From Nature magazine

An eerie "red crucifix" seen in Britain's evening sky in ad 774 may be a previously unrecognized supernova explosion — and could explain a mysterious spike in carbon-14 levels in that year's growth rings in Japanese cedar trees. The link is suggested today in a Nature Correspondence by a US undergraduate student with a broad interdisciplinary background and a curious mind.

A few weeks ago, Jonathon Allen, a biochemistry major at the University of California, Santa Cruz, was listening to the Nature podcast when he heard about a team of researchers in Japan who had found an odd spike in carbon-14 levels in tree rings. The spike probably came from a burst of high-energy radiation striking the upper atmosphere, increasing the rate at which carbon-14 is formed (see 'Mysterious radiation burst recorded in tree rings').

But there was a problem: the only known causes of such radiation are supernova explosions or gigantic solar flares, and the researchers knew of no such events in ad 774 or 775, the dates indicated by the tree rings.

Intrigued, Allen hit the Internet. "I just did a quick Google search," he says.

His long-standing interest in history was helpful, he notes. "I knew that going that far back, there's very limited written history," he says. "The only things I'd ever seen or heard of were religious texts and 'chronicles' that listed kings and queens, wars and things of that nature."

His search found the eighth-century entries in the Anglo-Saxon Chronicle at the Avalon Project, an online library of historical and legal documents hosted by Yale University in New Haven, Connecticut. Scrolling down to the year ad 774, Allen found a reference to a "red crucifix" that appeared in the heavens "after sunset".

Hidden in the heavens
"It made me think it's some sort of stellar event," Allen says. Furthermore, he notes, the redness might indicate that the source was hidden behind a dust cloud dense enough to scatter all but a small amount of red light. Such a cloud might also prevent any remnants of the proposed supernova being seen by modern astronomers.

Scientists in the field are impressed. Geza Gyuk, an astronomer at Chicago's Adler Planetarium in Illinois, who has used the Anglo-Saxon Chronicle to investigate past astronomical events, says that Allen might be on to something. "The wording suggests that the object was seen in the western skies shortly after sunset," he says. "That would mean that it would have moved behind the Sun [where it could not be seen] as Earth orbited the Sun. That, along with the dimness of the 'new star' due to dust would go a long way to explaining why no one else would have seen or recorded the event."

Nevertheless, says Donald Olson, a physicist with an interest in historical astronomy at Texas State University in San Marcos, "Early chronicles can be difficult to interpret in an unambiguous way."

As far back as 1870, he says, John Jeremiah published an article in Nature that referred to the same wording from the Anglo-Saxon Chronicle. Jeremiah proposed then that it might have been an early description of the Northern Lights.

"Another possible explanation could be an ice-crystal display," adds Olson, noting that the red "crucifix" could have been formed by sunset light illuminating high-altitude ice particles in both vertical and horizontal bands of light.

But, it could also have been a previously unrecognized supernova. Plenty of supernovae now known to astronomers "are simply missing" in the historical record, says Gyuk. "The sky is a large place and the historical record is not very good."

This article is reproduced with permission from the magazine Nature. The article was first published on June 27, 2012.

NATURE PODCAST: Cosmic Crucifix
Jonathon Allen discusses his discovery with the Nature podcast team.

6 Comments

1. 1. Laroquod 08:46 AM 6/28/12

   A commenter named 'Mattuk' made this exact discovery in the Anglo-Saxon Chronicle in response to Richard Lovett's *previous* article about this supernova in Scientific American? Why no acknowledgement? Doesn't anybody at sciam read their own comments sections?
   
   Here's the source...
   
   http://www.scientificamerican.com/article.cfm?id=mysterious-radiation-burst-rec
   
   Unless Jonathon Allen and 'Mattuk' are one and the same person, seems like the internet beat science to the punch and nobody in the establishment noticed, which is a rather telling turn of events.

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2. 2. jtdwyer 08:38 PM 6/28/12

   Laroquod - Excellent comment!
   
   Unless Jonathon Allen is 'Mattuk', in all fairness I strongly suggest that Scientific American should support its readership by contacting the owner of the 'Mattuk' id to properly attribute his first mentioning the Anglo Saxon Chronicles entry for 774 AD, noting the occurrence of a 'red crucifix' in the sky, as a possible supernova accounting for the Japanese tree ring evidence.
   
   While, as reported here, Jonathon Allen published a June 27 a Nature Correspondence suggesting the same cause for the Japanese tree ring evidence, his suggestion was preceded by more than 3 weeks by the 'Mattuk' comment. Again, assuming that 'Mattuk' is not Jonathon Allen, he should be accredited with the initial discovery.
   
   The original research report was only published online in Nature on June 3 - the news report was published online at http://www.nature.com/news/ancient-text-gives-clue-to-mysterious-radiation-spike-1.10898 as well as sciam.com on the same day. The 'Mattuk' comment you identified was posted on June 5 at 4:12 AM EDT to the sciam.com article and specifically quotes the Anglo Saxon Chronicle for 774 AD and asks, "Could the celestial crucifix be a supernova?"
   
   Interestingly, it's stated in a posting on June 5 at 00:14 GMT in http://www.theregister.co.uk/2012/06/05/mysterious_energy_blast/
   "Speaking of comments, one reader of the Nature.com announcement of the researchers' paper noted that there was, indeed, a contemporary mention of a celestial display during the time in question. The Anglo-Saxon Chronicles note that in 774 A.D., "This year also appeared in the heavens a red crucifix, after sunset.""
   
   However, I can find no such comment posted to the referenced nature.com (Nature News) article.
   
   Strangely, a Kit Newton posted a comment to the Nature News article also on June 5 asking, "What about an event on Earth rather than in space? ...a mushroom cloud might well have been interpreted as a "red crucifix" at that time:) - but a terrestrial event would not need to be of cosmic scale energy to affect our atmosphere." Curiously, I find no previous mention of a 'red crucifix' except in any but the 'Mattuk' comment.
   
   Also strange, a Mark Webster posted a comment to the Nature News article on June 10 asking "What about historical records? The Anglo-Saxon Chronicle:" then quotes from the entry but does not mention the "red crucifix" statement.
   
   SA editors - please follow up to ensure the correct discoverer of the Anglo Saxon Chronicle supernova evidence is properly accredited.

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3. 3. Postman1 in reply to Laroquod 04:53 PM 6/29/12

   Laroquod _ Thank You! As soon as I read this, I started looking for that first article. I knew I had read that. Let's give credit where credit is due. I wonder if J. Allen reads SA?

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4. 4. Wayne Williamson 05:16 PM 6/29/12

   I wonder if Hubble could see anything in that area or maybe it already has and just wasn't associated with this event.

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5. 5. jtdwyer 10:36 PM 6/29/12

   It's been pointed out on another blog that a user 'JustOK' posted the blog http://news.slashdot.org/comments.pl?sid=2893343&cid=40208359
   on June 04 @10:10AM, quoting the 774 A.D. entry of the Anglo Saxon Chronicles.
   
   This reference seems to have preceded the SA 'Mattuk'
   June 5 @04:12AM posting. Sorry for any confusion.

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6. 6. jtdwyer in reply to Laroquod 07:49 AM 7/2/12

   Thanks to your comment, Johnathan Allen has graciously acknowledged the two prior discoverers of the Anglo-Saxon Chronicles entry referring to the potential supernova candidate and is taking steps to see that they also receive appropriate recognition. Please see his comment posted on 2012-06-30 03:01 AM at http://www.nature.com/news/ancient-text-gives-clue-to-mysterious-radiation-spike-1.10898
   
   I also want to point out that, beyond simply commenting on a blog, Jonathan also wrote the very considered communication published in Nature. Thanks all!

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