Aristotle

(384-322 BCE)

-Aristotle argued that the universe is spherical and finite.

-To prove that the earth is a sphere, he produced the argument that all earthly substances move towards the center, and thus would eventually have to form a sphere. http://www.perseus.tufts.edu/GreekScience/Students/Tom/AristotleAstro.html

Hipparchus

(190-120 BC)

-He made an early contribution to trigonometry producing a table of chords, an early example of a trigonometric table; indeed some historians go so far as to say that trigonometry was invented by him.

http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Hipparchus.html

Ptolemy

(85-165 BC)

-Ptolemy used geometric models to predict the positions of the sun, moon, and planets, using combinations of circular motion known as epicycles.

http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Ptolemy.html