Trepidation (history) Tremble
"SIR ISAAC NEWTON (1643-1727) is best remembered today as a physicist and mathematician. However, in his lifetime, Newton pursued more esoteric lines or research as well, including alchemy. Newton's 1728 The Chronology of Ancient Kingdoms Amended attempted to revise world history to demonstrate that Solomon was the first king in the world, and the Temple in Jerusalem mankind's first holy site. All others, he argued, were in imitation of Solomon and his Temple. In Chapter I, reproduced below, Newton explains the history of Greece, claiming that the Argonauts were the first sailors in the world, that their voyage was used to reckon time, and that the constellations of the sky represent primarily episodes from the Argonauts' adventure. The esoteric and revisionist history of the book leads many to consider it an occult work, closer to Newton's alchemical inquiries than his physics. The constellation Argo Navis, seen at left, representing the Argo, was later divided into several smaller constellations."
Gravity can do anything Sir Isaac Says It can
Over a century later precession was explained in Isaac Newton's Philosophiae Naturalis Principia Mathematica (1687), to be a consequence of gravitation (Evans 1998, p. 246). Newton's original precession equations did not work, however, and were revised considerably by Jean le Rond d'Alembert and subsequent scientists."
I do not think the Earth concave. And I don't believe in "Lord Steven Christ". I find his point about precession of the equinoxes interesting especially in light of Sir Isaac Newton's legendary fascination with the precession of the equinoxes and the Jason and the Argonauts myth.
Trepidation (astronomy) Oscillation
The origin of the theory of trepidation comes from the Small Commentary to the Handy Tables written by Theon of Alexandria in the 4th century CE. In precession, the equinoxes appear to move slowly through the ecliptic, completing a revolution in approximately 25,800 years (according to modern astronomers). Theon states that certain (unnamed) ancient astrologers believed that the precession, rather than being a steady unending motion, instead reverses direction every 640 years. The equinoxes, in this theory, move through the ecliptic at the rate of 1 degree in 80 years over a span of 8 degrees, after which they suddenly reverse direction and travel back over the same 8 degrees. Theon describes but did not endorse this theory.
A more sophisticated version of this theory was adopted in the 9th century to explain a variation which Islamic astronomers incorrectly believed was affecting the rate of precession. This version of trepidation is described in De motu octavae sphaerae (On the Motion of the Eighth Sphere), a Latin translation of a lost Arabic original. The book is attributed to the Arab astronomer by Thābit ibn Qurra, but this model has also been attributed to Ibn al-Adami and to Thabit's grandson, Ibrahim ibn Sinan. In this trepidation model, the oscillation is added to the equinoxes as they precess. The oscillation occurred over a period of 7000 years, added to the eighth (or ninth) sphere of the Ptolemaic system. "Thabit's" trepidation model was used in the Alfonsine Tables, which assigned a period of 49,000 years to precession. This version of trepidation dominated Latin astronomy in the later Middle Ages.
Islamic astronomers described other models of trepidation. In the West, an alternative to De motu octavae sphaerae was part of the theory of the motion of the Earth published by Nicolaus Copernicus in De revolutionibus orbium coelestium (1543). Copernicus' version of trepidation combined the oscillation of the equinoxes (now known to be a spurious motion) with a change in the obliquity of the ecliptic (axial tilt), acknowledged today as an authentic motion of the Earth's axis."