'Giant' hole found in universe
2007-08-25 13:33
Paris - US scientists have found a giant hole in the universe, measuring almost a billion light-years across and completely empty of any matter, dark or otherwise, a study said on Friday.
"Not only has no one ever found a void this big, but we've never even expected to find one this size," said Lawrence Rudnick, astronomy professor at the University of Minnesota.
Astronomers have known for years that the universe has some voids which are largely empty of matter, said the study published in the Astrophysical Journal. But most were much smaller than the void found by Rudnick and his team.
The team reached its findings after studying data from the NRAO VLA Sky Survey, and concluding that there was a fall in the number of galaxies in the region of the constellation, Eridanus, southwest of Orion.
The survey had allowed the observation of about 82% of the sky thanks to the Very Large Array (VLA) telescope based at the National Radio Astronomy Observatory (NRAO) in New Mexico.
'Cold spot'
"We already knew there was something different about this spot in the sky," said Rudnick, in a joint statement with the NRAO.
It had been dubbed a "cold spot" when astronomers began analysing the faint radio waves, known as the Cosmic Microwave Background (CMB), which are the remaining radiation left from the "Big Bang."
That data had been gathered in 2004 by the Wilkinsons Microwave Anisotopy Probe statellite, launched by the US space agency Nasa in 2001.
"Although our surprising results need independent confirmation, the slightly lower temperature of the CMB in this region appears to be caused by a huge hole devoid of all matter roughly 6-10 billion light-years from Earth," said Rudnick.
French astrophysicist Jacques Delabrouille told AFP it was "extraordinary how the two observations showed the same point" - the cold spot found in the cosmic microwave background and drop in galaxies in the sky survey.