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.
It flooded NASA instruments with five times the energy of its
nearest competitor, a 1999 blast, said University of Alabama at
Huntsville astrophysicist Rob Preece, author of one of the
studies.
It started with a star that had 20 to 30 times the mass of
our sun but was only a couple of times wider, so it was
incredibly dense. It exploded in a certain violent way.
In general, gamma ray bursts are "the most titanic explosions
in the universe," and this one was so big that some of the
telescope instruments hit their peak, Preece said. It was far
stronger and lasted longer than previous ones.
"I call it the monster," Preece said. In fact, one of the
other studies, not written by Preece, used the word "monster" in
its title, unusual language for a scientific report.
One of the main reasons this was so bright was that relative
to the thousands of other gamma ray bursts astronomers have
seen, the monster was pretty close by cosmic standards. A
light-year is almost 6 trillion miles.
Most of the bursts NASA telescopes have seen have been twice
as distant as this one. Other explosions could be this big, but
they are so much farther away, they don't seem so bright when
they reach Earth, the studies' authors say.
Astronomers say it is incredibly unlikely that a gamma ray
burst — especially a big one like this — could go off in our
galaxy, near us. Harvard's Avi Loeb, who wasn't part of the
studies, put the chances at less than 1 in 10 million.
