出典:Wiktionary
libration (countable かつ uncountable, 複数形 librations)
出典:Wikipedia
出典:『Wikipedia』 (2011/03/15 22:27 UTC 版)
In astronomy, libration is an 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 Jupiter.