Rotation of Mercury: Theoretical Analysis of the Dynamics of a Rigid Ellipsoidal Planet

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Science  18 Mar 1966:
Vol. 151, Issue 3716, pp. 1384-1385
DOI: 10.1126/science.151.3716.1384


The second-order nonlinear differential equation for the rotation of Mercury implies locked-in motion when the period is within the range where e is the eccentricity and T is the period of Mercury's orbit, the time t is measured from perihelion, and λ is a measure of the planet's disiortion. For values near 2T/3, the instantaneous period oscillates about 2T/3 with period (21λe/2)T.