Biography of Ptolemy: History, Facts & Contributions

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  • 0:00 Who Was Ptolemy?
  • 0:47 Ptolemy and Astronomy
  • 1:47 Ptolemy and Geography
  • 2:26 Ptolemy and Astrology
  • 2:57 Ptolemy and Other Subjects
  • 3:36 Lesson Summary
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Lesson Transcript
Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

Explore the life and accomplishments of the Greek-Egyptian writer, mathematician, and astronomer Ptolemy. Then, test your understanding about the ancient world and early sciences.

Who Was Ptolemy?

The term, classical civilization refers to a society seen as the foundation of a culture. For many scholars, the ancient Greeks and Romans are the classical civilization, or the originators, of Western culture, and for many years, Western scholars have looked to the people of this time and place for advice and knowledge.

One of those ancient, or classical, intellectuals was Ptolemy, a Greek-Egyptian mathematician, astronomer, geographer, astrologer, and poet who lived from roughly C.E. 90-168. He resided and worked in Alexandria, a major city in Egypt founded by Alexander the Great that was part of the Roman Empire. His full name, Claudius Ptolemy, was a Roman name, indicating that he held rights as a Roman citizen. Little is known about his early life, but he was clearly well educated.

Ptolemy and Astronomy

Ptolemy's book Almagest, written in Greek, is the only surviving ancient work on astronomy. Ptolemy based his astronomic calculations on observations by ancient astronomers from the previous 800 years. None of those works survive, but the Almagest describes many of their studies. In the book, Ptolemy presents mathematical techniques for predicting the movements of stars and planets in easy-to-read charts. He also included a list of 48 constellations recognized by the Greeks and Romans.

Ptolemy wrote another book on astronomy, Planetary Hypotheses, in which he used the mathematical models of planetary motion to predict the size of the universe. Ptolemy used the radius of the Earth as the base unit of measurement and said the sun was 1,210 Earth-radii away while the universe was 20,000 times the radius of the Earth. Later, Ptolemy presented all of the basic formulas and data for predicting the positions of the sun, moon, and planets, as well as eclipses, in another book called Handy Tables.

Ptolemy and Geography

Ptolemy was also a master of geography. His book, Geographia featured a compilation of all major works on geography in the ancient world. Again, this is very helpful to modern scholars, since most of those works have disappeared. Instead of dividing the Earth into latitudes, a convention used since the first century C.E., Ptolemy divided the Earth into a grid based on 'climata,' the length of the day on the summer solstice. The Geographia provided instructions for accurate map-making and presented several maps of the Greek and Roman world. As these maps stretch into China, they become less accurate; Ptolemy admitted he had limited knowledge about the Far East.

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