physical libration

physical libration

Slight variations in the Moon's rotation on its axis that are caused by minor irregularities in shape. They amount to less than two arc minutes but allow the Moon's principal moments of inertia, and hence the distribution of mass within the Moon, to be calculated. The mean orientation of the Moon with respect to its physical librations defines the Moon's prime meridian. See also libration.
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The topics include laser altimetry and its applications in planetary science, integrating and co-registering multisource Lunar topographic data sets for synergistic use, Martian minerals and rock components from MRO CRISM hyperspectral images, Mercury's magnetic field in the MESSENGER era, determining the Lunar gravity field with data from Chan'E-1 and other missions, and the theory of the physical libration of the Moon with a liquid core.
Arthur Ernest Hodgson died; worked at the Natal Observatory; in 1908 he took a series of lunar photographs for a determination of the physical libration of the moon.

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