Bell Burnell , (Susan) Jocelyn

(1943–) British astronomer

Born in Belfast, Northern Ireland, the daughter of the architect who designed the Armagh planetarium, Jocelyn Bell developed an early interest in radioastronomy. She was advised by Bernard Lovell to study physics first and consequently found herself the only woman in a class of 50 physics students at Glasgow University. After graduating from Glasgow she moved to Cambridge, where she completed her PhD in 1969.

As part of her duties she visited the Mullard Radio Astronomy Laboratory each day, filled the inkwells and monitored the 100-foot length of paper chart produced daily by the 4.5-acre telescope. The sky was scanned every four days and, with little computer power available at that time, the data had to be analyzed by hand. One day she identified a strange signal. As it meant nothing to her, Bell simply put a question mark against it. When she noticed it again she drew it to the attention of her supervisor, Antony Hewish. But nothing more was seen for a month. Perhaps, Hewish suggested, it had been a one-off event, a flare which had been and gone.

But after a month it reappeared. On examination Bell found the signals were equally spaced out at intervals of about 1.3 seconds. It was soon established that the signal was genuine and not an instrumental malfunction; nor was it produced by satellites or any terrestrial interference. The source was shown to lie outside the solar system and to have a sidereal motion. A more detailed examination of the signals revealed a regular sequence of pulses at intervals of 1.33730113 seconds with an accuracy better than one part per hundred million. Bell discovered a second signal coming from a different part of the sky in December, and a third and fourth the following month.

Once it had been decided that no LGMs, or ‘Little Green Men’, were involved in the signals, Hewish made the discovery public in 1968. The name ‘pulsar’ was soon coined and soon after Thomas Gold proposed that the signals were emitted by a small, rapidly rotating neutron star. In an earlier age the first pulsar would have been known as Bell's Star; today it carries number CP 1919. Bell's work helped Hewish to gain the 1974 Nobel Prize for physics.

Bell herself married and became Bell Burnell and was appointed in 1968 to a research fellowship at the University of Southampton, where she worked on gamma rays. In 1973 she moved to the Mullard Space Science Laboratory in London to work on x-ray astronomy. Bell moved again in 1982 to head the James Clerk Maxwell Telescope project at the Royal Observatory, Edinburgh. In 1991 she was appointed professor of physics at the Open University, Milton Keynes.