Cassini's Laws
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Cassini's Laws (1693) deal with the motion of the Moon.
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.
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.
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.
[edit] References
- Cassini Laws -- from Eric Weisstein's World of Physics
- Eckhardt, Donald H. (1981). "Theory of the Libration of the Moon". The Moon And the Planets 25: 3–49.