On Fri, 10 Apr 2015 17:12:44 -0600, Chris L Peterson
wrote this crap:


Essentially all planetarium apps calculate precession and use it for
plotting the sky in the past and future. Keep in mind that the values
used for long time scales are approximations, and not very good ones.
Accurate calculations of precession beyond a couple thousand years in
either direction don't exist.

I don't believe you. At the university I went to school at, I was
very familiar with the planetarium. The stars were projected on the
ceiling dome with a globe which had lights attached. The lights were
fixed which could not have provided precession.

Perhaps there are newer types which allow for precession, but I
haven't been into a planetarium in 35 years.


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