A rotation is a circular movement of an object around a center (or point) of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation about an external point, e.g. the Earth about the Sun, is called a revolution or orbital revolution, typically when it is produced by gravity.

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Famous quotes containing the word rotation:

    The lazy manage to keep up with the earth’s rotation just as well as the industrious.
    Mason Cooley (b. 1927)