Clairaut's Theorem (Gravity)

Clairaut's theorem characterizes the surface gravity on a viscous rotating ellipsoid held in hydrostatic equilibrium by the combined action of its own gravitational field and centrifugal force. Alexis Claude Clairaut published it in 1743 in a treatise that synthesized physical and geodetic evidence that the Earth is an oblate ellipsoid, and it was initially used to relate the gravity at any point on the Earth's surface to that point's position, allowing the planet's flattening to be calculated from gravity measurements taken at different latitudes; today it has largely been superseded by the Somigliana equation.