[physics/0407108] On the possible discovery of precessional effects in ancient astronomy

[physics/0407108] On the possible discovery of precessional effects in ancient astronomy:

 "The possible discovery of astronomical effects due to precession - such as the shift in the declination of heliacal raising of bright stars or the precession of the equinoxes - is reviewed for various ancient cultures in the world. Although definitive evidence of the discovery is still lacking, the quantity of hints (for instance, coming from ancient Egypt) is impressive and stimulating in view of further research."

"The earth rotates around its axis in 24 hours, and the earth’s axis rotates around the axis orthogonal to the ecliptic, describing a cone. Thus, the motion of the earth is similar to that of a top: the earth precedes. The period of this movement is extremely long with respect to human life, since the axis completes a cycle in 25776 years.

Precession has a very important consequence on long-term naked eye astronomy. First of all, the prolongation of the earth axis on the celestial sphere defines astronomical north. The direction in which astronomical north points – possibly indicating a star, thereby a pole star – changes therefore continuously in time. Today’s pole star (our Polaris) will resign to be the pole star in a few centuries, and all the stars which lie close to the circle described by the pole (actually not exactly a closed circle, due to perturbations) will become “pole stars” one time each precessional cycle. For instance, in Palaeolithic times, the north pole crossed the Milky Way and the Pole star in 15000 BC was Delta-Cygnus. The north-pole sky was therefore completely different from ours; it was probably depicted in a fresco of the famous Lascaux grotto (Rappenglueck 1998)."

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