Satellite data proves stars are younger than Universe

Astronomers can breathe easy: the stars really are younger than the universe. It turns out that a key "ruler" used to measure interstellar distances - and hence, by inference, the age of stars and galaxies - has been wrong by between 10 and 15 per cent. According to Neill Reid at the California Institute of Technology, data from the European Space Agency's Hipparcos satellite leads to the conclusion that the oldest stars in the universe are actually 11 to 13 billion years old, rather than 16 to 18 billion years old, as had been thought.

The new results, to appear in July's Astrophysical Journal, will be of great interest to cosmologists, Dr Reid says, because estimates of the age of the universe, based on tracking back the current rate of expansion, suggest that the Big Bang occurred no more than about 13 to 15 billion years ago. "The ideal sitution would be to have the same answer independently given by stellar modeling and cosmology," he said.

Dr Reid's method focuses on the types of stars found in globular clusters - spherical accumulations of hundreds of thousands of individual stars. These have long been known to be the among the earliest objects to form in the universe, since the stars are composed mainly of hydrogen and helium, and because the clusters themselves are distributed throughout a sphere 100,000 light years in diameter, rather than confined, like the sun, within the flattened pancake of the galactic disk.