Planisphere celeste septentrional ; Planisphere celeste meridional /
Available also through the Library of Congress Web site as a raster image.
Approximately 2000 B.C., Babylonian astrologers believed that the Sun, Moon, and the five planets known at that time (Jupiter, Mars, Mercury, Saturn, and Venus) possessed distinct powers. Mars, for example, appeared to be red and was associated with aggression and war. Astrology was inherited by the Greeks from Babylonians around the 4th century B.C.Through the studies of Plato, Aristotle, and others, astrology came to be regarded as a science. It was embraced by the Romans and the Arabs. The zodiac (which is derived from the Greek word meaning "circle of animals") is believed to have developed in ancient Egypt and later adopted by the Babylonians. Early astrologers knew it took 12 lunar cycles (i.e., months) for the sun to return to its original position. They then identified 12 constellations that they observed were linked to the progression of the seasons and assigned them names of certain animals and persons (in Babylonia, for example, the rainy season was found to occur when the Sun was in a particular constellation which was then named Aquarius, or water bearer). Each of these four groups is inscribed in its own quadrant, or group of "houses," on a circle. The division of the 12 houses is based on Earth's daily rotation and relates to such circumstances as relationships, finances, travel, etc. The division of the 12 signs of the zodiac is based on the earth's year-long rotation around the Sun and relates to character traits and areas of life.