Astronomers unravel a mystery of the Dark Ages

Contact: Dr Derek Ward-Thompson derek.ward-thompson@astro.cf.ac.uk 029-2087-5314 Cardiff University

Astronomers unravel a mystery of the Dark Ages Undergraduates' work blames comet for 6th-century "nuclear winter" Scientists at Cardiff University, UK, believe they have discovered the cause of crop failures and summer frosts some 1,500 years ago – a comet colliding with Earth. The team has been studying evidence from tree rings, which suggests that the Earth underwent a series of very cold summers around 536-540 AD, indicating an effect rather like a nuclear winter.

The scientists in the School of Physics and Astronomy believe this was caused by a comet hitting the earth and exploding in the upper atmosphere. The debris from this giant explosion was such that it enveloped the earth in soot and ash, blocking out the sunlight and causing the very cold weather.

This effect is known as a plume and is similar to that which was seen when comet Shoemaker-Levy-9 hit Jupiter in 1995.

Historical references from this period - known as the Dark Ages – are sparse, but what records there are, tell of crop failures and summer frosts.

The work was carried out by two Cardiff undergraduate students, Emma Rigby and Mel Symonds, as part of their student project work under the supervision of Dr Derek Ward-Thompson.

Their findings are reported in the February issue of Astronomy and Geophysics, the in-house magazine of the Royal Astronomical Society.

The surprising result of the new work is just how small a comet is needed to cause such dramatic effects. The scientists calculate that a comet not much more than half a kilometre across could cause a global nuclear winter effect. This is significantly smaller than was previously thought.

Dr. Ward-Thompson said: "One of the exciting aspects of this work is that we have re-classified the size of comet that represents a global threat. This work shows that even a comet of only half a kilometre in size could have global consequences. Previously nothing less than a kilometre across was counted as a global threat. If such an event happened again today, then once again a large fraction of the earth's population could face starvation."

The comet impact caused crop failures and wide-spread starvation among the sixth century population. The timing coincides with the Justinian Plague, widely believed to be the first appearance of the Black Death in Europe. It is possible that the plague was so rampant and took hold so quickly because the population was already weakened by starvation.

You have to wonder how well modern civilization would stand up to something like that today.

Depends on who you mean by "we." Western civilization would be damaged beyond repair, as we know it now, but it would certainly survive in some context. Military bases in isolated regions, nuclear subs and other such well stocked and well coordinated entitys would maintain their technological sophistication.

Think of a well provisioned nuclear aircraft carrier, with machine shops, etc., and assume that it survives the initial impact. Joe suburb might be in big trouble, but after he runs around for a few weeks in rags playing survivor imagine what happens when the USS Ronald Reagan pulls into port and declares martial law?

Now, the poor schmucks in Rio or Delhi or Athens are screwed. Ironically the folks in the hills outside Karachi or in the hinterlands of Nepal, assuming their terrain isn't imolated in the blast zone, should be fairly well off, as they're used to making do and "roughing it" in "primative" conditions.

Moses’ Comet

Mike Baillie
Discovering Archeology, July/August 1999

Moses called down a host of calamities upon Egypt until the pharaoh finally freed the Israelites. Perhaps he had the help of a comet impact coupled with a volcano. A volcano destroyed the island of Santorini in the Aegean Sea (between today's Greece and Turkey) around the middle of the second millennium B.C. Researchers Val LaMarche and Kathy Hirschboeck suggest the volcano might be associated with tree-ring evidence for several years of intense cold beginning in 1627 B.C. Could that form the basis for strange meteorological phenomena recorded in the biblical book of Exodus?

In the book of Exodus, which describes events a few hundred kilometers from Santorini, we read of a pillar of cloud and fire, a lingering darkness, and the parting of the Red Sea. An enormous column of ash must have hung in the sky over the eruption (the Israelites’ “pillar of cloud by day and fire by night?”), and the volcano doubtless caused a tsunami, or tidal wave (which could have drowned a pharaoh's army). The Exodus story is traditionally dated to either the thirteenth or fifteenth century B.C. Those dates, however, depend ultimately on identifying the “Pharaoh of the Oppression,” and historians have never proven to which ruler that infamous title referred. Many biblical scholars will disagree, but I suggest that a seventeenth-century B.C. date is not impossible.

The argument can be bolstered. Equally catastrophic meteorological conditions are recorded in the Bible for the time of King David. Psalm 18, in reference to David, speaks of terrifying events: “Earth shook and trembled. The foundations of the hills moved and were shaken. ... Smoke ... fire ... darkness ... dark waters ... thick clouds of the skies ... hailstones and coals of fire.” On some chronologies, David is placed 470 years after the Exodus. The spacing between the two disastrous events recorded in Irish tree rings at 1628 and 1159 B.C. is 469 years. The Exodus story includes dust, several days of darkness, hail, dead fish, undrinkable water, cattle killed by hail, water breaking out of rocks, the earth opening, the sea parting as in a tsunami, and so on. Someone looking at the Exodus story and knowing descriptions of other distant volcanic effects might offer the possibility that the Israelites escaped from Egypt under the cover of a major natural catastrophe. There may be veiled references to comets in the biblical narrative, leading to the possibility that the Santorini eruption itself may have been triggered by a bolide (comet or asteroid) impact.

David Levy, co-discoverer of the comet that bears his and Jean Shoemaker's names, has argued that the description of the “angel of the Lord in the sky over Jerusalem with a drawn sword” (1 Chronicles 21) could be a reference to a comet. The Angel of the Lord was, of course, also present at the Exodus, as it was “traveling in front of Israel's army.” Further, there are indications that as the Israelites left Egypt, the night was as bright as midday. The nights over Europe were reported to have been daytime-bright after the only known modern bolide impact, the Tunguska explosion over Siberia in 1908.

These stories raise the question of whether comets recorded by the Chinese at the start and end of the Shang Dynasty, at very near the same dates, were the same as the comets that may be recorded in the Old Testament. I believe that we know the answer: In the last five millennia, several dynastic changes and dark ages have been the direct result of impacts and/or volcanoes. The consequences of such events must have been devastating, leading to apocalyptic imagery in religious writing and predictions of the end of the world. Zachariah of Mitylene lived through the environmental disaster that began about 540 A.D. In the mid-550s, he wrote in his twelve-volume records of the trials the world had survived: “In addition to all the fearful things described above, the earthquakes and famines and wars, ... there has also been fulfilled against us the curse of Moses in Deuteronomy."“ The curse included pestilence, consumption, fever, fiery blasts from the skies, mildew, a rain of powder and dust, and darkness. The curse of Moses must have seemed an appropriate description of life after the impact of a piece of a comet.

Excellent analysis, imo. I was thinking along the same lines. We (America) would survive it in some form, but no doubt greatly weakened. A large proportion of the population would die of famine and disease. Indeed, the only survivors might be those favored few who are fortunate enough to be rationed food (that would have to be grown on government run farms, which in turn would need an assist from artifical lighting to grow their crops). This is why it would be necessary to maintain the infrastructure. For the rest of us, it would be the law of the jungle.

Our science and technology would not be lost, however, in contrast to ancient civilizations. Still, it would be an unacceptable setback.

Just shooting from the hip, of course . . . In actuality, I can't possibly know what would happen. But as I said above, I think a space shield of some sort will be worthy of consideration soon, particularly if conclusive proof of this comet theory of civilization is uncovered.

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