Brief recap: Upon studying the tree rings in Japanese cedar trees, researchers found evidence for a sudden increase in 14C in the atmosphere. What, oh what, could have caused this? Supernova? Solar flare? Nope, said the authors. There’s no evidence for either.
However, a new piece of historical evidence has been unearthed. Upon browsing through the Anglo-Saxon Chronicle’s 8th century entries, Jonathon Allen, biochemistry major at the University of California, found mention of something interesting in the year 774 AD, which is exactly the right period. Apparently, it is noted that:
This year also appeared in the heavens a red crucifix,…
Aha, a clue.
A supernova after all? Perhaps. A dust cloud might explain why it wasn’t seen by a wider audience and mentioned profusely elsewhere.
There are other options, though, says physicist David Olson in the Nature News Feature. Perhaps the Northern Lights? Or an ice-crystal display, where sunset light hits high-altitude ice particles?
So, does the ‘red crucifix in the heavens’ explain the atmospheric anomaly the tree rings have shown us?
Allen, J. (2012). Astronomy: Clue to an ancient cosmic-ray event? Nature DOI: 10.1038/486473e
Lovett, R.A. (2012). Ancient text gives clue to mysterious radiation spike. Nature DOI: 10.1038/nature.2012.10898