Transcript: Over 2,000 pulsars are now known. Pulsars are found by large radio telescopes that can sensitively search through the Milky Way galaxy for these rare stellar remnants. The telescopes also tune through various frequencies to detect all the different periods of a pulsing neutron star. The periods range from around a millisecond to a few seconds. Imagine that there are stars that rotate hundreds or even a thousand times in a second. Pulsars are just the subset of neutron stars with strong radio emission that’s beamed towards the Earth. In 1968 the theorist Thomas Gold showed how charged particles trapped in magnetic fields on the surface of a spinning neutron star could produce focused radio waves. Think of a pulsar as a little lighthouse with a beam of radio emission emerging from a hot spot on the surface. As the pulsar spins, the beam of radio waves passes across the surface of the Earth, and we see a pulsar. But since many neutron stars either don’t have hot spots or have pulses of radio emission that do not cross the Earth, we do not see all the neutron stars; we only see the subset with radio pulses pointed at our direction.