Galileo & Newton -- Gravity & orbits
Kepler’s 3 laws were empirical
- Explained perfectly planetary motions, but ad hoc
- No explanation why planets moved in this manner
- Power of laws demonstrated by Galilean satellites:
- orbits circles (a form of ellipse), Jupiter at focus (center)
- equal areas in equal times (uniform circular motion here)
- Galileo’s data established a relationship between Period and size of the orbit: