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People Behind the Science

Jocelyn (Susan) Bell Burnell (1943– )

ocelyn Bell is a British astronomer Milton Keynes, United Kingdom. A winner of the signal showed that it was in fact com-
Jwho discovered pulsating radio stars— of the Royal Astronomical Society's presti- posed of a rapid set of pulses that occurred
pulsars—an important astronomical dis- gious Herschel medal (1989), she has made precisely every 1.337 seconds. The pulsed
covery of the 1960s. significant contributions in the fields of signal was as regular as the most regular
Bell was born in Belfast, Ireland, on X-ray and gamma-ray astronomy. clock on the earth.
July 15, 1943. The Armagh Observatory, She spent her first two years in Cam- One attempted explanation of this cu-
of which her father was architect, was sited bridge building a radio telescope that was rious phenomenon was that it represented
near her home, and the staff there were par- specially designed to track quasars—her an interstellar beacon sent out by extra -
ticularly helpful and offered encouragement Ph.D. research topic. The telescope that she terrestrial life on another star, so initially it
when they learned of her early interest in and her team built had the ability to record was nicknamed LGM, for “little green men.”
astronomy. From 1956 to 1961, she attended rapid variations in signals. It was also nearly Within a few months of noticing this signal,
the Mount School in York, England. She then 2 hectares (about 5 acres) in area, equivalent however, Bell located three other similar
went to the University of Glasgow, receiving to a dish of 150 m (about 500 ft) in diameter, sources. They too pulsed at an extremely
her B.Sc. degree in 1965. In the summer of making it an extremely sensitive instrument. regular rate, but their periods varied over
1965, she began to work for her Ph.D. un- The sky survey began when the telescope a few fractions of a second, and they all
der the supervision of Anthony Hewish at was finally completed in 1967, and Bell was originated from widely spaced locations
the University of Cambridge. It was during given the task of analyzing the signals re- in our galaxy. Thus, it seemed that a more
the course of this work that the discovery ceived. One day, while scanning the charts likely explanation of the signals was that
of pulsars was made. Having completed her of recorded signals, she noticed a rather un- they were being emitted by a special kind of
doctorate at Cambridge, she went on to work usual radio source that had occurred during star—a pulsar.
in gamma-ray astronomy at the University the night and had been picked up in a part of Since the astonishing discovery was an-
of Southampton, and from 1974 to 1982, she the sky that was opposite in direction to the nounced, other observatories have searched
worked at the Mullard Space Science Labora- sun. This was curious because strong varia- the heavens for new pulsars. Some 300 are
tory in X-ray astronomy. In 1982, she was ap- tions in the signals from quasars are caused now known to exist, their periods ranging
pointed a senior research fellow at the Royal by solar wind and are usually weak during from hundredths of a second to 4 seconds. It
Observatory, Edinburgh, where she worked the night. At first, she thought that the signal is thought that neutron stars are responsible
on infrared and optical astronomy. She was might be due to a local interference. After for the signal. These are tiny stars, only
head of the James Clark Maxwell Telescope a month of further observations, it became about 7 km (about 4.3 mi) in diameter, but
section, responsible for the British end of the clear that the position of the peculiar signals they are incredibly massive. The whole star
telescope project based in Hawaii. In 1991, remained fixed with respect to the stars, and its associated magnetic field are spin-
she was appointed professor of physics and indicating that it was neither terrestrial nor ning at a rapid rate, and the rotation pro-
departmental chair at the Open University, solar in origin. A more detailed examination duces the pulsed signal.

Source: From the Hutchinson Dictionary of Scientific Biography. © Research Machines plc 2003. All Rights Reserved. Helicon Publishing is a division of Research Machines.

FIGURE 14.19 The oscillating theory of the universe assumes that the space between the galaxies is expanding, as does the big bang
theory, but in the oscillating theory, the galaxies gradually come back together to begin all over in another big bang.

14-19 CHAPTER 14 The Universe 369