What Struck Earth in 775?

ananyo writes "Just over 1,200 years ago, the planet was hit by an extremely intense burst of high-energy radiation of unknown cause, scientists studying tree-ring data have found. The radiation burst, which seems to have hit between 774 and 775, was detected by looking at the amounts of the radioactive isotope carbon-14 in tree rings that formed during the 775 growing season in the Northern Hemisphere. The increase in 14C levels is so clear that the scientists conclude that the atmospheric level of 14C must have jumped by 1.2% over the course of no longer than a year, about 20 times more than the normal rate of variation (abstract). Yet, as the only known events that can produce a 14C spike are supernova explosions or giant solar flares, and neither event was observed at the time, astronomers have a cosmic mystery on their hands."

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[MyLongNickName]

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Effect on Carbon dating?

[Anonymous Coward]

Would this mean carbon dating is inaccurate for items older than 1300 years?

Time to redate the Shroud of Turin?

Southern hemisphere supernova

[vlm]

Yet, as the only known events that can produce a 14C spike are supernova explosions or ... and neither event was observed at the time

... was observed at the time in surviving northern written records.

Are there any detailed written astronomical observations from the southern hemisphere from that long ago?

Also it would be pretty funny if the two guys recording solar observations in 775 both had a rainstorm the day of the largest solar flare.