If you had been able to take a picture of the skies at the moment of your birth, that photograph would be your horoscope. Lacking such a snapshot, it is still possible to recreate the picture—and this is at the basis of the astrologer’s art. In other words, your horoscope is a representation of the skies with the planets in the exact positions they occupied at the time you were bora.
The year of birth tells an astrologer the positions of the distant, slow-moving planets Jupiter, Saturn, Uranus, Neptune, and Pluto. The month of birth indicates the Sun sign, or birth sign as it is commonly called, as well as indicating the positions of the rapidly moving planets Venus, Mercury, and Mars. The day and time of birth will locate the position of our Moon. And the moment—the exact hour and minute—of birth determines the houses through what is called the Ascendant, or Rising sign.
With this information the astrologer consults various tables to calculate the specific positions of the Sun, Moon, and other planets relative to your birthplace at the moment you were born. Then he or she locates them by means of the Zodiac.
The Zodiac is a band of stars (constellations) in the skies, centered on the Sun’s apparent path around the Earth, and is divided into twelve equal segments, or signs. What we are actually dividing up is the Earth’s path around the Sun. But from our point of view here on Earth, it seems as if the Sun is making a great circle around our planet in the sky, so we say it is the Sun’s apparent path. This twelvefold division, the Zodiac, is a reference system for the astrologer. At any given moment the planets—and in astrology both the Sun and Moon are considered to be planets—can all be located at a specific point along this path.
Now where in all this are you, the subject of the horoscope? Your character is largely determined by the sign the Sun is in. So that is where the astrologer looks first in your horoscope, at your Sun sign.