[meteorite-list] Astronomers Suggest Comet To Blame for 6th-Century 'Nuclear Winter'

From: Bernhard <rendelius_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:20 2004
Message-ID: <008601c3ea7b$a0aa53e0$0100a8c0_at_rpgdothome>

I mean, do they offer some PROOF for their theory? A "plume" is nothing
that would have gone unobserved by the eye (left alone a comet exploding
in the sky) - and as much as I know, the "mini ice age" at that time
wasn't a global occurence, but rather a european one - at least to my
knowledge. There has been a second "mini ice age" around 1500 in Europe,
and this is either attributed to the Maraunder solar minimum or the
change of the gulf stream.

Bernhard

-----Original Message-----
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Subject: [meteorite-list] Astronomers Suggest Comet To Blame for
6th-Century 'Nuclear Winter'




Contact: Dr Derek Ward-Thompson derek.ward-thompson_at_astro.cf.ac.uk
029-2087-5314
Cardiff University
February 3, 2004

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Historical references from this period - known as the Dark Ages - are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.

                                     ###


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Received on Tue 03 Feb 2004 12:31:53 PM PST