geocentric universe model
uniform circular motion (Aristotle, Ptolemy)
Aristotle
first principle
Ptolemy
retrograde motion, epicycle
heliocentric universe model
Copernicus, Brahe, Kepler, Galileo
Copernicus
paradigm
Tycho Brahe
parallax
Johannes Kepler
empirical, ellipse, semi-major axis, eccentricity
Galileo Galilei
telescope, imperfect, moons, crescent