Rotating Pulsar animation courtesy                                                                                                                                                   Parkes 64m radio telescope
of Matthew Bailes, Swinburne
 
 
 

A pulsar is a highly magnetised rotating neutron star which emits radiation along its magnetic poles. If it is oriented correctly with respect to the earth then we "see" it pulse on and off as it's radiation beam sweeps over us. This is similar to the rotation of a lighthouse ( see figure above), except that a Pulsar's emissions are brightest in the radio spectrum and therefore must be observed through a radio telescope.

It is believed that pulsars are formed when massive, short-lived stars explode as supernova, since young pulsars are often found amoung supernova remnants , however, the exact nature and origin of Pulsars remains a mystery.   .   .   .
 

Chart record of individual pulses from one of the first pulsars discovered, PSR  B 0329+54. The pulses occur at regular intervals of about 0.714 s.