To explain, Greeks (Ptolemy) added epicycles
- To explain, Greeks (Ptolemy) added epicycles
- draw one on board for Mars f.4-12
- Beauty of perfect spheres and uniform rotation destroyed
- Still couldn’t accurately predict planetary positions in future
Copernicus -- early 16th century
- Realized motions naturally explained if Mars and Earth both orbited the Sun.
- since the Earth’s orbital velocity exceeded Mars’, retrograde motion predicted at opposition. f.4-16
- To explain daily motions of stars, sun, planets
- merely have Earth spin on it’s axis 1/day
- De Revolutionibus Orbium Coelestium -- a major scientific revolution
- cf. Thomas Kuhn’s book on this
- “revolutionary” = overturning accepted dogma