From: Victoria University of Wellington
Posted: Friday, August 26, 2005
A Victoria University scientist who has found the key to dating the very beginnings of our Solar System will have his work published in the prestigious scientific journal Nature today.
Dr Joel Baker, Senior Lecturer in the School of Earth Sciences, is the lead author of a report that shows it is possible to date the formation of our Solar System's oldest rocks with unprecedented resolution, using cutting-edge geochemical analytical techniques. The results indicate the Solar System is at least three million years older than previously thought.
Dr Baker, who completed a Master of Science at Victoria before undertaking a PhD and ten years of research in Europe, says compressing his results onto a more meaningful timeframe can make the significance of his work clearer.
"If the 4.56 billion year history of the Earth is compressed into one day, then Homo Sapiens appeared just a few seconds before the end of the day. In contrast, my colleagues and I are building a picture of the very first seconds of the Solar System to see why and how it formed."
Dr Baker's analysis of isotopes in an extremely small quantity of lead (one billionth of a gram) from a meteorite found in the Sahara Desert has shown this meteorite is 4.5662 billion years old - just one million years younger than the conventionally accepted age of the Solar System and at least 500 million years older than Earth's oldest rocks.
This meteorite is an igneous rock, like those erupted from volcanoes on Earth, and is now, thanks to Dr Baker's research, confirmed as the oldest and most precisely-dated igneous rock in our Solar System.
"Meteorites from space that arrive on Earth mainly come from asteroids that orbit between Mars and Jupiter," Dr Baker explains.
"These asteroids formed around the young Sun at the very beginning of our Solar System some 4.56 billion years ago. These meteorites are our only direct record of the birth of our Sun and formation of planets around it and, ultimately, why we are here on Earth."
The research shows that asteroids hundreds of kilometres across grew in a few hundred thousand years and then melted incredibly quickly.
"However, melting of these asteroids was not caused by the same processes which produce volcanism on Earth. The melting was driven by heating from the decay of short-lived radioactive isotopes that were injected into the young Solar System from the supernova, or explosion, of a nearby dying star. This process may have ultimately triggered Solar System formation, which our results now indicate is at least three million years older than previously thought.'
Victoria's Dean of Science, Professor David Bibby, says Dr Baker has made a remarkable discovery and demonstrated that he is a world leader in his research area.
"Dr Baker is pushing the boundaries in isotopic geochemistry - a field that has exciting applications in fields as diverse as geology, environmental chemistry, archaeology, palaeontology, mining, medicine and, of course, astronomy. The article in Nature recognises the importance of Dr Baker's research and once again confirms Victoria's reputation for having leading researchers teaching our students."
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