In astronomy, the zodiac or zodiac that means (wheel) animals is formally a band of the celestial sphere 18 degrees wide centered on the ecliptic, which is not fixed but shifts slightly with time on sky background. This band is divided into 12 equal parts called "zodiacal signs", with reference to the Aries point, the point of intersection between the ecliptic and the celestial Ecuador. Thus, each 12 signs comprises exactly an arc of 30 degrees longitude and ecliptic ecliptic 9 degrees latitude. The zodiacal signs are areas of the celestial sphere which are defined differently from the constellations of the same name, so that a given zodiacal sign and the constellation of the same name covering different areas of the celestial sphere are defined.
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, advancing a sector for each month of the year. Each sector contains the traditional constellation to which it owes its name. The Zodiac has a fundamental importance in Western astrology. Other cultures with astrological tradition as Chinese also give a special importance this region of the sky, but define a different zodiac.