Crossword clues for libration
The Collaborative International Dictionary
Libration \Li*bra"tion\ (l[-i]*br[=a]"sh[u^]n), n. [L. libratio: cf. F. libration.]
The act or state of librating.
--Jer. Taylor.-
(Astron.) A real or apparent libratory motion, like that of a balance before coming to rest.
Libration of the moon, 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.
Wiktionary
n. 1 The act of librate. 2 (context astronomy English) The apparent wobble or variation in the visible side of the Moon that permanently faces the Earth, allowing observers on Earth to see, over a period of time, slightly more than half of the lunar surface. 3 (context by extension English) A similar rotational or orbital characteristic of some other celestial body.
WordNet
n. (astronomy) a real or apparent slow oscillation of a moon or satellite; "the libration of the moon"
Wikipedia
latitude and longitude. Also visible are the different phases, and the variation in visual size caused by the variable distance from Earth.
In astronomy, libration is a perceived oscillating motion of orbiting bodies relative to each other, notably including the motion of the Moon relative to Earth, or of trojan asteroids relative to planets. Lunar libration is distinct from the slight changes in the Moon's visual size as seen from Earth. Although this appearance can also be described as an oscillating motion, libration is caused by actual changes in the physical distance of the Moon, because of its elliptical orbit around Earth.
Libration (from the Latin verb librare "to balance, to sway"; cf. libra "scales") is a type of reciprocating motion in which an object with a nearly fixed orientation repeatedly rotates slightly back and forth. In physics and chemistry, a molecule (or other group of atoms) can undergo libration if it is subject to external forces or constraints that restrict its orientation.
For example, in liquid water, any given water molecule is attracted to neighboring molecules, so that it has a preferred orientation and cannot freely rotate. (Of course, over time, the neighboring molecules move around and the preferred orientation changes.) However, it can undergo librational motions, which are measureable in an infrared absorption spectrumand contribute to motional narrowing of other peaks, for instance the OH stretch.
Another example is a molecular crystal: Each molecular unit has a preferred orientation due to interactions with the nearby molecules, but they have librational modes corresponding to small rotations about this preferred orientation.
Usage examples of "libration".
Even taking libration into account, fully three-eighths of its surface is true dark-side and never sees the sun.
It does wobble about its mean position a bit as a result of libration, but not by anything near that much.
Far to the west the libration of the planet thrust a wall of cold air into the tropic heat of the sun.
You know the breeding ceremonies take place when libration has brought the temple into the sunlight.
It was located at the L5 libration point, a location where the gravitational forces of the Earth and Moon cancelled each other out.
A somewhat more spacious colony, Descartes, had been built at the L4 libration point 240,000 miles ahead of the moon.
The colonies had been made primarily of materials mined on the moon and transported to the libration points.
Or, belike, when they feel like a bit of amorous libration, they can do it perfectly well in their own persons without employing mortals as surrogates.
Even taking libration into account, fully three-eights of its surface is true dark-side and never sees the Sun.
Mercury, then using a gravity assist, and the extra force light sails get close to the sun, to send the ship upward on a close pass by either the other libration point or the Earth, with enough momentum to continue on up into the farther reaches of the solar system.
Soviets believe their site is just beyond the libration limit in the Cordillera chain.
During the gloaming time when he had only one eye with which to observe the heavens or peruse his earlier notes and drawings, he wrote a final brief treatise on how best to gauge the diameters of stars and the distances between celestial bodies, and also made his last astronomical discovery, regarding the librations, or rocking, of the Moon.
Without the computer to plot paths, or do librations the way things stood at present.
During the gloaming time when he had only one eye with which to observe the heavens or peruse his earlier notes and drawings, he wrote a final brief treatise on how best to gauge the diameters of stars and the distances between celestial bodies, and also made his last astronomical discovery, regarding the librations, or rocking, of the Moon.
Actually, we'll have a few hours before they drift far enough to destroy the effect, but we'll need all that time because we need to fire the engines at full power to force the tidal bulge past the libration point.