Silence, please!
Our wide, open and very radio-quiet outback is radioastronomy heaven.
TODAY’S ASTRONOMERS make use of every messenger variety bringing information from distant celestial objects. Subatomic particles and gravitational ripples in space-time are recent additions to the list of emissaries. But most of what we know of the Universe arrives via electromagnetic waves – from gamma rays to radio. A wide range of natural processes produces these signals, allowing us to build a truly multifaceted picture of the cosmos.
I’ve spent most of my career in optical astronomy using observations made with visible light. But Australia has a long tradition of excellence in radioastronomy. Our radioastronomers are world leaders in the instrumentation and techniques exploring the Universe at these wavelengths.
They also have something else. Just as optical astronomers need freedom from artificial light to observe faint stars and galaxies, radioastronomers need its equivalent – radio-quietness. If you have a telescope capable of picking up a mobile phone signal at the distance of Pluto, it’s useless putting it near an urban centre where you’re in a cacophony of human-made radio signals.
One of Earth’s most radio-quiet locations is in Western Australia’s interior, some 300km north-east of Geraldton, on Wajarri Yamatji land. This is home to the Murchison Radio-Astronomy Observatory, a vast scrubland hosting several state-of-theart telescope arrays.They include Australia’s precursors to the Square Kilometre Array – the next major international radioastronomy project, which will become the world’s biggest telescope in the 2020s.
Although quite new, the Murchison observatory has already netted amazing discoveries. One has featured here – the radio signature of the Universe’s first stars, born 180 million years after the Big Bang (AG 144).When you realise this incredibly weak signal was found in the middle of the FM radio waveband, you begin to appreciate the true significance of WA’s most unsung natural asset – radio silence.