Ptolemy lived in Egypt, under the Roman Empire.  In his lifetime, he was the first professional Astronomer who published a textbook (Almagest) complied of observations made by him and his predecors.  One of his own observations was planetary motion.  He accurately predicted it and refined the geocentric model which remained accurate until 1543.  Not only was he an esteemed astronomer, but a mathematician, geographer, poet, and astrologer as well. Ptolemy is a Greek name. It occurs once in Greek mythology, and was common among the Macedonian upper class at the time of Alexander the Great, and there were several among Alexander's army, one of whom in 323 BC made himself King of Egypt.  The crater,"Ptolemaeus" on both the moon and mars are named after him.