Sometimes it is easier to bypass non-descript responses and move on to why this issue is important for multiple reasons. It is, therefore, demonstrating dynamics with purpose rather than contending with those who live off deficient or contrived views.
The North and South Poles rotate across the light and dark hemispheres of the Earth and parallel to the orbital plane as a function of the planet's orbital motion. It gives researchers a reference other than the central Sun. It can be complicated as it
requires a new framework ( actually the original framework for the calendar system) where the precession of the equinoxes is accounted for by the proportion of rotations to orbital circuits not being exactly 1461 rotations for 4 orbital circuits.
Copernicus was obligated to use the Ptolemaic framework so there was always going to be an issue accounting for the seasons and the precession of the Equinoxes so I will leave the original statement and De Revolutionibus mutation as a testament to this
real quandary that can now be resolved by introducing a new framework which is a big deal.
"The third is the motion in declination. For the axis of the daily rotation is not parallel to the axis of the great circle, but is inclined to it at an angle that intercepts a portion of a circumference, in our time about 23 1/2°. Therefore, while the
centre of the earth always remains in the plane of the ecliptic, that is, in the circumference of the great circle, the poles of the earth rotate, both of them describing small circles about centres equidistant from the axis of the great circle. The
period of this motion is not quite a year and is nearly equal to the annual revolution on the great circle." Copernicus, Commentariolous
" I said, however, that the annual revolutions of the centre and of inclination are nearly equal. For if they were exactly equal, the equinoctial and solstitial points as well as the entire obliquity of the ecliptic would have to show no shift at all
with reference to the sphere of the fixed stars. But since there is a slight variation, it was discovered only as it grew larger with the passage of time. From Ptolemy to us the precession of the equinoxes amounts to almost 21° " Copernicus, De
Revolutionibus, Chapter 11
The circumference where the Sun remains in view at the North Pole and remains out of sight at the South Pole is now contracted to a very small circumference and the switch occurs on the September Equinox as the North Pole rotates into the dark hemisphere
and the South Pole rotates into the light hemisphere for 6 months. It has to be considered a rotation despite Galileo's objection and Copernicus's later mutation-
"From what I see, did not understand very well- was a certain experiment which I exhibited to some gentlemen there at Rome in partial explanation and partial refutation of the "third motion" attributed by Copernicus to the earth. This extra rotation,
opposite in direction to all other celestial motions, appeared to many a most improbable thing, and one that upset the whole Copernican system. . . . What I said was designed to remove a difficulty attributed to the Copernican system, and I later added
that anyone who would reflect upon the matter more carefully would see that Copernicus had spoken falsely when he attributed his "third motion" to the earth since this would not be a motion at all, but a kind of rest" Galileo
The diurnal rotational velocity at the North and South Poles is 0 mph, however, as a function of its orbital motion, the Poles rotate the equivalent of the circumference of the Arctic and Antarctic Circles over the course of an orbit.
I now sufficiently appreciate that theorists and their cheerleaders don't work with geometry, observations and visible dynamics so are unlikely to make sense of the historical discussion that has been laid out here, wish it could be different but there
is an easy door into all the issues which expand perspectives rather than contend with faulty ones.
https://sol24.net/data/html/SOHO/C3/96H/VIDEO/
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