Libration in Longitude -- from Eric Weisstein's World of Physics

The appearance that a point on the surface of the Moon Eric Weisstein's World of Astronomy has displaced by a longitude , caused by the eccentricity of the moon's orbit (where M is the mean anomaly and v is the true anomaly). The maximum libration in longitude occurs when

But the mean motion n is given by

and the specific angular momentum by

so

and

where a is the mean orbital radius and e is the eccentricity.

Diurnal Libration, Libration in Latitude, Physical Libration