ASTA01H3 Lecture Notes - Lecture 1: Ellipse, Nicolaus Copernicus, Copernican Revolution
Document Summary
Aristotle believed that heavenly objects moved on circular paths at constant speed around the earth, with earth immobile at the centre of the universe. Aristotle"s philosophical system was turned into a mathematical model of the universe by. The model worked well except when it came to predicting the position of planets. As viewed from the earth, planets moved from east to west but sometimes showed retrograde motion, meaning they moved from west to east. To explain the strange paths of planets, ptolemy devised a system consisting of a number of uniformly rotating circles. The centre of epicycle orbited a circle, called deferent, centred on a point called eccentric, which was off the centre of the earth. The planets exhibited uniform motion only if viewed from another point called equant. As seen from the equant, a planet swept out equal angles in equal time intervals.
