Binary Neutron Stars; The Secret Lives of Stars; Special Editions; by Tsvi Piran; 8 Page(s)

In 1967 Jocelyn Bell and Antony Hewish found the first pulsar. Their radio telescope brought in signals from a source that emitted very regular pulses every 1.34 seconds. After eliminating terrestrial sources and provisionally discarding the notion that these signals might come from extraterrestrial intelligent beings, they were baffled. It was Thomas Gold of Cornell University who realized that the pulses originated from a rotating neutron star, beaming radio waves into space like a lighthouse. Researchers soon tuned in other pulsars.

Even as Bell and Hewish were making their discovery, military satellites orbiting Earth were detecting the signature of even more exotic signals: powerful gamma-ray bursts from outer space. The gamma rays triggered detectors intended to monitor illicit nuclear tests, but it was not until six years later that the observations were made public; even then, another 20 years passed before the bursts' origin was understood. Many people now think gamma-ray bursts are emitted by twin neutron stars in the throes of coalescence.