| Term: | Libration |
| Definition: |
Small oscillations of a celestial body about its mean position. The term is used mainly to mean the Moon's libration caused by the apparent wobble of the Moon as it orbits the Earth. The Moon always keeps the same side toward the Earth, but due to libration, 59% of the Moon's surface can be seen over a period of time. This results from three kinds of libration working in combination: libration in longitude, libration in latitude, and diurnal libration. |