SPACE WIRE
Aussie star counter hits 70 sextillion
SYDNEY (AFP) Jul 22, 2003
An Australian astronomer claimed Tuesday to have completed the most accurate calculation ever of how many stars shine in the visible universe -- some 70 sextillion, or 70 thousand million million million.

Simon Driver of the Australian National University Research School of Astronomy and Astrophysics said the number was more than every grain of sand on all the beaches and deserts on Earth.

Driver's team used some of the world's most powerful telescopes to count the galaxies in one region of the universe close to Earth.

They estimated the number of stars in every grouping by measuring how bright each galaxy was, and then extrapolated this number to cover the visible universe.

The figures were part of the world's largest galaxy survey, the Two Degrees Field Galaxy Redshift Survey, presented Tuesday to the General Assembly of the International Astronomical Union in Sydney.

The Anglo-Australian survey aims to measure the distances to 250,000 nearby galaxies, notably using advanced equipment located at the Siding Springs Observatory in Australia's New South Wales state.

Driver said his team was able to claim the best estimate yet of the number of stars because improved telescopes allowed more accurate counts of galaxies while modern cosmological measurements have given a better picture of the geometry of the universe.

"This is not the total number of stars in the universe, but it's the number within the range of our telescopes," Driver said of his team's figure of 70 sextillion.

"The real number could be much, much larger still -- some people think it is infinite," he said.

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