libration
Moon's apparent oscillation
Libration is a slight oscillation or wobbling motion that allows an observer to see slightly beyond what would otherwise be the visible edge of a celestial body.
The term applies most often to the moon, whose libration lets us see about 59 percent of its surface over time rather than exactly half.
Lunar libration reveals craters near the moon's edge that would otherwise remain hidden.
Unsteady side-to-side motion
- rockingOscillating on curved base
- noddingMoving head affirmatively
- swayingRhythmic lateral movement
- pendulumSuspended swinging weight
oscillation · vibration · fluctuation · undulation · bobbing · periodicity · amplitude · cycle
wobble
Unsteady side-to-side motion
pendulum · oscillation · vibration · fluctuation · undulation · bobbing · periodicity · amplitude · cycle · motion
moon
Natural planetary satellite
- orbitCurved celestial path
- wobbleUnsteady side-to-side motion
- oscillationRepeated back-and-forth movement
latitude · longitude · limb · mare · craters · perigee · apogee · tidal · synchronous · elliptical
librationrotation
Turning on an axis
spin · revolution · linear motion · translation · precession
librationstillness
Complete lack of motion
stability · rigidity · immobility · stasis