AST-0009 Lecture Notes - Lecture 1: Orbital Period, Ellipse, Deferent And Epicycle
12 Mar 2016
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Document Summary
Milky way is one of about 100 billion galaxies. Astronomical numbers in the economy are really economical . Cosmogony: a theory about one"s place in the universe. Proposes earth to be at the center of the universe. Proposes sun to be at the center of the universe. Pythagorean universe (550 bc: first recorded attempt to rationalize universe, formed foundation for greek astronomy, philosophical ideas. Heavenly motions must be circular: pythagorean model. Rotates about axis in 23 hours and 56 minutes. Sun follows ecliptic path going around earth once in a year. Stars appeared to move across the sky without staying in respective constellations. Prograde motion (normal: apparent west to east motion of objects over many nights, as compared to stationary background stars. Retrograde motion: apparent east to west motion of objects over many nights as compared to the stationary background stars. Tried to create a model that would account for retrograde motion.
