Pulsar

Pulsars are neutron stars that spin rapidly and produce a large amount of electromagnetic radiation along a narrow beam. They were discovered for the first time in 1967. They are spherical compact objects, with the size of a large city but with mass higher than that of the Sun.
Pulsars are used by scientists study extreme states of matter, search for planets beyond the Earth’s solar system and measure cosmic distances. It could help researchers find gravitational waves, which could point the way to energetic cosmic events like collision between massive black holes.