Sept. 10, 2008 -- Last March our planet looked straight down the barrel when one of the universe's most deadly kinds of stellar artillery fired -- and we lived to tell about it.
The March 19 cosmic cannon was a jet of powerful gamma rays which
shot out matter at speeds just a hair shy of the universal speed limit
-- that of light.
The explosion, which occurred not far from the handle of the Big
Dipper, was even more remarkable because it was accompanied by enough
visible light that it could be seen briefly with unaided human eyes.
That's despite the fact the dying mega-star that created the blast was
in another galaxy, a whopping 7.5 billion light-years away.
"At first, I thought something was wrong," said Judith Racusin, a
graduate student at Pennsylvania State University and the lead author
of a paper on the discovery in the Sept. 11 issue of the journal Nature.
"Within minutes, as reports from other observers arrived," she said,
"it was clear this explosion was an especially extraordinary event."
The gamma ray burst, dubbed GRB 080319B, was detected by NASA's Swift satellite,
which is equipped specifically to spot such events quickly. Both
Swift's X-Ray Telescope and its UltraViolet/Optical Telescope were
blinded by the unusually bright blast.
Ensuing observations around the world with other satellites and
ground-based telescopes collected an unprecedented amount of data from
across the electromagnetic spectrum. No fewer than 92 researchers have
combined their work to publish the Nature paper.
"We
really hit the jackpot with this one," said Swift principal
investigator Neil Gehrels at NASA's Goddard Space Flight Center.
"We've been waiting a long time for this one," agreed Grigory Beskin of Russia's Special Astrophysical Observatory.
The plethora of data on GRB 080319B collected around the world has
now been combined to produce the best picture yet of this incredibly
violent stellar event.
It has also revealed that Earth was within range of a very narrow,
ultra-fast central beam of the jet that shot out of the star. Rarely
are these jets so well-aimed at Earth, and it's only the vast distance
of their origins that keeps them from reducing our entire solar system
to cinders.
Gamma ray bursts are the brightest eruptions in the universe,
believed to be caused by very massive stars running out of fuel and
imploding.
Exactly how the jets of nearly light-speed particles are created is
still somewhat of a mystery. But it is clear these jets slam into
material already shed by the star and light it up, creating an
afterglow that can last for months.

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Related Links:
Larry O'Hanlon's blog: Earth Matters
Discovery Space
How Stuff Works: The Electromagnetic Spectrum