AS101 Lecture 2: Intro to the Solar System
Document Summary
Focus around a single star or star system and the objects that orbit around it. Sun, moon, and five known planets are arranged in concentric spheres around the earth. Stars exist in the outermost sphere called celestial sphere. Provided means of predicting the dates and times when celestial bodies rose and set. Problems: bulky requires 55 inner spheres to account for observed motion doesn"t explain retrograde motion (reverse motion of some planets). Believed sun was fixed and earth traveled around it. He constructed the heliocentric model for the solar system. Believed that the orbits of the planets were circular. Problem: circular orbits could not accurately predict motion of planets without adding smaller circles called epicycles. Took careful observations of all celestial bodies, particularly mars, that were far more precise than any previously made. More open to new ideas, suggested that the planetary orbits were elliptical rather than circular. Correctly predicted the location of the planets in our solar system.
