Cassini's laws

[1] Refinements of these laws to include physical librations have been made,[1] and they have been generalized to treat other satellites and planets.

[2][3][4] In the case of the Moon, its rotational axis always points some 1.5 degrees away from the North ecliptic pole.

Therefore, both the normal to the orbital plane and the Moon's rotational axis precess around the ecliptic pole with the same period.

It turns out that the spin axis traces out loops on the unit sphere that rotates at the speed of the orbital precession (so that the orbit normal and the normal to the Laplace plane are fixed points in the sphere).

If an object flexes and dissipates kinetic energy, then these solutions are not exact and the system will slowly evolve and approach a stable Cassini state.

Orbital inclination and rotation. When the Moon is 5.14° north of the ecliptic, its north pole is tilted 6.68° away from the Earth. The orientation of the plane containing the vectors normal to the orbits and the Moon's rotational axis rotates 360° with a period of about 18.6 years, whereas the Earth's axis precesses with a period of around 26,000 years, so the line-up of this illustration (a major lunar standstill ) occurs only once every 18.6 years.