libration

English

WOTD – 14 August 2010

The libration of the Moon over a single lunar month.

Etymology

From (deprecated template usage) [etyl] Latin lībrātiō (“a hurling, swinging”), from lībrō (“poise, cause to swing”).

Pronunciation

• IPA^(key): /laɪˈbɹeɪ.ʃən/

• Audio (US):

  (file)

Noun

libration (countable and uncountable, plural librations)

1. The act of librating.
2. (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.
3. (by extension) A similar rotational or orbital characteristic of some other celestial body.
4. (chemistry) A vibrational degree of freedom whereby a group of atoms partly rotates back and forth, similar to the Moon's motion.

Related terms

• librate

Translations

act of libration

• Afrikaans: librasie (af)
• Armenian: ճոճում (hy) (čočum), երերում (hy) (ererum), տատանում (hy) (tatanum)
• (deprecated template usage) {{trans-mid}}
• Finnish: huojunta (fi)
• Russian: качание (ru) (kačanije)

astronomy: apparent wobble of the moon

• Armenian: լիբրացիա (hy) (libracʻia), ճոճք (hy) (čočkʻ)
• Finnish: huojunta (fi), libraatio
• Icelandic: tunglvik n
• (deprecated template usage) {{trans-mid}}
• Japanese: 秤動 (ひょうどう, hyōdō)
• Korean: 칭동 (chingdong)
• Russian: либра́ция (ru) (librácija)

astronomy: similar characteristic of another celesial object

• Armenian: լիբրացիա (hy) (libracʻia), ճոճք (hy) (čočkʻ)
• Finnish: huojunta (fi), libraatio
• (deprecated template usage) {{trans-mid}}
• Korean: 칭동 (chingdong)
• Russian: либра́ция (ru) (librácija)