Re: North Pole

[Michael Edmiston <edmiston@BLUFFTON.EDU>]

To answer Jim's questions as simply as I can, and using my understanding of the situation.

> The Earth's spin axis precesses such that we get a moving polar star.

Yes, with a period of 26,000 years.

> Is it also the case that the orbital axis precesses?

Not that I know of, that is, I am unaware of having seen anything about this in any astronomy source I have read or consulted.  It
could be that it does, but with a period too long for us to notice, or an amount too small for us to notice.

> Does the angle between the orbital plain and the spin axis change?

Yes.  If the spin axis precesses, and the orbital axis does not (or precesses at a different rate or with a different angle) then
the angle between the spin axis and orbital plane must change.  This is exactly what I said in my last post when I said the ecliptic
(orbital plane) would change its position on the celestial sphere (celestial sphere being defined by the spin axis).  Sorry, Jim,
that I did not simply say it as "yes."

Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Chair of Sciences
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.