In 1933 Karl Jansky announced that the mysterious source of interference in the AT&T transatlantic radio links at 20 MHz was radiation emanating from the center of our galaxy. And thus radio astronomy was born. Until the end of World War II, the subject was developed by a sole individual, Grote Reber, who built a parabolic antenna in his backyard, mapped the distribution of radio radiation along the galactic plane, and identified a number of distinct sources.

The Chris Cross array in New South Wales, Australia, circa 1955.

The Chris Cross array in New South Wales, Australia, circa 1955.

Close modal

Building on the wealth of radar development during World War II, radio astronomy transitioned from small science to big science in the 1950s and is still undergoing enormous growth. The latest big radio telescope array is the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile, which cost about $1.5 billion. A comparable instrument for longer wavelengths is the Square Kilometer Array (SKA), currently under development.

The development of radio astronomy is a fascinating story that contains many lessons about how scientific enterprises grow and flourish. A welcome new book, Four Pillars of Radio Astronomy: Mills, Christiansen, Wild, Bracewell, by R. H. Frater, W. M. Goss, and H. W. Wendt, provides a fascinating window on the remarkable development of Australian radio astronomy in the decade following World War II. As the title suggests, the book focuses on the work of four scientists: Bernie Mills, Chris Christiansen, Paul Wild, and Ron Bracewell. That remarkable group worked at the Radio Physics Laboratory of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO).

Mills invented the eponymous Mills’s Cross, an array that produced a pencil-beam pattern. From the data it provided he derived early source-count distributions, work that had cosmological implications and led him into a bitter rivalry with a competing group in England under Martin Ryle. Mills’s measurement of the position of the radio galaxy Cygnus A led to the first identification of an extragalactic radio source. Christiansen developed a different type of array consisting of two orthogonal interferometric grating arrays that produced fan beams. With it he made the first two-dimensional radio image based on Fourier synthesis of the Sun.

Wild made a clever circular array to image solar emission on short time scales and developed the first classification system for solar radio bursts. Bracewell brought the principles of Fourier transforms to bear on the analysis of data and the problem of restoring and reconstructing images; his work underlies all modern radio interferometry and contributed to the development of medical imaging.

The book is short, concise, entertaining, and very well illustrated. Two of the authors, Frater and Goss, are accomplished radio astronomers who knew and worked with the four subjects of the book. Wendt spent most of his career in banking but earned a PhD in history later in life with a thesis on the history of radio astronomy. Together, they offer many insights based on firsthand interactions with the astronomers and extensive probes into personal letters and other archival material.

The book is not meant to be an encyclopedic tome on early radio astronomy. For that, the reader may wish to consult Cosmic Noise: A History of Early Radio Astronomy by Woodruff T. Sullivan III (2009). Rather, Four Pillars aims to show how innovative scientists can flourish with proper mentoring in a nurturing environment. Hovering in the background on nearly every page of the book is Joe Pawsey, known as the “grand old man” of radio astronomy in Australia; he was a supportive mentor to all four subjects.

The story is focused mainly on Australia in the period 1945–56. I find the depictions to be fair and accurate, and the focus on Australia does not detract from or minimize developments in the rest of the world. The authors carefully explain technical issues in a way that makes the material accessible to a broad audience. Chapters on each of the four subjects start with a description of their early lives, education, and interests, to give an understanding of their character and approach to scientific research. The descriptions are followed by accounts of their achievements and an assessment of their impact.

At the end of the book, the authors attempt to answer the question of how a relatively isolated country like Australia capitalized on the development of radar to become a powerhouse of research in radio astronomy. The authors identify five defining factors that led to success: a clearly identified need, a champion, mentors, a supportive environment, and a sponsor. In the US, the MIT Radiation Laboratory was disbanded and its innovative staff members largely returned to their previous university pursuits. In Australia, government agencies decided to redirect the wartime staff into a few areas for development. One of them was radio astronomy.

However, when resources grew scarce, CSIRO decided to focus on the construction of a 64-meter parabolic dish at the expense of distributed arrays and other new telescopes. That decision split the team. Mills and Christiansen went to the University of Sydney departments of physics and electrical engineering, respectively. Wild stayed at CSIRO, and Bracewell went to Stanford University. Their mentor Pawsey was appointed director of the National Radio Astronomy Observatory in the US in 1961, but died at the age of 54 before he could take the position. His death brought to a close a remarkable period of scientific research. Goss, historian and bioethicist Claire Hooker, and radio astronomer Ron Ekers are working on a biography of Pawsey that will surely further illuminate the golden age of Australian radio astronomy.

James Moran has been at the Harvard–Smithsonian Center for Astrophysics for almost 50 years. He taught radio astronomy to generations of Harvard University students and developed the technique of very-long-baseline interferometry (VLBI) to study cosmic masers.