John (Denker)... Sorry we're having problems, but I think you are using words interchangably that are not synonyms.
You are using ecliptic and orbital plane as synonyms. They are not. The orbital plane is, well... the orbital plane. The ecliptic
is the intersection of the orbital plane with the celestial sphere. The celestial sphere is polar defined. Therefore, if the pole
moves with respect to the fixed stars, then the stars change their locations on the celestial sphere. And the orbital plane, as you
said, stays with the fixed stars, so that means the ecliptic goes to a new position on the celestial sphere.
And to pick more nits, when you quoted what you said earlier
"Yes, but that's almost trivial to observe. Just watch the motion
of the sun across the sky and keep track of its position relative
to the fixed stars. This defines the ecliptic. Note that the
ecliptic (concept #2) is defined without reference to the north
pole (concept #1)."
And I said "I don't see this."
And you said "What specifically is the problem."
There are two problems (1) physics definitions, (2) context of our discussion.
(1) The ecliptic is defined as the intersection of the orbital plane with the celestial sphere. The celestial sphere is polar
defined. Therefore the ecliptic is drawn on a sphere that is oriented with respect to the north pole.
(2) When you said the quote above (Yes, but that's almost trivial...), you were responding to my statement, "It seems we first have
to know what way the solar-system angular momentum vector points." So I said I didn't see this, and I still don't. But in your
later post you took this out of context and made it appear your quote was a response to a different thing I said. Indeed, in your
last post you quoted me, then anwered,
(Edmiston) I don't see how it shows us anything about the orientation of the vector
that represents the total solar system angular momentum.
(Denker) Indeed it doesn't, as I said. Specifically I said:... <snip>
That's not true. In you earlier post you specifically said your words (Yes, but that's almost trivial to observe...) in response to
my statement about finding the solar system angular momentum.
Please don't quote our discussions out of context.
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.