Ptolemy introduced the idea that the Earth was the center of the universe and that the Sun, Moon ,and all other celestial bodies reveolved around it. Ptolemy's major Astroligical text was titled Tetrabiblos Syntaxis which means four books. He recorded one-thousand stars and three-hundred were newly found. He also wrote the Almagest which was an astronomical treatise that is text on the ancient view of Astronomy. He calculated the circumfrence of the Earth and belieeved that the Earth was indeed round.