Due to the pole of the equator revolving around the pole of the ecliptic, the equinoctial point (Vernal Point) moves backward with relation to the constellations at the rate of approximately 50" per year. It makes a complete revolution through the twelve constellations in the great cosmic year of 25,920 earthly years, or 2160 years to pass through one constellation, or to be more exact, sign of the sidereal zodiac. Thus the position of the first degree of Aries in the tropical or moveable zodiac moves slowly backwards through the sidereal, or fixed zodiac. The discovery of precession is attributed to the Hellenic scientist Hipparchus in 128 BCE, but it was evidently known to initiates very much earlier, as shown by the alignment of the pyramids and other ancient indicators. There is disagreement among authorities as to the exact position of the Vernal Point (0° Aries) at present, but all are agreed that it means we are approaching the end of the Age of Pisces and entering the Age of Aquarius.