The extreme stargazer's guide to the cosmos

The extreme stargazer's guide to the cosmos

AS A teenager, Bryan Gaensler gazed at the heavens from the backyard of his Sydney home, fascinated by a light that had suddenly appeared in the night sky.

It was February 1987, and a distant star in the constellation of Dorado had ended its life suddenly in a massive explosion, so bright that it was visible to the human eye.

Web of intrigue ... the Red Spider Nebula has one of the hottest stars.


Photo: ESA & Garrelt Mellema

Gaensler had been a fan of astronomy since he was a child, and seeing this supernova strengthened his resolve to pursue a career studying the universe, he says.

''I was able to spot it [the supernova] every night until it gradually faded away over the next few weeks. It was a huge thrill to know that the light that was entering my eyes had begun its journey in an unimaginably violent detonation 170,000 years earlier,'' Gaensler recalls.

Gaensler, an Australian Laureate Fellow at the University of Sydney and director of the Centre of Excellence for All-sky Astrophysics, recounts this teenage experience in his new book, Extreme Cosmos, which takes the reader on a tour of the most extraordinary features of our universe.


Among his insights into the brightest, heaviest, fastest and hottest celestial bodies are descriptions of a neutron star so magnetic it would wipe data from a credit card 100,000 kilometres away, a star that is 1500 times the size of our sun and another star moving at about 2.5 million kilometres an hour.

When he was very young, Gaensler imagined his main preoccupation as an astronomer would be to discover new stars. And his first stellar find - in 1994 - was a big thrill, he writes.

''I sat quietly for a few minutes, alone with my discovery, cherishing the fact that there was something out there that only I knew about.'' But he later realised the main aim of those who study the universe is to try to understand how it works.

We live in a rather insalubrious spot in the cosmos to do this, on a small planet orbiting an ordinary star in a quiet suburb of the Milky Way, he says. And, clever though humans are, our brains evolved to help us survive as hunter-gatherers rather than comprehend the unimaginably large numbers that are needed to describe the complexity of the cosmos.

This makes it all the more remarkable that, in a little more than 100 years, people have learnt so much about the 13.7 billion-year history of the universe since the Big Bang.

The largest structure found so far is the Sloan Great Wall a ''colossal filament of thousands of galaxies'' that stretches for 1.4 billion light years.

And the fastest object measured - the Oh My God particle - was detected in the United States 20 years ago. It is thought to have been a proton, travelling at almost the speed of light, which is just over a billion kilometres an hour.

Supernovae, such as the one Gaensler saw as a teenager, are bright. But gamma ray bursts are 100 to 1000 times more luminous, and the record setter occurred in 2008. It was easily visible to the eye for about 30 seconds, even though it came from 7.5 billion light years away - meaning it occurred even before our sun and earth were born.

Even though much has been learnt, each new find raises more questions, says Gaensler, a former Young Australian of the Year. ''There is an endless road of discovery and delight ahead. The golden age of astronomy is only now just beginning.''