By SIMON COLLINS science reporter
Two New Zealand astronomers have found one of the oldest objects seen by human beings - a burst of gamma rays believed to be from a "black hole" 11.5 billion light-years away.
Husband-and-wife team Alan Gilmore and Pam Kilmartin, of Canterbury University's Mt John Observatory near Lake
Tekapo, were the first astronomers to spot the phenomenon after an automatic alert from a US satellite on March 24.
Gamma rays are an energy invisible to the human eye and given off in many chemical reactions.
About 30 years ago, American satellites launched to detect gamma rays from Russian nuclear tests discovered huge natural bursts of gamma rays, occurring every few days somewhere in the universe.
Each burst produced more energy in a few seconds or minutes than the sun will produce in its entire life.
Although many theories have been put forward to explain them, Mr Gilmore said evidence from another gamma ray burst on March 29 showed that at least some were caused by the collapse of once-bright stars into immeasurably dense "black holes".
The latest burst was close enough to Earth for astronomers to observe a "supernova", or collapsing star, occurring the same time.
Don Kniffen, of the US National Aeronautic and Space Administration, said: "We've been searching for a direct link for decades and we finally got it."
Mr Gilmore said the American Association of Variable Star Observers gave cameras to Mt John and to a network of other observatories around the world in late 2001 to track gamma ray bursts.
"This is the first time any of the new equipment was the first to pick up one of these things," he said.
"At 10am on March 24, a satellite picked one up at 23 degrees south in the southern sky. We started looking for it about 10pm that day.
"We compared our pictures with reference pictures taken some years ago, and found this little point of light.
"When we passed it on by email, our American astronomers found it on a picture taken several hours earlier and were able to confirm that it was fading very rapidly.
"Then the European Southern Observatory in Chile pointed its eight-metre telescope at it and found it was 11.5 billion light-years away.
"That was how long light had been travelling to reach us.
"The universe is regarded as being 13.7 billion years old, so it had been travelling for much of the lifetime of the whole universe."
Black holes
* Are the final stage of collapse in large stars.
* Occur because gravity squeezes energy and matter into an infinitely small point.
* Are thought to exist in most galaxies, including the Milky Way.
By SIMON COLLINS science reporter
Two New Zealand astronomers have found one of the oldest objects seen by human beings - a burst of gamma rays believed to be from a "black hole" 11.5 billion light-years away.
Husband-and-wife team Alan Gilmore and Pam Kilmartin, of Canterbury University's Mt John Observatory near Lake
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