What are pulsars and why do they pulse?

The answer

Pulsars are rapidly rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles. Because the magnetic axis is tilted relative to the rotation axis, these beams sweep through space like lighthouse beacons. When a beam points toward Earth, we detect a pulse. Some pulsars are so regular that they rival atomic clocks in precision. The fastest known pulsar, PSR J1748-2446ad, spins 716 times per second - its surface moves at about 24% the speed of light. They were first discovered in 1967 by Jocelyn Bell Burnell.