Earth, Sun and Moon

We treat 1 second as 27.5 earth days, which is the time it takes the moon to complete one rotation (returning to the same position) about the ellipse definining its orbit. The time taken for the earth to orbit the sun is set to 365.25 days. For simplicity we treat both orbits as being circular though in reality they have non-zero values of eccentricity and so are slightly elliptical.