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Precession of the Equinoxes

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Old November 15th 18, 08:24 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Precession of the Equinoxes

The moon in its monthly orbital circuit of the Earth will register the shifting of either the North or South poles relative to the Sun or the Earth's circle of illumination and parallel to the Earth's orbital plane. Of course a telescope is needed on the moon to process this annual event.

Copernicus originally got the motions of the North/South polar latitudes correct but traded it for axial precession by the time he wrote De Revolutionibus -

"The third is the motion in declination. For, the axis of the daily rotation is not parallel to the Grand Orb's axis, 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 earth's center always remains in the plane of the ecliptic, that is, in the circumference of a circle of the Grand Orb, the earth's poles rotate, both of them describing small circles about centers [lying on a line that moves] parallel to the Grand Orb's axis." Copernicus


Effectively the motion looks like this in respect to the circle of illumination -


The ancient neolithic monuments affirm that the polar latitudes exist in the same position as they did over 5000 years ago on the solstices and equinoxes so the Precession of the Equinoxes is from a different cause.

The original reference frame for timekeeping as an astronomical event is the delay in the first annual appearance of Sirius which provides a close but not exact proportion of rotations to orbital circuits. The drift between time keeping and planetary dynamics is to add 24 hours to bring days and dates into the fixed orbital position of the Earth. It is not entirely exact and this is where the secondary orbital drift comes in which astronomers recognise as the Precession of the Equinoxes.

The reason Copernicus shifted from his correct view to an unsatisfactory one was to try and make fit dynamics into the timekeeping system which provides accurate predictions within the calendar framework. In this respect dynamics is not subordinate to human timekeeping .

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