Astronomy: Clue to an ancient cosmic-ray event?

Journal name:
Nature
Volume:
486,
Page:
473
Date published:
DOI:
doi:10.1038/486473e
Published online

It is tempting to speculate that the ancient text of the Anglo-Saxon Chronicle might offer a clue to the cause of the mysterious, dramatic cosmic-ray event in AD 774 (F. Miyake et al. Nature 486, 240242; 2012).

A chronicle entry for the same year (see go.nature.com/wwkw5j) hints at the presence of a supernova largely hidden behind a dust cloud, which would scatter and absorb all light bar a trickle of red. The resulting supernova remnant would be invisible.

The entry notes: “This year also appeared in the heavens a red crucifix, after sunset; the Mercians and the men of Kent fought at Otford; and wonderful serpents were seen in the land of the South-Saxons.”

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Affiliations

  1. University of California, Santa Cruz, California, USA.

    • Jonathon Allen

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Comments

  1. Report this comment #63501

    Ilya Usoskin said:

    This was a nice idea, indeed. However, as argued by Usoskin et al. (Asstron. Astrophys., 552, L3, 2013), the "red crucifix" was unlikely a supernova but most likely an aurora borealis, that supports the solar origin of the 775 AD event. As said by Usoskin et al. (2013):
    "We surveyed historical nova catalogues (e.g., Xu et al. 2000) but found no credible report of supernovae in the AD770s. Allen (2012) interprets the red cross (Anglo-Saxon Chronicle) as an
    exotic nearby supernova with an unobservable remnant, but we interpret this as an aurora. This is supported by a report that the same year ?snakes... seen extraordinarily in the land of the
    South-Saxons? (Swanton 2000). Serpents often feature in des criptions of aurorae (Dall?Olmo 1980), reflecting the sinuous movement of auroral structures. We also note the uncertain dating
    of these events in the Anglo Saxon Chronicle, with Swanton (2000) re-dating them to AD776, i.e., after the onset of the AD775 event. We do not directly associate any particular aurora with the 14C event, but a distinct cluster of aurorae between AD770 and AD776 suggests a high solar activity level around AD775."

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