Kepler's Construction
How Kepler constructed the trajectories of the planets and comparison with the approximation formula for almost circular orbits (earth) - for details look into the attached PDF (section KEPLER)!
Do not use the "play-button" - you will get a false impression. The second half of the orbit needs more time than the first! Use the velocity vector instead (think of the fact that it's scaled!). "Move time" manually.