Wilbur Norman (Chris) Christiansen
- Melbourne, Australia
- Death date
- Associated organizations
- Fields of study
- Radio astronomy
A pioneer radio-astronomer, Wilbur Norman Christiansen helped prove that we live in a spiral galaxy. When radio telescopes were revolutionary technology, he not only designed and operated them, he even started building them with his bare hands.
Christiansen received a BSc from the University of Melbourne in 1934, an MSc in 1935 and a DSc in 1953. In 1980 he was awarded a DScEng from The University of Sydney.
Chris Christiansen, as he was known, joined the CSIRO in 1948 and was a senior principal research officer at the CSIRO's Division of Radiophysics in the 1950s when he came up with an idea for a telescope to study a new science, mapping the sun.
Instead of constructing one large antenna to snare radio noise pouring out of our nearest star, he proposed 32 dish-shaped antennas, running east-west across the old World War II airfield known as Fleurs Field, near Badgerys Creek, in Sydney's south-west.
Running north-south would be a second line of antennas. Together the 64 dishes, dubbed the Chris Cross, gave scientists a powerful tool to explore the sun. One morning, irritated by bureaucratic construction delays, Christiansen grabbed his secretary and a colleague, drove a truckload of star posts and wire to the site, and began work.
“All day we belted in the star posts," his colleague, the future astronomy professor Don Mathewson, recalled. They laboured "the next day, and the next until the cross-shaped fence was completed". Christiansen fired off an invoice to his boss, followed by news that, with the fence done, they would begin pouring concrete for the foundations. Within a week the CSIRO dispatched workers to tackle the task.
Christiansen, who has died at 93, was born in Melbourne, the son of a clergyman. After his father died, his mother supported the family by teaching music.
“I always went to sleep listening to Beethoven, Brahms and so on," he told Emeritus Professor Bob Crompton in a 1997 interview for the Australian Academy of Science. Christiansen's inventiveness was apparent at school. When teachers punished him with 100 lines, he developed a technique to do five lines at a time, which proved "very popular with my cobbers".
After obtaining a masters degree and a doctorate at Melbourne University he went to work in 1930 as a physicist at the Commonwealth X-ray and Radium Laboratory. During World War II. Joining Amalgamated Wireless Australasia (AWA) in 1937, he developed ways to make it harder for the enemy to eavesdrop on Australia's radio links with its far-flung allies.
With the discovery that the sky was awash with mysterious radio signals, radio-astronomy was born. Christiansen wrote to the CSIRO and landed a job in 1948.
Using antennas in Sydney and Tasmania, he watched solar eclipses, seeking the source of some of the puzzling noise. As each site saw the eclipse at different times he was able to narrow the origin of the signals to particular areas on the sun's surface. "Then I thought, ‘we can't wait for these damned eclipses’,” he told Crompton. The solution was a string of dish-shaped antennas alongside Sydney's Potts Hill reservoir. Only one of the team ever fell in.
He and colleagues would dash out to push the dishes into place by hand, keeping them facing the sun as it crossed the sky. "The running kept us thin and healthy," he said.
They later confirmed that the entire galaxy was emitting radiation. "We ... mapped it all over the Milky Way", producing the first radio evidence "that we were living in a spiral galaxy".
Christiansen became Professor and Head of the Department of Electrical Engineering at The University of Sydney in 1960, holding it until 1978. In 1963, the CSIRO handed the Fleurs field observatory site to The University of Sydney Electrical Engineering Department.
On leave in 1966 from his post as Professor and Head of electrical engineering at The University of Sydney, Christiansen visited Beijing to help China's planning for a radio telescope. Arriving on the eve of the Cultural Revolution, he saw work on the telescope grind to a halt as young workers spent all their time at meetings. "I got fed up one day," the scientist recalled, confessing he cried: "For God's sake get me a pick and shovel and a crowbar."
The ground was frozen stiff but he started digging post holes. He soon abandoned the work, but the next day the whole job was done. The boys had worked all night, at minus-30 degrees.
Christiansen's interests extended beyond astronomy. He was outspoken in his criticism of the Vietnam War and protested against US plans to detonate a hydrogen bomb in space, in the Van Allen radiation belts that girdle the globe. He thought it a crazy experiment that could have catastrophic effects.
A former vice-president of the International Astronomical Union and president of the International Union of Radio Astronomy, in 1969 he co-authored Radio Telescopes, regarded by radio-astronomers as a standard text. In 1985 it was published in Russian and Chinese. He was a member of the Australia-China Council of the Department of Foreign Affairs from 1979 to 1982.
He retired in 1979 moving to Canberra where he became a Visiting Fellow at the Mt Stromlo Observatory of the Australian National University until 1983. Christiansen is survived by his sons, Steve and Tim. His wife, Elspeth, died in 2001. Their son Peter died in the 1990s.
"Radio Telescopes", 2nd edition, by W.N. Christiansen and J.A. Hogbom, Cambridge University Press (1969)