Astronomers record brightest ever supernova

Its life ends in a supernova - an explosion so brilliant that it outshines the combined light from the billions of other stars in its galaxy.

This particular set of celestial fireworks was the brightest of them all, shining five times more brightly than any other supernova seen in the past.

Lead researcher Nathan Smith described the explosion as "truly monstrous".

NASA astronomer Alex Filippenko said: "Of all exploding starts ever observed, this was the king."

Astronomers from the University of California and the University of Texas, who have been observing the phenomenon since September, believe the star that exploded was 150 bigger than our sun.

The researchers said: "Astronomers think many of the first generation of stars were this massive and this new supernova may provide a rare first glimpse of how the first stars died.

"It is unprecedented to find such a massive star and witness its death."

The supernova, named only SN 2006gy, occurred 240 million light years away in a galaxy called NGC 1260, and was studied using NASA's orbiting Chandra X-ray Observatory and Earth-based telescopes.

The explosion, shown here as an artist's impression, occurred long ago but was only detected last year after its light travelled many, many trillions of miles before it could be observed from Earth.

Supernovas, which form when huge stars reach the end of their natural life, usually take a few weeks to reach their brightest point, before dimming into obscurity.

However, this star death took 70 days to reach full brilliance and then stayed brighter than any other known supernova for more than three months.

Now, nearly eight months later, it is still as dazzling as a typical supernova at its peak - and brighter than all the other stars in its galaxy put together.

Scientists believe a star much closer to Earth is capable of ending its life in such a spectacular fashion.

Eta Carinae, a massive star lying in our own Milky Way, 7,500 light years form earth, could follow suit at any time.

Although the explosion would be unlikely to threaten life on Earth, it would be bright enough to turn night into day.

Mario Livio, of the Space Telescope Science Institute in Baltimore, said: "We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case.

"Eta Carinae's explosion could be the best star-show in the history of modern civilisation."