Tropical zodiac

The zodiac is an area of the sky centred upon the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets also remain close to the ecliptic, within the belt of the zodiac, which extends 8–9° north or south of the ecliptic, as measured in celestial latitude. In Western astrology and (formerly) astronomy, the zodiac is divided into twelve signs, each occupying 30° of celestial longitude. Because the signs are regular, they do not correspond exactly to the boundaries of the constellations after which they are named.

The twelve astrological signs form a celestial coordinate system, or more specifically an ecliptic coordinate system, which takes the ecliptic as the origin of latitude and the Sun's position at vernal equinox as the origin of longitude.

The English word derives from , the Latinized form of the Ancient Greek zōidiakòs kýklos ( ), meaning "circle of little animals". Zōidion () is the diminutive of zōion (, "animal"). The name reflects the prominence of animals (and mythological hybrids) among the twelve signs.

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