In
astronomy, the
zodiac is a circle of twelve 30° divisions of celestial longitude that are centered 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. Historically, these twelve divisions are called
signs. Essentially, the zodiac is a
celestial coordinate system, or more specifically an
ecliptic coordinate system, which takes the ecliptic as the origin of
latitude, and the position of the sun at
vernal equinox as the origin of
longitude.