libration

li·bra·tion

L0151500 (lī-brā′shən)n. A very slow oscillation, real or apparent, of a satellite as viewed from the larger celestial body around which it revolves.

[Latin lībrātiō, lībrātiōn-, oscillation, from lībrātus, past participle of lībrāre, to balance, from lībra, balance.]

li′brate′ (lī′brāt′) v.li·bra′tion·al adj.li′bra·to′ry (-brə-tôr′ē) adj.

libration

(laɪˈbreɪʃən) n1. the act or an instance of oscillating2. (Astronomy) a real or apparent oscillation of the moon enabling approximately 59 per cent of the surface to be visible from the earth over a period of time[C17: from Latin librātus, from librāre to balance] liˈbrational adj

li•bra•tion

(laɪˈbreɪ ʃən)

n. a real or apparent oscillatory motion, esp. of the moon. [1595–1605; < Latin lībrātiō act of leveling = lībrā(re) to level, balance, derivative of lībra pair of scales + -tiō -tion] li•bra′tion•al, adj. li′bra•to`ry (-brəˌtɔr i, -ˌtoʊr i) adj.

Thesaurus

Noun

libration - (astronomy) a real or apparent slow oscillation of a moon or satellite; "the libration of the moon"astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a wholevariation - (astronomy) any perturbation of the mean motion or orbit of a planet or satellite (especially a perturbation of the earth's moon)oscillation - the process of oscillating between states

Translations

librazione

libration

(lÿ-bray -shŏn) The means by which 59% of the Moon's surface is made visible, over a 30-year period, to the terrestrial observer despite the lunar day being of the same length as the sidereal month (see synchronous rotation). Physical libration is a real irregularity in the Moon's rotation, arising from minor distortions in shape. Geometrical librations, including diurnal librations, are apparent oscillations due to the Moon being observed from slightly different directions at different times. A geometrical libration in longitude of 6°9′ (mean value) results from the inconstancy of the Moon's orbital velocity, which follows from the eccentricity of the Moon's orbit and Kepler's second law. This libration reveals part of the eastern or western farside limbs at different times during one month. In addition the 5°9′ inclination of the Moon's orbital plane to the ecliptic, plus the 1°32′ tilt of the Moon's equator to its orbital plane, produces a monthly geometrical libration in latitude of 6°41′. This makes the Moon's north and south polar regions more readily observable during one month.

libration

[lī′brā·shən] (physics) Any oscillatory rotational motion, such as that of the moon, or of a molecule in a solid which does not have enough energy to make full rotations.

libration

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Words related to libration

noun (astronomy) a real or apparent slow oscillation of a moon or satellite

Related Words