User:L3erdnik/sandbox

The unusual 3:2 resonant tidal locking is stabilized by the variance along the Mercury's orbit of the tidal force acting on a permanent dipole component of Mercury's mass distribution. When the orbit of a planet is circular, the only resonance stabilized by such force is 1:1, when tidal force that stretches the planet radially (along the line sun-planet) exerting a torque that aligns planet's axis of least inertia ("the longest axis") so to pass through the sun. However, with noticeable eccentricity that the Mercury's orbit has, the tidal force becomes stronger at perihelion and thus stabilizes resonances like 3:2, when the planet points its axis of least inertia roughly at the sun during the stronger tidal force around the perihelion.