Definition
In astronomy, the zodiac is the band of sky centered on the ecliptic, together with the constellations that lie along it. It is the strip of sky through which the Sun, Moon, and planets appear to move as seen from Earth.
In context
Because the Sun, Moon, and planets all stay close to the ecliptic, they are always found somewhere within this band. The Sun passes in front of these background constellations over the course of a year.
In astrology — a separate, interpretive tradition that astronomy does not endorse — this same band is instead divided into twelve equal signs used for chart-making.
Related ideas
The astronomical zodiac constellations are uneven in size and number, which is why the strict band the Sun crosses does not match the neat twelve equal divisions of astrology.
Related entries
Encyclopedia
Ecliptic
The Sun's apparent yearly path across the sky.
Encyclopedia
Transit
A smaller body passing across the face of a larger one.
Encyclopedia
Ascendant
In astrology, the zodiac sign rising on the eastern horizon at birth.
Encyclopedia
Star
A self-gravitating sphere of plasma powered by fusion.