Ptolemy was born in Sebede in 85 AD. From 127 to 15 1 year, he was one of the most important figures who conducted astronomical research in Alexandria, and he was also a master and representative of the geocentric theory that influenced human beings 1000 years. His important book, Grand Synthesis, 13, summarizes all the achievements of astronomy in the Greek era, especially the achievements of astronomers of Alexandria school, the discovery of Iba Valley and the theoretical system of geometricians such as Apolloni.
The grand synthesis theory systematically develops the theory of Iba Valley and is an encyclopedia of ancient astronomy. It uses nearly 80 circles to explain the motion of celestial bodies and draws the universe system into a logical and perfect mathematical chart. It also explains some astronomical phenomena that can reflect the movement of some celestial bodies. But it imagines the earth as the center of the universe, which fundamentally distorts the original appearance of celestial movement.
Volume 1 of Grand Synthesis briefly introduces Ptolemy's basic views on the structure of the universe and discusses the evidence that the earth is spherical. Volume 2 introduces some basic definitions and basic theories. The third volume discusses the irregular movement of the sun and the length of a year. Volume 4 discusses the theory of the moon's motion and his own important discoveries. The fifth volume discusses astronomical instruments, including parallax gauge, celestial globe, quadrant and water clock, and introduces the method of calculating the distance between the sun and the moon. The sixth volume discusses the calculation methods of solar and lunar eclipses. Volumes 7 and 8 introduce the catalogue of 1080 stars. At the end of volume 9, the theory of planetary motion is introduced. His theory was proved wrong by later generations. Ptolemy died in 165. He is the most accomplished astronomer in the west since the death of Iba Valley.