The Zodiac

The Zodiac

• The tropical zodiac defines the vernal point (the first day of spring in the northern hemisphere) as the first degree of Aries, but the sidereal zodiac allows it to precess. Many people are confused regarding the difference between the sidereal zodiac and the tropical zodiac signs. Because of a "wobble" in the Earth's axis of rotation over a period of about 26,000 years (often called a "great year"), the rate at which the vernal equinox precesses in the heavens is approximately 0 deg, 0 min, 50.23 seconds a year, drifting by one degree every 72 years. Precession of the equinoxes thus occurs at a rate of roughly 5 arc minutes of a degree every 6 years. The tropical signs relate to the seasons and not the stars. Here is an example: a person born on, say August 28, 2002 would come to understand that his/her Sun sign was in Virgo according to Western astrology (conventional Sun sign dates August 23, to September 22, of every year), but Sun on that same calendar date of the year 2002 was in the constellation Leo (where it had been since August 10, 2002 and would remain until September 15, when it would then finally cross into Virgo).The Zodiac, or "circle of animals" is a zone or belt in space projected onto the celestial sphere through which, from our viewpoint, the planets move. A symbolic geometric construction around 15 to 18 degrees wide, it is divided into 12 signs, each of 30 degrees longitude (making 360 degrees in all), with the ecliptic, the apparent path of the Sun, as its middle line. The tropical zodiac used by most Western astrologers has its beginning at the exact moment that the Sun crosses the celestial equator and enters the zodiacal sign of Aries. Some Western astrologers use the sidereal zodiac favoured by Indian ("jyotish") astrologers, which is based more closely on actual positions of constellations in the heavens, as opposed to the tropical zodiac, which is a moveable format based on the seasons.

• The sun sign is the sign of the zodiac in which the sun is located for the native. This is the single astrological fact familiar to most people. If an event occurs at sunrise the ascendant and sun sign will be the same; other rising signs can then be estimated at approximately two-hour intervals from there.

• A cusp is the boundary between two signs or houses. For some the cusp includes a small portion of the two signs or houses under consideration.

It is worth pointing out that the sidereal signs and the tropical signs are both geometrical conventions of 30° each, whereas the zodiacal constellations are pictorial representations of mythological figures projected onto the celestial sphere based on patterns of visible star groupings, none of which occupy precisely 30° of the ecliptic. So constellations and signs are not the same, although for historical reasons they might have the same names.

It is also worth noting that some astrologers don't use the signs of the zodiac at all, focusing more instead on the astrological aspects and other features of the horoscope.

Houses

• The houses are a series of twelve divisions of the plane of the ecliptic. Astrologers have devised many systems of calculating these house divisions. In the case of the equal house system the ecliptic is divided into twelve equal houses of 30° each. The first house begins at the ascendant and the others are numbered counterclockwise from that point. The first six are therefore below the horizon, and the other six are above. The positions of these houses remains fixed relative to the native. The signs and planets all move through the twelve houses during the course of a day, and the planets move through the signs over the course of months or years.