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=Edmiston=Denker
<snip>The celestial sphere is polar defined.
No, the celestial sphere, to follow M.E.'s example, is
the celestial sphere.
The celestial sphere has physical reality quite independent
of what coordinates, if any, somebody imposes on it.
By way of analogy:
-- Vectors are not defined by the coordinate system (if
any) in which somembody (if any) chooses to project out
components.
-- Numbers have a reality independent of the base or font
in which somebody (if any) chooses to write numerals.
I made it clear, I thought, that when I said the ecliptic
was not precessing, it was not precessing relative to the
fixed stars.
Therefore, if the pole
moves with respect to the fixed stars, then the stars
change their locations on the celestial sphere.
No, the fixed stars are fixed. This seems clear. Obvious.
Tautological. Changing your choice of coordinate system
does not cause things to move.
There are techniques for writing down the equations of
motion with respect to a changing coordinate system, but
these are far-from-elementary techniques. If anybody
really wants to get into this, we can get into it.
For a discussion of the methods of (and the importance
of) the coordinate-free approach to doing physics, I
recommend Misner, Thorne, Wheeler _Gravitation_.
And the orbital plane, as you said, stays with the fixed
stars,
and so it does
so that means the ecliptic goes to a new position on the
celestial sphere.
On a couple of occasions they renumbered the area-codes where
I lived. That doesn't mean that my house moved, or that my
phone moved, in any physical sense. Relabeling the coordinate
system is not "motion" or "precession" according to any
physics I've ever heard of.
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.
OK.
The celestial sphere is polar defined.
This is getting repetitive. This is still wrong physics
for the reasons described above.
Therefore the ecliptic is drawn on a sphere that is
oriented with respect to the north pole.
The physics of spheres is not oriented. Your chosen
coordinate system may be oriented in a way of your choosing.
Others may choose coordinate systems that they find more
convenient. The sphere is unchanged by any such choice.