WASHINGTON The biggest intergalactic explosion ever seen by man was detected in the Constellation Ursa Major by an Italian/Dutch satellite and a NASA gamma ray satellite, scientists said Wednesday. The gamma ray burst, which lasted about one second, occurred 12 billion light years from Earth and was as luminous as all the rest of the entire universe, releasing energy as much as the 10 billion trillion stars in the universe combined, scientists said.

The findings were published in the journal Nature. The National Aeronautics and Space Administration (NASA) and Columbia University said the explosion was detected last December 14, and designated GBR971214. NASA's Hubble space telescope conducted follow up observations on the afterglow. Researchers detected that a shift in the red light of the explosion was 3.42, an extraordinarily large number that indicated the light emitted by GBR971214 took 12 billion years to travel to Earth, 80 percent of the most widely accepted age of the universe, 15 billion years.

The event thus took place some 8 billion years before the Earth's formation, Columbia University summed up. The expanding universe shifts light from distant stars toward the red end of the visible spectrum, so the larger the shift the more distant the star. In a region about a hundred miles across, the burst created conditions like those in the early universe, about one millisecond after the Big Bang which scientists believe caused formation of the universe, one investigator said.

The cause of the explosion is not precisely known. A leading theory is that it was caused by the collision of two neutron (very old) stars. The explosion, however, took place in a region of stellar birth, not old age, and no exploding star (supernova) approaches the power of GBR971214. The observation could be consistent with a hypernova, which in theory involves the collapse of an extraordinarily large star 80 to 100 times larger than the sun and formation of a black hole.

(DPA)