1. Ptolemy By: Kenneth Duffy

2. Introduction Ptolemy’s system known as the Ptolemaic system was used for almost a millennium and a half.

3. Birth Ptolemy was born around 87 AD, but this information is not the most accurate, because the dates from when he lived and died where never confirmed. He lived in Alexandria, Egypt for his entire life.

4. About Ptolemy “His name, Claudius Ptolemy, is of course a mixture of the Greek Egyptian 'Ptolemy' and the Roman 'Claudius'. This would indicate that he was descended from a Greek family living in Egypt and that he was a citizen of Rome, which would be as a result of a Roman emperor giving that 'reward' to one of Ptolemy's ancestors.” from about.com

5. Inventions He wrote the Almagest, which is a 13 chapter book that explained why things in astronomy happened. He extended Hipparchus star catalog from 850 stars to 1022 stars.

6. Geography Ptolemy was the first person known to draw the earth as a sphere onto a plane. His work stayed active until Christopher Columbus sailed around the world.

7. Almagest It contained the idea of a geocentric universe, where a motionless earth is the center of the universe with the sun and other planets rotating around the earth, and this became the prevailing theory around the world. Remained creditable until Copernicus suggested his heliocentric theory, which is a sun-centered universe, in 1543. Ptolemy’s system was more precise than Copernicus’s.

8. Death Ptolemy died around 150 AD. There is no hard evidence of when exactly Ptolemy was born or died.

9. Conclusions Ptolemy was a great thinker of his time, he contributed to many great ideas and concepts that helped pave the way to modern day science as we know it.

10. Work Cited: Greene, N. (n.d.). Ptolemy Biography. Retrieved 04 20, 2012, from about.com: http://space.about.com/cs/astronomerbios/a/ ptolemybio.htm Lahanas, M. (1998, 10 19). Astronomy of Ptolemy. Retrieved 04 20, 2012, from http://www.mlahanas.de/Greeks/PtolemyAstr onomy.htm