Jack Hobart Piddington (1910?1997), radar scientist and radio astronomer, was born on 6 November 1910 at Wagga Wagga, New South Wales, elder child of Frederic Clarence Piddington, wool classer, and his wife Leonie Mabel, nee Millenet, both New South Wales-born. Jack’s middle name recognised the place his paternal great-grandfather had settled in the 1830s. His parents divorced when he was six, leaving his mother facing financial hardship. He attended the Wagga Rural and High schools until his family moved to Bondi, Sydney. In 1926 he enrolled at Sydney Boys’ High School where he showed exceptional talent for mathematics and physics. He was dux in 1928, one of many awards and honours he was to receive over his career.

With support from a State bursary, the Barker scholarship and the Horner exhibition for mathematics, Piddington enrolled at the University of Sydney (BSc Hons, 1932; BE Hons, 1934; MSc, 1936). He was awarded the university medal in 1934, and for the next two years worked on radio and electronic research in the university’s department of electrical engineering. This led to an appointment to the Radio Research Board of the Council for Scientific and Industrial Research (CSIR), followed by a Walter and Eliza Hall fellowship for postgraduate study at the University of Cambridge (PhD, 1938) where he was introduced to radar science. His thesis on the scattering of radio waves was supervised by (Sir) Edward Appleton, later a Nobel prize laureate. On 19 September 1936 Piddington married Catherine Broughton Wynne-Dyke at the Parish Church, Woburn Square, London.

Piddington returned to Sydney in 1938, and the following year joined CSIR’s radiophysics division, with his close friend David Martyn as its inaugural chief. He initially worked on the radar detection of ships, but following Japan’s attack on the United States of America in December 1941 and subsequent advance through South-East?Asia he designed an air raid warning radar which was rushed into production. One unit was sent to Darwin but, as he was furious to learn, delays in installation led to no warning of the devastating air raid of 19 February 1942. He travelled widely advising on radar, including to Britain in early 1944.

After the war the radiophysics division turned to the peacetime applications of radar and radio, and in 1949 became part of the Commonwealth Scientific and Industrial Research Organization (CSIRO). Piddington joined a research group led by Joseph Pawsey that was pioneering the new science of radio astronomy. With Harry Minnett, Piddington carried out observations in 1948 of the thermal radiation emitted by the Moon. They concluded that a thin layer of fine powder covered the solid lunar surface, a bold prediction verified by the Apollo 11 astronauts in 1969. On 18 June that year Piddington, having been divorced by Catherine in 1940, married Nancy Gould MacDougall at St Mark’s Church, Darling Point. In 1950 he and Minnett used a wartime radar antenna to carry out the first sky survey of high-frequency (microwave) radio emissions. They named an intense source of radiation Sagittarius A, now known to be a supermassive black hole at the centre of the Milky Way galaxy. Piddington then proposed building a large radio dish, but the radio astronomy group failed to support the idea, ending his time as an observational radio astronomer. The rest of his career was devoted to theoretical astrophysics, covering such fields as radio emissions from the Sun, partially ionised gases, and the Earth’s magnetosphere. His book for non-specialists, Radio Astronomy , appeared in 1961.

Piddington was a scientific recluse who was the sole author on all but a handful of his publications. Minnett recalled him as ‘mild mannered and reserved … essentially a kindly, somewhat shy man’ (Melrose and Minnett 1998, 240). A journalist thought his unassuming physical presence reminiscent of ‘a good-looking teacher or public servant whose speciality is water and sewage’ (Lindsay 1952, 11). Although Piddington helped make Australia an early world leader in radio astronomy, it took another generation before a vibrant theoretical community emerged to complement his observational colleagues. He was elected a fellow of the Royal Astronomical Society (1952), and of the Australian Academy of Science (1963). His second marriage ended in divorce in 1962, and on 30 September 1965 he married Patricia Olive Devereaux, a sales assistant, at the District Registrar’s Office, St Leonards.

In 1966 Piddington transferred to CSIRO’s National Measurement Laboratory as chief research scientist, and worked on the role of magnetic fields in astrophysics before retiring in November 1975. He maintained an association with CSIRO as a senior research fellow until 1984, and continued his lifelong enthusiasm for competitive tennis. In all, he published over 130 research papers. On 16 July 1997 he died at Mosman and was cremated, survived by his wife, the son from his first marriage, and the two daughters from his second.