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Re: North Pole



Yes - the moon's orbit is tilted just about 5 degrees to the ecliptic - which is why we don't have eclipses every month. However, the earth-moon center of mass would stay in the ecliptic plane - the earth and moon would rise and fall through the plane as they mutually orbit about the center of mass. The only resulting
torque that I could imagine is due to the sun's gravity acting on the earth-moon unequal (non symmetric) distribution of mass about that center of mass point. My background on this isn't deep enough to know if there is any significant precession related to this - but I suspect not. It's not mentioned in any of the
astrophysics texts in my collection - only the precession related to the sun acting directly on the earth itself.

Bob at PC


paul o johnson wrote:

While reading Totality: Eclipses of the Sun by Littman, Wilcox, and Espenak, I learned that the moon's orbital plane is several degrees out of the ecliptic. So it would seem that the Earth-Moon center of mass is noticeably out of the ecliptic plane twice a month. This ought to cause Earth's orbital axis to precess.

poj

----- Original Message -----
From: "Jim Green" <JMGreen@SISNA.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Saturday, October 05, 2002 1:33 AM
Subject: Re: North Pole

I dunno Brian, I have been thinking about his for a few days and I still
don't understand, How about a more detailed tutorial for the
senile. Anyone else want to chime in as well?

Jim

At 06:19 01 10 2002 , the following was received:
A similar question was addressed recently on a navigation list.
While the motion in question does not seem to be fairly
described as precession, the Earth visibly moves out of the plane
of the ecliptic as a center of gravity effect of the Earth Moon center
of mass.

Brian W.

At 01:39 AM 10/1/02, you wrote:
The Earth's spin axis precesses such that we get a moving polar star.

Does the orbital axis precess?

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



Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen

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

Brian Whatcott
Altus OK Eureka!

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


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen

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


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

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