ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Tuesday, February 18, 1997 TAG: 9702180016
SECTION: NATIONAL/INTERNATIONAL PAGE: A-8 EDITION: METRO
DATELINE: LONDON
SOURCE: Associated Press
OBSERVATIONS FROM a European satellite have resolved the paradox that the universe is older than the stars.
Turns out the universe may be bigger than we thought.
A European satellite has measured the position of 120,000 stars, and the results have led scientists to correct one of their basic measuring sticks of the universe.
The results are based on the first analyses of data from the European Space Agency's Hipparcos satellite, launched in 1989. They were presented Friday at a meeting of the Royal Astronomical Society in London.
The Hipparcos measurements of pulsing stars called ``cepheids'' indicated that they are about 10 percent farther away that previously estimated.
That means the universe is bigger and perhaps a billion years older than previously thought. The Hipparcos conclusions may help resolve a paradox that has emerged: that the universe is younger than the oldest stars.
``Until Hipparcos, the cosmic distance scale rested on well-informed guesses,'' said Michael Perryman, project scientist for the European Space Agency. ``The distances we now have, for stars of many kinds, provide for the first time a firm foundation from which to gauge the distances of galaxies.''
Cepheids are an important benchmark for stellar measurements because their brightness is directly related to their pulse - the longer the pulse, the brighter the star.
By comparing the brightness of two cepheids with the same pulse, astronomers can estimate how far apart they are. One of the best-known and closest cepheids is Polaris, the North Star.
Measurements taken by Hipparcos indicated that cepheids were about 10 percent farther away than had been thought. Or, to put it another way, they were a bit brighter than astronomers had guessed.
The Hipparcos measurements indicate the oldest stars are about 11 billion years old, while the universe is somewhere between 10 billion and 13 billion years old.
Other estimates have the stars up to 14 billion years old and the universe as young as 9 billion.
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