Pulsar Stars
A Pulsar is a type of star which seem to emit bursts of electromagnetic radiation (or pulses) at a fairly regular interval. All Pulsars are neutron stars, which means that they are the left-overs of a massive star that has undergone supernova or has collapsed onto itself from its own mass. In addition to being super dense, what separates Pulsars from other star types is that they rotate. This rotation period is what causes us to see them as pulsing beacons, much like a lighthouse. We are only able to see the beam of radiation that they send out when that beam is rotated towards the Earth.
Pulsars were first discovered in 1967, by a female Ph. D student at Cambridge named Jocelyn Bell. She noticed a regular burst of energy in a part of the Crab Nebula when using the observatory's radio telescope. At first, she and her supervisor, Doctor Anthony Hewish, were completely unable to guess what was causing the energy burst, so they named the event "LGM 1" for "Little Green Man," jokingly pretending that it was caused by an extra-terrestrial civilization. However, neither of them seriously believed that this was the case.
Doctor Hewish would be awarded the Nobel Prize in Physics in 1974, but controversially Jocelyn Bell was not named in it.
Pulsars have had many practical applications in the study of our Universe, and have helped to confirm Einstein's theory of General Relativity and the discovery of extra-solar planetary systems. However, despite their great use, there is still much that scientists do not understand about them.