Lesson Five : Why Do Neutron Stars Pulse?
Since the magnetic poles and spin axis of the neutron star are not aligned, the beams rotate with the neutron star and act like the beams of a lighthouse. We see this pulse of radio waves every time it passes by earth, similar to how we see the light beam from a lighthouse every time it passes by our eyes. Not surprisingly, this effect is called the lighthouse effect of pulsars. The number of times a neutron star pulses varies from once every few seconds to once every few thousandths of a seconds.Every time we see a pulse from a pulsar, we are seeing radio waves from the beam of radiation emitted from the magnetic pole of a rotating neutron star. Each pulse reprents a single pass of the beam.
A neutron star is not necessarily a pulsar, however. Imagine being exactly above the spin axis of a neutron star. The beam of radio waves would never pass by you, and you would never detect radio pulses. Consequently, we would not detect this neutron star as a pulsar.
David Moffett / PARI