libration

American  

[lahy-brey-shuhn] / laɪˈbreɪ ʃən /

noun

Astronomy.

1. a real or apparent oscillatory motion, especially of the moon.

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libration British  

/ laɪˈbreɪʃən /

noun

1. the act or an instance of oscillating

2. 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

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Other Word Forms

• librational adjective

Etymology

Origin of libration

1595–1605; < Latin lībrātiōn- (stem of lībrātiō ) a balancing. See librate, -ion

Example Sentences

Such libration could be explained in one of two ways: either Mimas had an extremely elongated core, shaped like a flattened football; or it had a global ocean below its surface.

From National Geographic

Using documentary evidence in the Ansel Adams Archive and lunar libration, a phenomenon that “affects the visibility of lunar surface features,” according to Dr. Olson, they narrowed down the possibilities.

From New York Times

His study of the moon’s libration shows that he was looking for new observations with which to solve cosmological issues.

From Literature

He was traveling north on the libration zone train, recording one of his travelogue narrations to distract himself from his worry about his new young American acquaintance, among other worries.

From The Verge

The current libration amplitude is 125°, with a period of about 660 years.

From Nature