Libration of the moon


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Related to Libration of the moon: Libration in latitude, Lunar libration
any one of those small periodical changes in the position of the moon's surface relatively to the earth, in consequence of which narrow portions at opposite limbs become visible or invisible alternately. It receives different names according to the manner in which it takes place; as: (a) Libration in longitude, that which, depending on the place of the moon in its elliptic orbit, causes small portions near the eastern and western borders alternately to appear and disappear each month. (b) Libration in latitude, that which depends on the varying position of the moon's axis in respect to the spectator, causing the alternate appearance and disappearance of either pole. (c) Diurnal or parallactic libration, that which brings into view on the upper limb, at rising and setting, some parts not in the average visible hemisphere.

See also: Libration

References in periodicals archive ?
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.
Because the total libration of the Moon depends on a combination of all of these physical factors (and others), calculating the libration zone was quite difficult before the advent of electronic computers.
Joseph Louis Lagrange died; an Italian-French astronomer and mathematician; made investigations into the libration of the Moon, the planetary theory, and the theory of Jupiter's satellites.