Kepler's (Three) Laws of Planetary Motion
1. Each planet moves in an elliptical orbit with the Sun at one focus.

2. The line from the Sun to any planet sweeps out equal areas in equal time intervals.

3. For each planet, the square of the period is proportional to the cube of the average radius.

Newton's Law of Universal Gravitation

Fg = G M m/d2

Satellite Orbits

Fg = Fc

Low-Earth Orbit

Fg = m g

Geosynchronous Orbit 

T = 24 h



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(C) 2003, Doug Davis; all rights reserved