Detection of the first pulsar

On 28 November 1967, Jocelyn Bell made the first detection of a radio pulsar. Bell (later Bell Burnell), a graduate student at Cambridge University, and Antony Hewish, her adviser, were using a large radio telescope designed by Hewish to observe quasars. Bell had helped build the telescope at the Mullard Radio Astronomy Observatory, near Cambridge. Shortly after Bell began operating the telescope in July 1967, she noticed an odd signal among the reams of data collected each day. Over the next months she observed the signal several more times, and on 28 November she was able to capture a sufficiently detailed recording to show the pulsed nature of the emission. With a period of just 1.3 seconds, the signal was regular but intermittent and appeared to come from the same part of the sky. After ruling out all known natural and humanmade sources, she and Hewish jokingly called the signal LGM-1, for “little green men.” By December, Bell had discovered three more similar signals, coming from different areas of the sky. Confident they had found a new astronomical phenomenon, Bell and Hewish published their findings in the February 1968 issue of Nature. The discovery set off a race to find more such pulsating stars, or pulsars, which turned out to be rapidly rotating neutron stars. In 1974 Hewish—but controversially, not Bell Burnell—was awarded a share of the Nobel Prize in Physics for the discovery.

Date in History: 28 November 1967