Geography

Greek mathematician and astronomer who created the theory of proportion and the method of exhaustion preserved in Euclid's Elements, and the first geometrical model of planetary motion.

geometry, theory of proportion, astronomy

Hellenistic scholar and head of the Library of Alexandria who measured the circumference of the Earth, drew a gridded world map, founded scientific chronology and gave his name to the prime-number sieve.

geography, geodesy, number theory

Greek astronomer of the second century BC who built the first known chord table, fitted geometric models of the Sun and Moon to observations, bounded the Moon's distance, compiled a star catalogue and discovered the precession of the equinoxes.

astronomy, trigonometry, geography

Alexandrian astronomer of the second century AD whose Almagest set out the geocentric models, chord table and star catalogue that governed astronomy until Copernicus and Kepler.

astronomy, trigonometry, geography

Baghdad scholar whose book on al-jabr founded algebra as the systematic solution of equations, whose arithmetic carried Indian decimal numerals and his name (algorithm) to Europe, and who compiled the Zij al-Sindhind and a coordinate geography of the world.

algebra, arithmetic, astronomy