Australia's Astronomer-at-Large

Oct 13, 2024 | australiangeographic.com.au | Fred Watson |Australia's Astronomer-at-Large

Back in September 1969 in a laboratory in north-eastern England, a young, newly minted physics graduate was engaged in a job that no more than a dozen people worldwide would be doing. It was a humble task – fabricating a circular polyethylene air-bag 3.9m in diameter and no more than a couple of centimetres thick. What made the job unique was the purpose of this unwieldy plastic pouch.

Sep 17, 2024 | australiangeographic.com.au | Fred Watson |Australia's Astronomer-at-Large

We know of only one other celestial body where long-lasting reservoirs of liquid pool on the surface, and it’s a very strange world indeed. Saturn’s moon Titan is the second largest in the solar system, eclipsed only by Jupiter’s Ganymede. Its surface is not rock, but ice that’s –180°C. This ice is underlain by a global ocean of liquid water that is, in turn, underlain by a rocky core. Enveloping Titan is an atmosphere that has curious parallels with our own, despite its frigid temperature.

Aug 11, 2024 | australiangeographic.com.au | Fred Watson |Australia's Astronomer-at-Large

To understand why, we have to go back to 1967, when the first of a class of astronomical events known as gamma-ray bursts, or GRBs, was observed. Discovered serendipitously by satellites designed to detect gamma-ray flashes from illegal nuclear tests, the bursts were soon identified as coming from space. Moreover, when new spacecraft were introduced in the 1990s, they were found to originate deep in the universe, well beyond the confines of our Milky Way galaxy.

Jun 24, 2024 | australiangeographic.com.au | Fred Watson |Australia's Astronomer-at-Large |Candice Marshall

So, what is an ocean world? Basically, it’s a ball of rock enveloped in water, which is in the form of ice unless it’s within the “habitable zone” of its parent star – in which case it becomes liquid water. Earth holds that privileged position in our solar system, but further out, ice predominates, with the subtle twist that internal heating from beneath the rocky surface can melt the lower levels of the ice mantle to create a sub-ice ocean.

Jan 8, 2024 | australiangeographic.com.au | Fred Watson |Australia's Astronomer-at-Large |Candice Marshall

Like chocolate bars, however, galaxies come in different shapes and sizes, and not all have a spiral structure. Some are featureless blobs shaped like rugby balls; others are ragtag objects, fittingly known as irregulars. But spirals constitute some 60 per cent of the universe’s estimated 2 trillion galaxies, so what you’ve pictured is fairly accurate. Astronomers think they understand why galaxies have spiral arms.