Ptolemy
Tools:
- Sundial
- Telescope
- Maps (which he created)
Timeline:
- 85 Born in Egypt
- 127 Started working in a library in Alexandria, Egypt
- March 26, 127 First recorded astronomical observation
- 140 Algamest is published and widely accepted
- February 2, 141 Last recorded astronomical observation
- 150 Quit working in Alexandria library
- 165 Died in Alexandria, Egypt
Accolades:
- Wrote Algamest (The Mathematical Compilation) which consists of thirteen books.
- Developed the geocentric theory.
- He introduces trigonometrical methods based on the chord function.
- Ptolemy devised new geometrical proofs and theorems.
- Ptolemy wrote a popular account of his results under the title Planetary Hypothesis.
- In a book entitled Analemma he discussed methods of finding the angles need to construct a sundial.
- Ptolemy's major work Geography maps the world in longitude and latitude in eight books.
- Another work on Optics is in five books and studies color, reflection, refraction, and mirrors of various shapes.
- Ptolemy also wrote a work on astrology.
Benefits:
- His maps of Asia and Africa are said to have inspired Christopher Columbus in his westward expedition to India across the Atlantic.
- His mathematical theories were widely used for centuries.
Information:
- Ptolemy used observations made by 'Theon the mathematician', and this was almost certainly ‘Theon of Smyrn’ who almost certainly was his teacher.
- The Almagest is the earliest of Ptolemy's works and gives in detail the mathematical theory of the motions of the Sun, Moon, and planets.
- Ptolemy used geometric models to predict the positions of the sun, moon, and planets, using combinations of circular motion known as epicycle.
- Ptolemy compared his own observations of equinox with those of Hipparchus.
- Based on his observations of solstice and equinoxes, Ptolemy found the lengths of the seasons.
- He used Hipparchus’s ideas to develop a theory for motion of the sun and moon.
- He believed that the fixed stars always maintain the same positions relative to each other.
- Much of Books 7 and 8 are taken up with Ptolemy's star catalogue containing over one thousand stars.
- The final five books of the Almagest discuss planetary theory.
- The maps given by Ptolemy were quite inaccurate in many places for he could not be expected to do more than use the available data.
- Received attacks from scientists such as Brahe and Newton, saying hid findings are inaccurate.
Bibliography:
- O'Connor, J. J. and E. F. Robertson. “Claudius Ptolemy.” April 5, 2004.