In November 1967, Jocelyn Burnell(astrophysicist) and Anthony Hewish(Nobel laureate and radio astronomer) came across a source of pulses. The pulses arrived at 1.33 second intervals and contained waves in the electromagnetic spectrum. The signal was deemed to be a natural, non-man made(not ET) and non-instrumental(not produced by equipment) phenomenon by both Burnell and Hewish, yet they called it “LGM-1” where LGM stands for “Little Green Men”(extra terrestrials/Aliens). That was the moment of discovery of the pulsar.
The pulsar is a “pulsating star”, specifically a pulsating neutron star or white dwarf(after a star runs out of fuel to burn,it turns into a neutron star or white dwarf) that spins at extremely high velocities. It is highly energized, the energy can be in various forms like rotational energy, gravitational potential energy and magnetic field energy. This energy is radiated along a particular axis of the star. The radiation can be in any wavelength range in the electromagnetic spectrum and is highly periodic in nature. The time period of pulses is so accurate(unchanging) that it can be and is used as a reference clock by astronomers.
If the earth happens to be along the axis of radiation of a pulsar, it can be detected and cataloged by astronomers. The faster the pulsar spins, the faster the pulses it sends out. The pulses are radiated until all the energy in the pulsar is exhausted. At this point, the radiation stops and the pulsar “disappears from the radar” so to speak.
Pulsars are a very interesting species of stars that contain many properties that can be put to use( like clocks and landmarks in space). They contain many clues to understanding the mysteries of the universe. Even though its close to 50 years since their discovery, a lot of data concerning pulsars is yet to be found. Think about the number of times LGM-1 would have rotated since you started reading this post!