Lighting up the Dark Ages

First there’s this BBC piece, which is basically a summary of a series of papers published over the last few months describing unusual isotopes in tree rings and ice cores from the 8th century, attributable to some kind of external high energy radiation ‘event’. Perhaps a supernova, a solar superflare, or— as per the most recent paper, which is the focus of the BBC piece— a gamma ray burst.

Too intriguing to just leave there. What’s pleasantly surprising is that it’s relatively easy to follow the the back-and-forth in the academic literature— even with the frustrating Nature paywalls, and without understanding much of the detailed science.

Well done BBC/Rebecca Morelle for linking so clearly to your sources.

Here’s the sequence to date:

Japanese researchers describe the mysterious cosmic ray signature. Solar flare (not enough energy to generate the isotopes) or supernova (none noted in the historical record) seem unlikely causes. Nature June 2012 (paywalled)

“A US undergraduate student with a broad interdisciplinary background and a curious mind” uses google to finds references to a ‘red crucifix’ in the sky in 774 AD in the Anglo-Saxon chronicle. So maybe it was a supernova after all. (Nature News June 2012- no paywall)

Then some US researchers say a solar ‘superflare’ could have done it. Nature November 2012 (paywalled). More on Carrington Events here.

And to bring it up to date, German researchers settle on a gamma-ray burst— from colliding black holes or neutron stars— as the most likely culprit. MNRAS January 2013 (open access)

Presumably this will not be the last word on the matter. Wiki has a concise summary here.

Whatever the cause, humans in the 8th century would have been far more resilient to bursts of high energy cosmic or solar radiation compared to our present day technology-dependent societies. But neither they nor us would have been immune to the effects of a close-up gamma ray burst- see my previous piece.

All interesting stuff.

Also interesting, though not particularly relevant to the above: dung beetles navigate using the milky way.

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