The wobbling (or precession) causes the rotation axis of Pulsar PSR B1828-11 to follow a circle-like motion in time (see yellow and green axes). The motion is very much like the wobble of a top or gyroscope. As a result, we see the cone-like lighthouse beam of the radio pulsar under different angles, resulting changes in the shapes and arrival times of the radio pulses. (Image by M. Kramer)