<P> A rotation is a circular movement of an object around a center ( or point ) of rotation . A three - dimensional object can always be rotated around an infinite number of imaginary lines called rotation axes ( / ˈæksiːz / AK - seez ) . If the axis passes through the body 's 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 . The axis is called a pole . </P>
an object that moves around an external axis is said to be
revolution or orbital revolution