A pulsar is a star that short regular pulses of electromagnetic radiation emits (usually radio frequency, but there are also some pulsars radiate X-rays or light). Each pulse lasts only a few hundredths of a second. The period between the individual pulses is in the range of one second or less. Although the pulse frequency varies from pulsar to pulsar, the period of each pulsar is very regular, sometimes even no irregularities are measurable.
The first pulsar was discovered by Antony Hewish and Bell S.J. in 1967. The fastest known pulsar has a period of 0.0016 sec. There are probably about 10,000 pulsars in the Milky Way, but of which less than 400 are known. Pulsars are probably neutron stars and the remains of a supernova. They rotate rapidly and lose their rotational energy by radiation.
