Cassini's Laws

Cassini's Laws (1693) deal with the motion of the Moon. The following describes the meaning of these three laws.

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The first law states that the Moon has 1:1 orbital resonance. This means that the rotation / orbit of the Moon is such that the same face is always facing the Earth.

Related Topics:
Orbital resonance - Rotation - Orbit - Earth

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The second law states that the Moon's rotational axis maintains the same angle of inclination from the ecliptic plane. In which case the Moon's axis forms a cone and this cone intersects the ecliptic plane as a circle.

Related Topics:
Inclination - Ecliptic plane

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The third law states that a plane formed from a normal to the ecliptic plane and a normal to the Moon's orbital plane will contain the Moon's rotational axis.

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