Differential rotation
Differential rotation is seen if parts of a rotating object move with different
angular velocity. (to put it short and non-scientific, parts at different distances from the rotation axis make a different number of rounds at a given time interval). This indicates that the object is not solid. In fluid objects, such as accretion disks this leads to shearing. Usually
galaxies and protostars show also differential rotation. Also
Sun,
Jupiter and
Saturn show differential rotation.