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Telescope Reveals the Sky in Radio Technicolour

A telescope located deep in the West Australian outback has shown what the universe would look like if human eyes could see radio waves.

Published in the Monthly Notices of the Royal Astronomical Society (, the GaLactic and Extragalactic All-sky MWA (GLEAM) survey has produced a catalogue of 300,000 galaxies observed by the Murchison Widefield Array (MWA) at a remote site north-east of Geraldton.

Lead author Dr Natasha Hurley-Walker of the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) said this was the first radio survey to image the sky in such amazing technicolour. “The human eye sees by comparing brightness in three different primary colours – red, green and blue,” she said. GLEAM does rather better than that, viewing the sky in 20 primary colours. “That’s much better than we humans can manage, and it even beats the very best in the animal kingdom, the mantis shrimp, which can see 12 different primary colours.”

GLEAM is a large-scale high-resolution survey of the radio sky observed at 70–230 MHz, observing radio waves that have been travelling through space for billions of years. “Our team are using this survey to find out what happens when clusters of galaxies collide,” Hurley-Walker said. “We’re also able to see the remnants of explosions from the most ancient stars in our galaxy, and find the first and last gasps of supermassive black holes.”

MWA Director A/Prof Randall Wayth said GLEAM is one of the biggest radio surveys of the sky ever assembled. “Large sky surveys like this are extremely valuable to scientists, and they’re used across many areas of astrophysics, often in ways the original researchers could never have imagined.”

Completing the GLEAM survey with the MWA is a big step on the path to SKA-low, the low frequency part of the international Square Kilometre Array (SKA) radio telescope to be built in Australia in the coming years. “The survey gives us a glimpse of the universe that SKA-low will be probing once it’s built,” Wayth said. “By mapping the sky in this way we can help fine-tune the design for the SKA and prepare for even deeper observations into the distant universe.”