WASHINGTON (AP) — Astronomers call it the monster. It was the biggest and brightest cosmic explosion ever witnessed. Had it been closer, Earth would have been toast.
Orbiting telescopes got the fireworks show of a lifetime last spring when they spotted what is known as a gamma ray burst in a far-off galaxy.
The only bigger display astronomers know of was the Big Bang — and no one, of course, was around to witness that.
"This burst was a once-in-a-century cosmic event," NASA astrophysics chief Paul Hertz said at a news conference Thursday.
But because this blast was 3.7 billion light-years away, mankind was spared. In fact, no one on Earth could even see it with the naked eye.
A gamma ray burst happens when a massive star dies, collapses into a brand-new black hole, explodes in what's called a supernova and ejects energetic radiation. The radiation is as bright as can be as it travels across the universe at the speed of light.
A planet caught in one of these bursts would lose its atmosphere instantly and would be left a burnt cinder, astronomers say.
Scientists might be able to detect warning signs of an impending gamma ray burst. But if a burst were headed for Earth — and the chances of that happening are close to zero, astronomers say — there wouldn't be anything anybody could do about it.
NASA telescopes in orbit have been seeing bursts for more than two decades, spotting one every couple of days. But this one, witnessed on April 27, set records, according to four studies published Thursday in the journal Science.