Small improvement - a little quicker and easier code. Click in space and the earth will go there, change the speed sliders to tell it where to move. When the earth gets close to the sun its movements become completely wrong. How it's done: ============== The key teachniques to work out movement are explained in the bouncing ball example. To work out the movement of the earth: - find out the distance to the sun, R - the force that applies to the earth is proportional to 1/(R*R) - The Vertical and Horizontal elements of that force tell you how much to change HSpeed and VSpeed.
