pulsar

A pulsar is a rapidly spinning, blinking neutron star. It gives off sharp regular pulses of radio waves at a rate of up to one thousand times per second. "Pulsar" is the abbreviated form of "pulsating radio source." When the first pulsar was discovered, it was almost mistaken for communication attempts by an alien civilization.

A neutron star is the extremely dense, compact, neutron-filled remains of a massive star a star with at least 1.4 times the mass of the sun. When such a star reaches the end of its lifetime, it undergoes a supernova explosion. It then folds in on itself, becoming so compact that it measures only about 12 miles (20 kilometers) across. In the process, the protons and electrons in the star become converted into neutrons.