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physical phenomena > process > physical process > motion > rotation

rotation
subject			fact

rotation	has definition Of a single body in space: spinning on an axis. Of a planetary system, rotation is generally planar in relation to the parent star.
	is a kind of motion
physical process	has domain physics

Kinds of rotation :

• differential rotation (2 kinds, 9 facts) - Of a stellar cluster or galaxy, the "orbiting" of stars nearer the center faster than those at the edge. Of a single body (such as the Sun or a gaseous planet), the axial rotation of equatorial latitudes faster than polar latitudes., As an object rotates, different parts of it may move at different rates. The Galaxy rotates differentially.
• libration (4 facts) - The "turning" of the Moon so that although the same face is presented to Earth at all times, the overall surface of the Moon visible is 59% of the total. Libration is described as latitudinal, longitudinal and diurnal., Any of several oscillations in the apparent aspect of the Moon as seen from Earth, which, when combined, enable Earth-based observers over a period of time to see altogether about 59 percent of the Moon's surface. Physical librations are angular motions about the center of mass due to gravitational torques on the Moon. Optical librations are the apparent rotations of the Moon, caused by our observing it from somewhat different directions at different times., 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.
• synchronous rotation (3 facts) - Rotation whose period is equal to the orbital period.