Ptolemy's work in ancient times laid the foundations for our modern understanding of the universe. Now in a digestible, pocket format for the modern reader. Ptolemy's great astronomical work, which we know as The Almagest, brought together the ideas of Greek Antiquity, based on Aristotle some 400 years earlier, that the sun and planets revolved around the earth. This geocentric view which was inherited by Byzantine and Islamic scholars until Copernicus' observations 1400 years later, placed the sun at the focal point of the solar system. For centuries Ptolemy's methods were sufficient to predict solar and lunar eclipses and his work was translated into Latin in the 12th century, spreading its use across western Europe. This new, accessible edition brings the learning of the past to readers of today. AUTHOR: Claudius Ptolemy (about 100 170 CE) lived in Alexandria, Egypt, part of the Roman Empire. A mathematician, geographer and astrologer, his famous book on astronomy codified the ancient view of the universe, with the sun and observable planets orbiting around the earth.