Saturday, 25 June 2016

Gervase and the Moon in June

On 25th June 1178 five monks from Canterbury witnessed a curious astronomical event1:

“In this year, on the Sunday before the Feast of St John the Baptist, after sunset when the moon had first become visible a marvellous phenomenon was witnessed by some five or more men who were sitting there facing the moon. Now there was a bright new moo, and as usual in that phase its horns were tilted toward the east; and suddenly the upper horn 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. Meanwhile the body of the moon which was below writhed, as it were, in anxiety, and, to put it in the words of those who reported it to me and saw it with their own eyes, the moon throbbed like a wounded snake.”

The account can be found in the chronicles of Gervase of Canterbury, a medieval monk considered a reliable historian.

This extraordinary event was largely forgotten until 800 years later when, in 1976, the geologist Jack Hartung suggested Gervase had recorded a rare eye-witness account of the five monks who had seen an impact on the Moon's surface by a large meteor. The periodic bombardment of the Moon is a fate it has suffered regularly over its 4 billion year long history as attested by the many craters across its surface, but few of these impacts have been actually witnessed.

Hartung argued that evidence of the impact could be seen on the north eastern edge of the moon in a crater named after the 17th century Italian philosopher Giordano Bruno. Hartung suggested the flame the monks saw was incandescent gases, or sunlight reflecting on dust emitted from the crater. He argued that such a crater would be at least 7 miles across, possess bright rays extending for at least 70 miles formed by debris thrown out at impact, and be situated between 30 and 60 degrees North, 75 and 105 degrees East. The crater would be very near the edge of the Moon, or just on the far side. The Giordano Bruno crater happens to lie within these co-ordinates, 13 miles in diameter and notable for its brightness and the rays extending several hundred miles from it.2

The Giordano Bruno crater
Lunar astronomers Callame and Mulholland claim the event would have been sufficiently visible to justify the description of the eye-witness accounts recorded by Gervase. The astronomers also detected evidence of a small vibration in the orbit of the Moon. The Moon rotates in such a way that the face is always pointing at Earth, but with small oscillations, giving it a slight wobble about its polar axis. This slight wobble is not visible to the naked eye but has been detected by astronomers firing a laser beam at reflectors left on the Moon's surface by Apollo astronauts. When the laser is fired the arrival of the returning light beam is timed. Over the years thousands of laser beams have been fired at the Moon providing sufficient data to detect a 15 metre oscillation of the lunar surface about its polar axis over three years. This vibration,  Callame and Mulholland argue, can only be explained as the result of a significant recent impact of such a magnitude to have formed the Giordano Bruno crater. It is estimated that this vibration would die out over a period 20,000 year, or so.3

From studies of impact cratering it is possible to estimate the energy released at impact to have created the crater; the Giordano Bruno would have required around 100,000 megatons. By comparison, on 30th June 1908 a meteor is thought to have burst in mid-air at an altitude of 5 to 10 kilometres over Tunguska, Siberia. The detonation felled around 80 million trees over an area of over 2,000 square kilometres and would have been capable of destroying a large city if impacting on a populous area. Early estimates considered the energy release equivalent to 10–15 megatons, about 1,000 times greater than the atomic bomb dropped on Hiroshima, Japan in 1945.4

In 1975 seismometers left on the Moon by Apollo astronauts detected the impact of a huge swarm of boulders. The bombardment started on June 22, which suggests the Taurids were responsible for the onslaught.

Today many astronomers argue that the Giordano Bruno crater was created more than a million years ago but accept the wobble of the Moon's polar axis is the result of an interstellar impact. However, astronomers have argued that an impact of such magnitude to form the Giordano Bruno crater would have ejected more than 10 million tons of lunar debris, much of which, inevitably, should have rained down into the Earth’s atmosphere causing spectacular meteor storms lasting for many days after the impact. Yet, there are no reports of such an event in 1178.

Current thinking is that the monks probably observed a meteor exploding in the Earth's upper atmosphere travelling head-on toward them along the sight-line of one horn of the crescent Moon. The meteor would have exploded when it entered the upper atmosphere, creating the “hot coals and sparks”, obscuring the crescent with a dark smoke trail. Atmospheric turbulence would account for the “writhing snake” effect.

A head-on meteor in the Earth’s atmosphere would only align with the horn of the Moon over a small area of the Earth’s surface giving a localised perspective which may explain why only the five monks witnessed the impact and apparently no one else. Astronomer Duncan Steele has suggested that the meteor could have originated from the Beta Taurid meteor shower. This is a trail of debris from Comet Encke, which the Earth crosses every June. Clube and Napier, explain that, “the significant feature is not collision with comets themselves, but with their debris”.

Whether the astronomical event that the monks witnessed was the creation of the Giordano Bruno crater or a meteor exploding in the upper atmosphere, like the Tunguska event, it underlines the fact that the planets of the inner solar system are prone to periodic bombardment by space debris from comet trails with catastrophic consequences; such an event seems to have occurred during the Dark Ages.

Something Nasty in the Dark Ages?
A comet appeared in the sky early in 1066, which many interpreted as a premonition of the Norman conquest of England. The comet appears on the Bayeaux Tapestry, an embroidery depicting the Norman invasion and defeat of the English at the Battle of Hastings in 1066. This happened to be comet Halley, the first periodic comet detected, travelling past Earth once every 76 years or so. Observations of Halley's comet suggest the ancient Greeks observed the comet as long ago as 466 BC.

The Bayeaux Tapestry showing Halley's Comet
Geoffrey of Monmouth was probably aware of the comet recorded on the Bayeaux Tapestry and its implied meaning on the outcome on the Battle of Hastings. He writes of a comet in his History of the Kings of Britain (Historia Regum Brittaniae, c.1136), which foreshadows the reign of Uther. On the way to the battle Uther sees a comet in the shape of a fiery dragon, which Merlin interprets as a sign of Aurelius's imminent death and Uther's glorious future:

“At the appearance of this star, a general fear and amazement seized the people; and even Uther, the king's brother, who was then upon his march with his army into Cambria, [Wales] being not a little terrified at it, was very curious to know of the learned men, what it portended. Among others, he ordered Merlin to be called, who also attended in this expedition to give his advice in the management of the war; and who, being now presented before him, was commanded to discover to him the signification of the star. At this he burst out into tears, and with a loud voice cried out;

“O irreparable loss! O distressed people of Britain! Alas! the illustrious prince is departed! The renowned king of the Britons, Aurelius Ambrosius, is dead! Whose death will prove fatal to us all, unless God be our helper. Make haste, therefore, most noble Uther, make haste to engage the enemy: the victory will be yours, and you shall be king of all Britain. For the star, and the fiery dragon under it, signifies yourself, and the ray extending towards the Gallic coast, portends that you shall have a most potent son, to whose power all those kingdoms shall be subject over which the ray reaches. But the other ray signifies a daughter, whose sons and grandsons shall successively enjoy the kingdom of Britain'.” (BOOK VIII, CHAP. XV)

After winning the battle Geoffrey gives Uther the epithet “Pendragon”. Clearly Geoffrey misinterpreted “Pendragon” as meaning “dragon's head” (from the comet) whereas it literally means “Chief-Dragon” as “chief of warriors”. But, significantly, Geoffrey's tale of Arthur is set in the Dark Ages, so although he may have been inspired by the depiction of Halley's Comet on the Bayeaux Tapestry as an omen to the Battle of Hastings, he is clearly referring to a comet event in the days of the Great Arthur.

Astronomers believe there was an increased risk from bombardment in the period between 400 and 700 AD, the classic Dark Age period. Contemporary chroniclers write of a period of climate change, prolonged winters, decreased temperatures and a persistent dust veil. Gildas, writing around c.540 AD, describes a bleak picture of Britain at this time. Historians have long suspected a downturn in the Britons fortunes played to the invading Anglo Saxon's advantage. It was at this time that refortified post-Roman towns such as Wroxeter (Viroconium) were deserted.

The 5th century historian Zachariah of Mitylene writes of “a great and terrible comet appeared in the sky at evening-time for 100 days” around in around 538-9 AD. The medieval historian Roger of Wendover stated that, “in the year of grace 541 AD, there appeared a comet in Gaul, so vast that the whole sky seemed on fire. In the same year, there dropped real blood from the clouds, and a dreadful mortality ensued.

Some versions of the Welsh Annals open with the entry for 447 AD - “Days as dark as night”. A hundred years later in 547 The Welsh Annals record “great death [plague] in which Maelgwn, king of Gwynedd died. Thus they say 'The long sleep of Maelgwn in the court of Rhos'. Then was the yellow plague.” The Irish Annals record “a failure of bread” in 536 and 539 suggesting crop failure owing to climate change. Repeatedly, these events are followed by outbreaks of plague.

The Anglo Saxon Chronicle records that in the year 538 the sun was eclipsed, fourteen days before the calends of March, from before morning until nine and in 540 the sun was eclipsed on the twelfth day before the calends of July; and the stars showed themselves full nigh half an hour over nine.

The celestial disturbance appears to have continued for some time; later the Welsh Annals record “a star of marvellous brightness was seen shining throughout the whole world” in 676 followed by a great plague in Britain in 682, in which Cadwaladr son of Cadwallon dies. Then in 683 there was plague in Ireland. The Anglo Saxon Chronicle again mirrors the Welsh Annals; in 678 a comet-star appeared in August, and shone every morning, during three months, like a sunbeam. It was around this time that hillforts such as Cadbury were abandoned.

All of these Chronicle accounts concur on the appearance of a comet or celestial disturbances during the period around 400 – 700 AD. This dramatic Dark Age event is linked to climate change, drought and famine around the world. This severe downturn in living conditions left humanity more susceptible to outbreaks plague; the “Justinian Plague” arrived in Constantinople in 542 AD, the first recorded emergence of the Black Death in Europe.

It has long been suspected that around this time Britain was devastated by the effects of a cometary impact, an event occurring in 536 AD which produced a dust veil and cooling effect with global consequences.

Volcano or Comet?
The cause of this catastrophic event in the Dark Ages that resulted in crop failures, summer frosts, drought and famine around the world some 1500 years ago has puzzled historians and scientists alike for years.

Author David Keys argues that evidence from historic sources refer to a persistent dry fog across the Mediterranean, that lasted for 12 to 18 months and caused “a spring without mildness and a summer without heat”.Keys believed that a major volcanic event was to blame and suspected Krakatoa as the culprit.5

The same year Mike Baillie argued that comet symbolism underlies the Arthurian Legend. Baillie developed the science of dendrochronology, or tree-ring dating, finding evidence around the world for dramatic effects in trees across the years from 536 to 545 AD. Significantly, Baillie concludes,  a close comet pass coincides precisely with the time the Welsh Annals stated that Arthur perished in the strife of Camlann, 537AD.6

Dallas Abbott, of Columbia University, has recently studied the 536 AD event and the consequent dust veil and combined planetary cooling effect. After taking deep-core samples from Greenland ice that was laid down between 533 and 540 AD, they found evidence of a volcanic eruption in 536 AD but it almost certainly was not of a sufficient magnitude to cause such dramatic climate change.

The Greenland ice cores were also found to contain fossils of tiny tropical marine organisms suggesting this was an extraterrestrial impact in a tropical ocean, throwing them high into the stratosphere, carrying them to the north polar regions. The ice cores also contained large amounts of atmospheric dust from this seven-year period, not all of it originating on Earth but some particles indicative of an extraterrestrial source.

This cometary residue apparent in the ice cores contained deposits of tin, nickel and iron oxide spherules, which Abbott explains, are associated with cometary dust. This alien matter was deposited in Greenland during the Northern Hemisphere spring time, coinciding with the Eta Aquarid meteor shower.

The orbit of comet Halley leaves a trail of debris which the Earth’s crosses every year on two occasions: the Eta Aquariids in early May, and the Orionids in late October. Abbott argues that although the Eta Aquarid dust may be responsible for a cooling period in 533 AD, on its own it cannot explain the global dimming effect of 536-7 AD which cooled global temperatures by as much as 3 degrees Celsius (5.4 degrees Fahrenheit) for several years; that would require something much more dramatic. Abbott concluded that a piece of the famous Halley's Comet broke away from the main body and impacted on Earth in 536 AD blasting so much dust into the atmosphere that the planet cooled considerably.7

Halley's Comet 1986
Halley's Comet is known to have appeared in Earth's skies in 530 AD and was noted as being astonishingly bright at that time. Irish Annals record “running stars” that were shining for 20 days, and there were many earthquakes. Both China and Byzantium recorded in 530 AD that Halley’s Comet continued to shine for 20 days. The brightness suggests a close pass in which the comet may have broken up as it passed Earth and rounded the sun, ejecting large pieces that fell to Earth and leaving a thicker than normal trail of debris responsible for the dust veil of 536 AD and cooling effect of subsequent years. In 2004 a study estimated that a comet fragment just 2,000 feet (600 metres) wide could have caused the 536 AD event.

Unlike the event recorded by Gervase in 1178, which is doubted as a significant lunar impact by many astronomers today, the 536 AD dust veil and its global consequences is an accepted event; yet few reconstructions of Dark Age History acknowledge the event as a contributory factor in the decline of the Britons.

Halley's Comet's most recent appearance was in 1986. Its next appearance will be in 2061.

Updated 26/06/16
Edited 29/06/16

Copyright © 2016 Edward Watson 

1. The date of the event was originally recorded as 18th June on the Julian calendar which converts to 25th June in the modern Gregorian scheme.
2. Victor Clube and Bill Napier, The Cosmic Winter, Basil Blackwell, 1990. pp.159-162.
3. Ibid.
4. Modern estimates claim that the airburst had an energy range from 3 to 5 megatons.
5. David Keys, Catastrophe: An Investigation into the Origins of the Modern World, Century, 1999.
6. Mike Baillie, Exodus to Arthur, Batsford, 1999.
7. However, observations taken from Halley’s last appearance in 1986 suggest that the Eta Aquarid meteor shower might not originate from Halley’s Comet, but is possibly disturbed by it.

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1 comment:

  1. Study shows risk of Taurid meteor swarm
    According to Western Meteor Physics Group data analysis, the Earth will approach within 30,000,000 km of the centre of the Taurid swarm during the summer of 2019, the closest such encounter since 1975.
    >> Study shows risk of Taurid meteor swarm


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