pulsar

Celestial source that appears to flash at radio and other wavelengths at regular intervals, ranging from a few seconds to a few thousandths of a second. Pulsars are rapidly rotating neutron stars. They were discovered in 1967 by Jocelyn Bell Burnell and Antony Hewish at the Mullard Radio Astronomy Observatory, Cambridge, England.

Pulsars slow down as they get older, and eventually the flashes fade. Millisecond pulsars (flashing about 1,000 times a second) are thought to be more than a billion years old. A few pulsars, one (estimated to be 1,000 years old) in the Crab nebula and one (estimated to be 11,000 years old) in the constellation Vela, give out flashes of visible light.