Hold down shift and press the green flag for Turbo Mode. Without Turbo mode you won't see it move. Kepler's 2nd law of planetary motion states that: A line joining a planet and the Sun sweeps out equal areas during equal intervals of time. (From Wikipedia). Edit: Featured March 2014. Thanks all for the comments! As for linking to Wikipedia, I see Wikipedia as a the best source of "agreed upon wisdom". When it comes to subjects like mathematics or physics, Wikipedia is reliable, any possible errors are corrected at once.
The differential equations used follow the Wikipedia description. r=orbitSize/(1+eccentricity cos(angle)) angularSpeed= speed*sqrt(1-eccentricity^2)/r^2 r is the distance to the sun. The 'eccentricity' is the eccentricity of the ellipse. When the eccentricity is 0, the ellipse is a circle. 'orbitSize' and 'angularSpeed' are bundles of other numbers that I don't need.
