Illustration entitled 'Pulsar'. A pulsar is a regularly 'pulsing' source of radiation, almost certainly originating as a neutron star. The core is rotating, and the pulse effect is seen when one of the two 'beams' of radiation sweep across the observer. An easy analogy is that of an observer seeing the apparently flashing light from a lighthouse. The pulsar's radiation is a synchrotron emission, arising from electrons moving within its intense magnetic field. Pulsars may be observed at radio, visible and X-ray wavelengths. Periods of rotation in observed pulsars vary from 0.033 seconds to 4 seconds.