Binary 'deathstar' has Earth in its sights

"Viewed from Earth, the rotating tail appears to be laid out on the sky in an almost perfect spiral. It could only appear like that if we are looking nearly exactly down on the axis of the binary system," said Tuthill.

This means we are peering down the barrel of the gun, as when binary supernovae go off, all their energy is focussed into a narrow beam of wildly destructive gamma ray radiation that emanates (both up and down) from the poles of the system.

"If such a gamma-ray burst happens, we really do not want Earth to be in the way," he said. "I used to appreciate this spiral just for its beautiful form, but now I can't help a twinge of feeling that it is uncannily like looking down a rifle barrel."

Sterilising effect

Though the risk may be remote, there is evidence that gamma ray bursts have swept over the planet at various points in Earth's history with a devastating effect on life.

A 2005 study showed that a gamma-ray burst originating within 6,500 light-years of Earth could be enough to strip away the ozone layer and cause a mass extinction. Researchers led by Adrian Melott at the University of Kansas in Lawrence, U.S., suggest that such an event may have been responsible for a mass extinction 443 million years ago, in the late Ordovician period, which wiped out 60 per cent of life and cooled the planet. read more at cosmosmagazine.com