The equinoctial times, when day and night are equal in length, happen twice a year in March and September. It is only on 2 days of the year that the Earth’s axis comes to an exact 90˚ right angle with an imaginary line running from the centre of the Sun to the Earth’s equator. At the precise moment this happens the Sun reaches 0˚ Aires at the spring equinox in the northern hemisphere, or 0˚ Libra at the Autumn equinox (in the northern hemisphere). The phenomenon of the precession of the equinoxes has been known since ancient times, and it has been mathematically determined by modern astronomers that every year when the Sun reaches 0˚ Aires at the spring equinox, it does not do so in the exact same space as it did the year before, and when the position of the Earth is taken in reference to some fixed star (the Hindu astronomers selected the star Revati to mark the beginning of Aires) it is found to be close to 50 arc seconds of space further west. Modern astronomy has determined that the present rate of precession is 50.1 arc seconds per year, which means it takes 72 years for the equinoctial points to precess 1˚. At that rate it would take 25,920 years for the Spring Equinox to make one whole circle of the Zodiac. Yet the great sages of ancient India, who were gifted astronomers say that the cycle of precession actually takes 24,000 years, because the cycle of precession is sometimes slightly faster than at other times. Notably the astronomer Hipparchus (146BC) gave the rate of precession in his time as 50 + 2/3 arc seconds per year, which is somewhat faster than at present. Additionally the rate of precession has been accelerating over at least the last hundred yearsº The popular theory that precession is caused by a wobble on the Earth’s axis, although most often disseminated as fact, is still actually only a theory. Copernicus first put forward the idea of a “wobbling” spin axis in 1543 in his treatise De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) a seminal work on heliocentric theory, but he never said it was due to local forces. It was Sir Isaac Newton, who had just developed his theories of gravity who thought that if the Earth did wobble it must be due to the mass of the Sun and the Moon, the only bodies considered close enough or large enough to have such an effect. But Newton’s equations never did match observed precession rates. They were later revised by Jean-le-Rond D’Alembert, and have been revised numerous times since. In short the idea that the Earth’s wobble is the cause of precession is more tenuous than we commonly think.
Sri Yukteswar, in his 1894 book The Holy Science: “We learn from Oriental astronomy that moons revolve around their planets, and planets with their moons round the sun; and the sun with its planets and their moons, takes some star for its dual and revolves around it in about 24,000 years of our earth – a celestial phenomenon which causes the backward movement of the equinoctial points around the zodiac”. The precession of the equinoxes is therefore significantly related to the cycle of the yugas and should be taken into consideration together. Western astrologers place significance on the position of the Vernal Equinox in the Zodiac and thus call the present era the Age of Pisces, but ancient astrologers looked to the Autumn Equinox as more important, which would put our current time as the Age of Virgo. Whichever way we decide to look upon it however, we can be reminded that the zodiac operates as a cycle of natural polarity pairs, where both Pisces and Virgo characteristics are active.
º The rate was under 50.255 arc seconds before 1900 and is currently 50.29 arc seconds per year (taken from 1900-1980 The American Ephemeris and Nautical Almanac; 1981-2002 The Astronomical Almanac - United States Naval Observatory