Chapter 3: Kepler’s 3 law of Motion:
-1 Law: The Planets move in ellipse (not circles)
-The planets move in elliptical orbits with the Sun at one focus.
-Nothing is at the other focus.
-The Sun-Planet distance varies during its orbits – but this is not the source of the
- A departure from insistence on perfect spheres.
-2 Law: Planets sweep out equal areas in equal time.
-Near perihelion: in any particular amount of time (such as 30 days), a planet sweeps
out an area that is short but wide
- Near Aphelion: in the same amount