Obituary of John Paul Wild

Paul Wild: A Great Pioneer in Solar Radio Astronomy Passes Away

The second winner of the Hale Prize, John Paul Wild, passed away on May 10 in Canberra, Australia. He was born in England in 1923 and was educated at the University of Cambridge, graduating from there in 1943 and later receiving his ScD degree there.

Like many of his contemporary scientists he served as an officer in the Royal Navy during the war, working on radar. At the end of the war in 1947 he joined the CSIRO (Australia’s national research organization) Division of Radiophysics in Sydney, headed by Dr Joseph Pawsey. This Sydney laboratory was one of the two institutions (the other being Cambridge) engaged in pioneering development of radio astronomy techniques using radio receivers adapted from war-time radar sets. By that time, Hey’s discovery of the Sun’s radio emissions made with radar equipment during the war was published and significant work on solar radio bursts had been started by Pawsey, Payne-Scott and others in the Sydney group. Specifically, it was found from single-frequency observations that certain radio bursts showed a delay in onset with decreasing frequency. However, since this was not a universal phenomenon, Wild decided that the next step in this research was to develop a radiospectrograph to record the intensity of solar radio emission as a continuous function of frequency and time. Thus a radiospectrograph was born in 1949, in the frequency range 40–70 MHz, which was later extended up to 220 MHz.

With this radiospectrograph, Wild and his colleagues discovered and distinguished different types of radio bursts to which they gave the labels still in use today: bursts of Type I, II, III and V (Type IV belongs to the French group). They also established the interpretations of Type III bursts as due to beams of accelerated electrons, and Type II bursts as the first evidence for the occurrence of shocks in the solar atmosphere. Because of the radiospectrograph, the Australian group dominated the field of solar radio astronomy at meter wavelengths in the 1950s.

Wild soon realized that in order to understand the origin of solar bursts, besides using plasma physics, one had to build an imaging system. Thus the Culgoora RadioHeliograph was built, initially operating at 80 MHz and later extended to 40, 160 and 327 MHz. This was the first two-dimensional imaging system built for viewing the radio Sun; it was also the first circular array built in radio astronomy. It was operational from 1967 to 1984 and was responsible for the continued prominence of Australian solar radio astronomy.

Paul Wild earned many honors and laurels. These include the Hale Prize in 1980. He was a fellow of the Royal Society, and a fellow of the American Academy of Arts and Sciences. He became the Chief of the Radiophysics Division of CSIRO from 1971–78 and then Chairman of the entire CSIRO from 1978 to 1985. Besides doing solar radio physics, he was involved in doing other innovative projects. In particular, he led the CSIRO team that developed the Interscan Aircraft Landing System that was adopted as the international standard for instrument landing in 1978. As Chairman of CSIRO he was instrumental in establishing the Australia Telescope at Culgoora, which is a VLA-like facility for cosmic observations of the southern skies. After retiring from CSIRO, he led a high-profile consortium trying to bring high-speed trains to Australia.

Finally, a personal note: I had known Paul Wild for more than 40 years. It is hard to find a kinder and gentler person. To me he was always a good and inspiring friend, as he was to all his colleagues and co-workers.

Obituary from Physics Today (December, 2005).