Astron. a slight, apparent rocking motion of the moon as seen from the earth, allowing approximately 59% of the moon's surface to be visible
Origin of librationClassical Latin libratio ; from libratus, past participle of librare, to weigh, balance ; from libra, a balance
A very slow oscillation, real or apparent, of a satellite as viewed from the larger celestial body around which it revolves.
Origin of librationLatin l&imacron;brati&omacron;, l&imacron;brati&omacron;n-, oscillation, from l&imacron;bratus, past participle of l&imacron;brare, to balance, from l&imacron;bra, balance.
- The act of librating.
- (astronomy) 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.
- (by extension) A similar rotational or orbital characteristic of some other celestial body.
From Latin lÄ«brÄtiÅ (“a hurling, swinging"), from lÄ«brÅ (“poise, cause to swing").