Using NASA paper to accurately model orbital paths in Swift. Used in the iOS/iPad app SolarScene.
Much of the documentation is in the playground itself in comments.
Source of inspiration and resources: https://github.com/TimeMagazine/node-astronomy -
"Given the major orbital elements, calculate the three-dimensional orbits for planets and comets. The Jet Propulsion Labratory has a lucid explanation of approximating planetary positions here: http://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf. ... DATA Planets: http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt"
Download the playground, and to view the Scenekit Scene, open the assistant editor and checkout the timeline. Play with the timer to change the orbit speeds. The link directly above has information for adding even more planets.