A massive star about 150 times the size of the Sun exploded in what could be a long-sought new type of supernova, Nasa scientists have said.
Supernovae occur when huge, mature stars effectively run out of fuel and collapse in on themselves.
But scientists believe this one was obliterated in an explosion which blasted all its material into space.
And astronomers say a star in our own galaxy could soon appear to blow apart with the same celestial fireworks.
The supernova star, called SN 2006gy, was originally discovered in September last year.
The explosion peaked for about 70 days, during which it is thought to have shone about five times more brightly than any supernova seen in the past.
"Of all exploding stars ever observed, this was the king," Alex Filippenko, one of the Nasa-backed astronomers observing the phenomenon, said.
Nathan Smith, who led a joint team from the University of California at Berkeley and the University of Texas in Austin, said it was a "truly monstrous explosion, a hundred times more energetic than a typical supernova".
"That means the star that exploded might have been as massive as a star can get, about 150 times that of our Sun. We've never seen that before."
He said the explosion, which was located some 240 million light-years away, polluted the surrounding environment with metals and elements that are needed for life.
Scientists say that the star which blew apart is similar to Eta Carinae, an enormous star in our own Milky Way, 7,500 light-years from Earth.
They note that before SN 2006gy went supernova, it expelled a large amount of material. Telescopes now see something similar occurring at Eta Carinae, prompting speculation that this star could soon show up as a similar type of supernova.
Dave Pooley, at the University of California at Berkeley, said if Eta Carinae were observed to explode "it would be so bright that you would see it during the day, and you could even read a book by its light at night".
He added there had not been a supernova witnessed in the Earth's Milky Way galaxy for more than 400 years.
Mario Livio, of the Space Telescope Science Institute in Baltimore, said that Eta Carinae could be seen to explode at any time.
"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," he was quoted by AFP as saying.
"Eta Carinae's explosion could be the best star-show in the history of modern civilisation," he said.
The latest SN 2006gy results will appear in the Astrophysical Journal. They incorporate observations from the Lick, Keck and Chandra observatories.