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"Astrology is to Astronomy what Alchemy is to Chemistry."

Andrew Harmsworth

Astrology

The origins of astrology are lost in pre-history. The basic objective is simple, even if misguided: to find out the future. By 1000 BC astrology had spread to Egypt. The Egyptians invented a 12-month calendar, and introduced the study of "fixed stars" that later became the basis of the signs of the Zodiac.

The Zodiac

More important contributions were then made by the Greeks. They divided the heavens into 12 segments, through which the Sun and planets were seen to move against the background of stars. These segments (called houses) were eventually named by linking up the main stars in them, and giving them human and animal identities - the crab, bull, etc. Click for more.

Star Sign in Error!

Your star sign is based on the very simple notion that the Sun appears to move through the twelve constellations of the Zodiac over the course of 1 year. At the time you are born, it is in your star sign. This is very simple, and one would expect it not to be a mistake.

The author was born on April 11th 1974. According to every newspaper's horoscope column across the globe, I am an Aries. However, careful observational astronomy, or the use of an accurate electronic Orrery, proves this to be sadly untrue. The diagram below shows I'm a Pisces, not Aries!
The image (taken from ORRERY, by Photodesk) clearly shows the Sun (from our viewpoint on Earth - the white line is our orbit. Note the moon lurking nearby!) in the constellation of Pisces, not Aries! Similar cases are true for all other star signs - it is not hard to imagine that a month later, the Sun would be in Acquarius - yet this would be for those who are supposedly Pisces!

Why is Your Star Sign Wrong?

The reason for this is Astronomical, not Astrological. The Earth does not just orbit the Sun in a simple circle; far from it. Its orbit is elliptical. This in itself doesn't alter the star signs, nor does it affect the seasons [info coming soon].

The earth's axis is tilted from the vertical¹ by 23·5°. Due to the gravitational pull by the Sun and Moon, the direction in which the axis points slowly precesses over 26,000 years.

Think of the earth as a giant spinning top, or gyroscope, like you had as a child. The faster it spins, or the heavier it is, the more difficult it is to change the direction in which its axis points. However, its weight tends to make it fall over, so it precesses: [dig1]

... to be continued...