Astrological Signs or Sunsigns (Zodiac Signs)

In astrology, the Signs of the Zodiac represent twelve equal segments or divisions of the zodiac. According to astrological theory, celestial phenomena reflect or govern human activity on the principle of "as above, so below", so that the twelve signs at the same time are held to represent twelve basic personality types or characteristic modes of expression.

In Western and Indian astrology, the twelve signs are associated with constellations, while in Chinese astrology there is no connection with constellations, as it is simply the line of the equator that is divided into twelve equal segments.

In Western and Indian astrology, the emphasis is on space, and the movement of the sun, moon and planets in the sky through each of the zodiac signs. In Chinese astrology, by contrast, the emphasis is on time, with the zodiac operating on cycles of years, months, and hours of the day. A common feature of all three traditions however, is the significance of the ascendant or rising sign, namely the zodiac sign that is rising (due to the rotation of the earth) on the eastern horizon at the moment of a person's birth.

The Zodiac

In Western, and (via Indo-Greek transmission in the 2nd and 1st centuries BC) Indian, astrology, the zodiac divides the ecliptic (the apparent path of the Sun through the heavens) into twelve astrological signs of equal length.

The Western tropical astrology starts with the first point of Aries, which is defined as the point at which the ecliptic crosses the celestial equator at the spring equinox. It is important to note that the tropical zodiac signs at this stage no longer bear any relationship to the astronomical constellations after which they were originally named, due to a phenomenon known as the precession of the equinoxes which produces a slow change of the time of year when constellations are visible in the night sky over a 25,000 year cycle.

Western sidereal astrology and Indian Indian astrology use signs which more or less coincide with the stellar constellations of the same name, although this involves adjustments to allow for the precession of the equinoxes.

Because the calendar is defined by the movement of the Earth around the Sun, and its orbit is very nearly circular, the sign in which the Sun falls on any day of the year is fairly predictable, though it will vary a little due to the effect of the extra day in leap years. These dates are given in the article that deals with each sign individually. To determine the sign in which the moon and other planets fall on any given day, it is necessary to consult an ephemeris or use an astrological computer program which will have a built-in ephemeris; these computer programs make it quick and easy to calculate the natal chart (also called horoscope) so that the astrologer can spend more time interpreting the chart rather than actually calculating it.

The "tropical" zodiacal dates (those that divide the zodiac starting with the northern hemisphere vernal equinox) are used primarily in the United States and western Europe. The "sidereal" dates (those that divide the zodiac starting with the alignment of the Sun with a distant star in Aries) are used primarily in India.