Gamma ray riddle solved

Astronomers reckon they have solved the mystery of "gamma ray bursters" - points in the sky which emit brief but incredibly powerful bursts of very short-wave radiation. Since the phenomenon was first observed, in 1973, theories about their origin have abounded - from neutron stars to the warp drives of alien space craft.

Writing in the science journal Nature today, a team at the University of Alabama, coordinating an international effort, said they had seen a point of light to match the source of gamma rays. Usually such bursts are so brief that by the time a telescope can be trained on them, they have died away.

The team said the intense light, discovered 20 minutes after the initial gamma rays, could have come from an explosive collision between two neutron stars - the incredibly dense remnants of burnt-out stars - at the far end of the universe. If this is so, the explosion would be the brightest in the universe, perhaps releasing as much energy in a few seconds as the sun does in a billion years.

The telescopes showed a blur in the sky which lasted for a month before it faded out.