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The Australian National University

Eyes on the Skies

Clabon Allen using the Heliostat, 1942 (Mt Stromlo Archives)
Nebula (Mt Stromlo Archives)
Mike Bessell (Mt Stromlo Archives)

Stromlo has always attracted the world's best scientists and continues to be part of many of the world's most significant astronomical projects.

In its original incarnation as a solar observatory, Mt Stromlo played host to renowned astronomer Clabon (Cla) Allen, who used the Heliostat (sun telescope) to measure and photograph the spectrum of the Sun. By analysing the intensity of the dark lines that cross the Sun's spectrum, Allen made a significant contribution to the understanding of the elements that make up the Sun' atmosphere and developed a Solar Atlas which gained the Observatory international recognition.

Acclaimed instrumentalist and astronomer Ben Gascoigne's research into the Magellanic Clouds - two small galaxies that orbit the Milky Way - radically altered our perception of the universe. By observing the colours of stars, Gascoigne found that the distances between the two Clouds had been considerably underestimated. As this distance had been previously used as a measuring standard, this important discovery effectively doubled the estimated size of the universe.

During the 1990s, Director Jeremy Mould and his colleagues accurately measured the age of the Universe. Using the Hubble Space Telescope, Mould and his team undertook measurements of pulsating variable stars called Cepheids, and were able to measure the 'Hubble Constant'. This measurement showed how fast the Universe is expanding, which could then be used to define the age of the Universe to 13.7 billion years. The findings of this project are recognised as one of the most significant measurements in astronomy.

Perhaps Stromlo's greatest astronomical contribution was the discovery that the universe is expanding at an accelerating rate. Professor Brian Schmidt formed the High-Z Supernova Search Team in 1994 to observe the characteristics of stellar explosions - or supernovae. This international partnership analysed the characteristics of bright, distant supernovae and found that they were much fainter than expected. The team's surprising discovery meant that the expansion of the Universe was not slowing down as expected, but was in fact speeding up. This breakthrough changed the understanding of the nature of the Universe, and as a result Schmidt and two other researchers were awarded the 2011 Noble Prize in Physics.

My own reaction is somewhere between amazement and horror. Amazement because I just did not expect this result and horror in knowing that it will likely be disbelieved by a majority of astronomers - who like myself are extremely sceptical of the unexpected.

- Prof Brian Schmidt reacts to his discovery of an accelerating universe

Eagle Nebula (Mt Stromlo Archives)
Professor Brian Schmidt, 2011 (RSAA)
Orion Nebula (Mt Stromlo Archives)

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