Show Notes, John Glass PhD, 85.

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Impact Moon 1178AD: What did Canterbury’s Medieval Monks See?

 by Andy Fleming

If you take a look through binoculars at the Moon, you will be immediately reminded of the routine planetary violence that over billions of years up to today has shaped and moulded its familiar surface that we see today.  Unlike the Earth, however, the Moon has no plate tectonics, vulcanism or weathering, and its surface provides a pristine record of its impact history. Moreover, its recent history includes supplementary written records of events on the lunar surface.

Moon_by_Johannes_hevelius_1645In 1178, the chronicler Gervaise of Canterbury Abbey in England took down the depositions of five monks who had claimed to have seen a strange spectacle on the lunar surface. It read:

“This year on the 18th of June, when the Moon, a slim crescent, first became visible, a marvellous phenomenon was seen by several men who were watching it. Suddenly, the upper horn of the crescent was split in two. From the midpoint of the division, a flaming torch sprang up, spewing out over a considerable distance fire, hot coals and sparks. The body of the Moon, which was below writhed like a wounded snake. This happened a dozen times or more, and when the Moon returned to normal, the whole crescent took on a blackish appearance”.

18monk2bIn the journal Meteoritics in 1976, professional New York astronomer Jack Hartung investigated the claim, eventually putting forward the hypothesis that what the monks had witnessed was a meteor impacting the Moon. Indeed, Gervaise’s account, if true, is unique. There is no other account either in antiquity or during modern times of such a large lunar impact and resultant explosion. That the monks of Canterbury witnessed something is fairly certain, and Gervaise was clear that they were prepared to place their reputations on the line. Certainly, on the date in question the Moon was in the sky, revealing itself as a thin crescent.

imagesHartung’s hypothesis can be tested. Scientists have calculated that, given the naked-eye description of the event, a crater of at least 10 kilometres in diameter would have resulted, with long ejecta rays. A candidate crater was soon found in the expected location: Giordano Bruno, a crater named after the 16th-century astronomer and philosopher. At favourable times it can be observed with an ordinary telescope and is approximately 20 kilometres in diameter.

So is Giordano Bruno crater 832 years old? Interestingly, no one is certain about its age. The usual dating method certainly suggests this is a young crater, anywhere from centuries to about ten million years old.

There are, however, objections to Hartung’s hypothesis. Such an impact on the Moon should have showered the Earth with secondary meteorites in a fantastic firework display. And yet there are no records in European, Chinese or Arab chronicles of such a ferocious and stunning meteor storm.

In 2008, a further survey analysing high-resolution images of the crater and its surrounding area, estimated that it formed more than one million years ago ruling out the hypothesis of Hartung. The controversy will finally be put to rest when radiometric age-dating of impact-melt rocks at the crater is returned by the next generation of lunar explorers.

Whatever the monks of Canterbury saw on that warm summer June evening in 1178AD, whether it was an impact on the Moon, or a meteor exploding in the Earth’s upper atmosphere, it certainly must have been  a spectacular sight.


Guest John Glass

glassprofileJohn Glass has a Ph.D. in Sociology and currently teaches at Collin College as a Professor of Sociology. He is a committed advocate of the use of the scientific method to discover and understand the properties of the material and human world. He has been interested in the UFO phenomenon since childhood. He is unsure what to think about it, other than noting the volume of reports about the phenomenon. He adheres to the standards of evidence that correspond with the application of the scientific method and as such have no conclusions about if the UFO phenomenon is. John finds all aspects of the phenomenon fascinating, however.

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