History ...

In astronomy, the zodiac (from Greek "zoon-Diak" meaning wheel animals) is a band that encircles the celestial sphere to the ecliptic and understanding that is wide enough to contain the Sun comprises 13-14 constellations.
In astrology, the zodiac is based on the division into twelve equal parts of the celestial band on which trace their paths the Sun, Moon, and planets, moving a section for each month of the year. Each sector contains the traditional constellation to which it owes its name. The Babylonians and Greeks divided this band into twelve equal parts, each of them a patch of sky for an extension of thirty degrees of arc, christened with the name of the twelve most prominent constellations they saw in each of the subdivisions. The zodiac has a fundamental importance in Western astrology. Other cultures such as Chinese astrological tradition also give particular importance to this region of the sky, although defines a different zodiac.


The relative position of the Sun with respect to the constellations of the zodiac at the time of a person's birth determines your astrological sign. The zodiac signs are determined by their position on the vernal point (Point Gamma, which is the 0 degree Aries) or intersection of the plane of the ecliptic with the plane of Ecuador Celeste, not by its position relative to the constellations, as usually given.
The constellations are groups of a few stars that man has given way to name and locate in the sky and appear to be fixed in the sky. The ecliptic is the plane in which Earth moves about the Sun, is especially important for astrology. There are the twelve constellations of the "fixed stars".