Lecture 5 E. Kepler's Laws Match Tycho's Data
- Kepler's First Law: All orbits are ellipses, some very near to circles
- Kepler found
Mars' orbit* to be an
ellipse*
- eccentric ellipses are not circles -- Greek "Perfection of Circles" is out!
- Kepler's Second Law: Line from Sun to planet sweeps out constant area per unit time
constant area per unit time*
- Kepler's Third Law: (time to complete one orbit)2 = (semimajor axis of
orbit)3
- first equation: don't memorize it, but be able to use it!
- you'll do a homework problem to verify this law