Constellation Guide

How did the constellations get their names?

Most constellation names are Latin in origin, dating from the Roman empire, but their meanings often originated in the distant past of human civilization. Scorpius, for instance, was given its name from the Latin word for scorpion, but ancient Egyptian hieroglyphs from before 3000 B.C. refer to the star group as "Ip," the scorpion king. Orion, the hunter, bears a Greek name, but had been seen as a hunter-hero figure since the times of ancient Babylon.

Of course, many of the constellation names are more modern -- Telescopium, the telescope, being a rather obvious newcomer. In fact, by the 19th century the night sky had become crowded with overlapping and often contradictory constellation boundaries and names as different schools of astronomy prepared their own versions of star maps. To clear up the confusion, names and boundaries were "officially" assigned to 88 constellations by the International Astronomical Union in 1930, providing complete coverage of the entire sky.

How do the signs of the zodiac relate to astronomy?

Though many people start their days by checking their horoscope in the newspaper, the 12 constellations of the zodiac are no more important to astronomers than the other 76 constellations.

The significance of the zodiac stems from the fact that the ecliptic -- the narrow path on the sky that the Sun, Moon, and planets appear to follow -- runs directly through these star groupings. Since ancient times, the Sun, Moon, and planets have been known as special astronomical objects -- they "wander" through the background stars of the zodiac, which remain fixed with respect to each other. It was reasoned that these zodiacal constellations must be special to make up this path, and the relative positions of the "wandering stars" within them bore great importance.

True scientific astronomy has its roots in the attempts of ancient astrologers to predict future occurrences of, for instance, imperial Jupiter and the blood-red planet Mars meeting within the charging bull of Taurus -- a potentially powerful omen for those who believed the planets represented the gods themselves.