spacetoday.net: Stellar observations date Milky Way

Posted: Wed, Aug 18, 2004, 9:29 PM ET (0129 GMT)
Observations of two stars in a nearby globular cluster have allowed astronomers to compute the most accurate age of the Milky Way to date. Italian astronomers used the Very Large Telescope (VLT) at the European Southern Observatory to measure the amount of beryllium in two stars in a globular cluster about 7,200 light-years away. Beryllium acts as a "cosmic clock" that allows astronomers to measure the difference between the age of the stars in the cluster — derived from stellar evolution models — and the age of the Milky Way itself. The VLT beryllium data showed that the Milky Way is about 200 million years older than the cluster, Since the cluster is estimated to be about 13.4 billion years old, the Milky Way is therefore about 13.6 billion years old. This is very close to the age of the universe itself, suggesting that the Milky Way started to form within a couple hundred million years after the Big Bang.