1946

Rodney Reserve, on the cliff tops at Dover Heights, just north of Bondi in the eastern suburbs of Sydney, was one of the most remarkable and important astronomical sites in New South Wales. From 1946 to 1954 it was one of the most important radio astronomy sites in the world. In the mid-1940s almost nothing was known about radio waves from space. scientists and engineers from the CSIRO Division of Radiophysics built a range of radio telescopes at Dover Heights and developed new ways of collecting radio data. Many major discoveries were made at Dover Heights.

These established Australia as a world leader in the emerging new science of radio astronomy. Today, CSIRO continues to operate world-class radio telescopes. The Sun was the first object observed with the radio telescopes at Dover Heights. Strong bursts of radio emission were received during times of sunspot activity. When Radio telescopes were pointed towards the sky they revealed areas of concentrated radio emissions. Further investigations shows that the radio waves came from the gas clouds in our Galaxy and from distant galaxies. Scientists in the CSIRO radio astronomy group who worked at Dover Heights included Ruby Payne Scott, John Bolton, Bruce Slee, Gordon Stanley, Kevin Westfold and Dick McGee. In 1951 CSIRO staff dug a 22 metre 'dish-shaped' hole in the sand near the cliff top to make the 'hole-in-the-ground' radio telescope. In 1953 this was enlarged to 25 metres, coated with concrete, and covered with wire mesh to provide a reflecting surface for radio waves. At the time, this was one of the largest radio telescopes in the world. This radio telescope was used with great success to hunt for radio sources in the sky and to study the strong source at the centre of our own Galaxy. This source became the zero-point for the system of celestialco-ordinates that is still used today by astronomers. Near the cliff is a full-size replica of an 8-element Yagi antenna that was built in 1951. The original antenna was used for 'sea interferometry'. In this special technique, the antenna detects radio waves that come directly from a source in the sky, and at the same time other radio waves from the source that are reflected off the sea.

More than 100 sources of radio emission were discovered using the radio telescopes at Dover Heights. A wonderful and unexpected discovery was that many distant galaxies are hugely powerful sources of radio waves. In some galaxies the radio waves are generated by black holes that are hundreds of millions of time more massive than the Sun. The Dover Heights discoveries marked the beginning of the radio study of the Universe and heralded a new era in astronomy. Since then, radio waves have been used to explore the entire cosmos, from the Sun and planets in our solar system, to stars and gas in our Galaxy, and beyond to other galaxies and the most distant reaches of the Universe.

Courtesy the Waverley Library Local Studies Collection.