Ptolemy
Greek astronomer and geographer, who worked in the great library in Alexandria. Considered the greatest astronomer of late antiquity, his book known as Almagest ("the greatest') is the most important compendium of astronomy produced until the 16th-c. His system, an Earth-centered universe (the Ptolemaic system), held sway until dislodged by Copernicus. He also compiled a Geographia, containing a catalogue of places with latitude and longitude, wrote on the musical scale and chronology, and constructed several maps, including a map of the world.
