GALAXY HISTORY WRITTEN IN DUST

Australian dust grain travelled for 7 billion years

Astronomers have reconstructed the journey of a single grain of dust, from its formation in a dying star more than 7 billion years ago to its arrival in Murchison, Victoria, aboard a meteorite.

Seven billion years ago, a tiny dust grain formed in the outermost layers of a ’red giant’ star. The old star was using up its final fuel before burning out for good, spreading dust and gas out into space. For a long time, that small dust grain drifted in the Milky Way until it became part of a huge cloud of gas and dust, which collapsed and came together to form our Solar System. Our dust grain ended up as part of a meteor which fell to Earth in 1969 near the village of Murchison, off the Goulburn Valley Highway in Victoria, north of Melbourne. More recently it has become the focus of a lab in Chicago.

The Solar System must be teeming with the remains of stars that burned out billions of years ago, spreading dust and gas in just this way. But until now astronomers have had no real proof of this process. Then in January 2020, after scientists from the Field Museum of Natural History and the University of Chicago extracted our tiny dust grain from the Murchison meteorite, they were able to publish their