About Equinoctial Precession

The equinoxes do not precess linearly with time. Instead, their rate of precession increases to a maximum and then decreases to a minimum over a period of 38,830 years as the inclination or “obliquity” of the Earth’s axis relative to the ecliptic oscillates between a minimum rate of 73.75 years per degree, while in 26,550 B.C. they were precessing at their maximum rate of 68.8 years per degree. On the average, they take 71.28 years to move one degree, not 72 years as is often quoted. Hence one precessional Great Cycle actually spans an average of 25,660 years. However, more recently this cycle has been lasting longer than this average. Measuring back from 635B.C., computer simulations indicate that the preceding precessional half cycle took 13,195 years to complete, 365 years longer than the time for an average half cycle.

A map showing the constellations of Taurus and Orion as they appeared 15,860 years ago. The projection parallel to the ecliptic of Taurus’ upper horn and the upward projection of Orion’s club appear to indicate the galactic anticenter.


Ancient Knowledge of the Galactic Plane’s Location

The design of Scorpius also suggests that these ancient constellation artisans knew the precise orientation of the galactic plane. The Scorpion’s thorax, formed by the stars Sigma, Alpha, Tau, and Epsilon Scorpii , 15,860 years ago was oriented almost exactly from Epsilon Scorpii, to the tip of the stinger, Upsilon Scorpii would have been off normal by just four thousandths of a degree! Epsilon Scorpii has the highest proper motion of all stars in the Scorpius and Sagittarius constellatons, so it could very well have been intended as a sighting star, with Upsilon Scorpii as its marker point.

The constellations Scorpio and Sagittarius plotted in celestial coordinates.

A map showing the constellations of Scorpius and Sagittarius, as they would have appeared 15,860 years ago. Sightings are plotted for the Archer’s arrow for various dates. Shapley’s Galactic center position estimate is shown for comparison. Note that this map is plotted in galactic coordinates rather than celestial coordinates to represent the constellations with the least amount of cartographic distortion.


The zodiac’s moving-arrow pointer in Sagittarius is quite a clever device. Not only does it indicate the approximate location of the Galactic center, but it also serves as a chronometer that designates an important date in the past.

From Earth Under Fire by Paul La Violette

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