Every night, a pageant of Greek mythology circles overhead. Perseus flies to the rescue of Andromeda, Orion faces the charge of the snorting Bull, and the ship of the Argonauts sails in search of the Golden Fleece. Constellations are the invention of the human imagination, not of nature. They are an expression of the human desire to impress its own order upon the apparent chaos of the night sky. Modern science tells us that these twinkling points...