While a planet P rotates in a circle about its sun, a moon M rotates in a circle about the planet, and both motions are in a plane. Let's call the distance between M and P one {lunar unit}. Suppose the distance of P from the sun is

lunar units; the planet makes one revolution about the sun every 3 years, and the moon makes one rotation about the planet every 0.11111111111 years. Choosing coordinates centered at the sun, so that, at time t=0 the planet is at

and the moon is at

, then the location of the moon at time t, where t is measured in years, is

where