AST101H1 Lecture 6: AST101 Lecture 6: Astronomy Before Copernicus
11 Oct 2018
School
Department
Course
23
AST101H1 Full Course Notes
Verified Note
23 documents
Document Summary
Stars, sun, moon rise and set every day. Earth does not feel like it"s moving. Planets move from night to night relative to stars. Planets do not follow a uniform pattern relative to stars. They appear to turn around relative to stars. This turn around is called retrograde motion. Egocentric model: you are at centre of universe. Apparent motion of planets are because inner planets rotate faster than outer planets. Makes extremely precise measurements of motion of mars. From this data, models of time clearly had problems. As earth moves around sun, position of nearby stars changes compared to distant ones. Conclusion: either earth is fixed, or stars are distant. Was concerned with inaccuracy of current models for theological reasons. 1st law: planets orbit sun in an elliptical pattern, with sun at one focus. 2nd law: planets trace out equal area in equal time.
