Astronomy   View all facts   Glossary   Help

physical phenomena > process > physical process > motion > rotation > libration

libration comparison table

Subject	is a kind of	has definition
rotation	motion	Of a single body in space: spinning on an axis. Of a planetary system, rotation is generally planar in relation to the parent star.
libration	rotation	Variations in the orientation of the Moon's surface with respect to an observer on the Earth. Physical librations are due to variations in the rate at which the Moon rotates on its axis. The much larger optical librations are due to variations in the rate of the Moon's orbital motion, the obliquity of the Moon's equator to its orbital plane, and the diurnal changes of geometric perspective of an observer on the Earth's surface.

Next rotation: synchronous rotation    Up: rotation    Previous rotation: differential rotation