The name given to a belt of the heavens extending 8° on each side of the ecliptic, composed of twelve constellations called signs of the zodiac, which the sun traverses in the course of a year. These signs, of which six are on the N. of the ecliptic and six on the S., are, commencing with the former, named successively: Aries, the Ram; Taurus, the Bull; Gemini, the Twins; Cancer, the Crab; Leo, the Lion; Virgo, the Virgin; Libra, the Balance; Scorpio, the Scorpion; Sagittarius, the Archer; Capricornus, the Goat; Aquarius, the Water-bearer; and Pisces, the Fishes. The sun enters Aries at the spring equinox and Libra at the autumnal equinox, while the first point of Cancer marks the summer solstice, and that of Capricorn the winter. The name Zodiac is derived from the Greek zoon , an animal, and has been given to the belt because the majority of the signs are named after animals.