where it was thou
sands
of years ago. It's well known that Alpha Draconis marked the pole around the tim
e the
Giza pyramids were built, c 2800 BC. The rate of change works out to be someting
 in
the region of 1 degree 23 minutes of arc every century, which is actually quite
significant, though not too bad for historical archaeologists. If we're looking
at
medieval or earlier civilisations, then it does become a real problem and it wou
ld be
worth talking to an astronomer, who will be able to give you formulae (or even a
computer program) to calculate the effects of precession.
 
As an aside, it's probably worth noting that even today Polaris only *approximat
ely*
marks the north celestial pole: it's a few minutes of arc from it, which means t
hat it
will appear to move in the field of view of even a small telescope if observed f
or a
short while.
 
--
Keith J Matthews
 
[log in to unmask]
 
University of Liverpool,
Chester Archaeology,
West Cheshire College
 
http://www.fortunecity.com/village/portillo/2/index.html
 
"The Road of Excess leads to the Palace of Wisdom" - William Blake