March 21, 2008—Scientists have detected an interstellar explosion so bright that it was briefly visible to the naked eye—from 7.5 billion light-years away.
Viewers looking at the right patch of night sky on Wednesday would have seen several afterglows from the massive gamma-ray burst, slightly brighter than the faintest visible stars.
NASA's Swift satellite captured the unprecedented spectacle using its X-Ray Telescope (left) and Optical/Ultraviolet Telescope (right). The burst was named GRB 080319B, because it was the second of four bursts detected that day—a first for Swift.
GRB 080319B, located more than halfway across the visible universe, crushes the previous record holder for most distant object visible without assistance by three orders of magnitude. That would be the galaxy M33, located just 2.9 million light-years from Earth.
"This burst was a whopper," Swift principal investigator Neil Gehrels, of NASA Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. "It blows away every gamma-ray burst we've seen so far."
Gamma-ray bursts occur when massive stars run out of fuel and collapse, rapidly pouring out enormous amounts of high-energy radiation and particles. Acting like high-power cosmic blowtorches, the particle jets can also heat interstellar clouds to create bright afterglows, according to scientists.
The bursts are the most brilliant occurrences in the universe after the big bang. GRB 080319B's afterglows, for instance, shone 2.5 million times more intensely than the brightest supernova on record.
Researchers are still unsure why GRB 080319B was so bright. Some theories include an originating star with an unusual mass, spin, or magnetic field or an especially concentrated energy jet.
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