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.