Interesting variation on the old "asteroid hitting the earth" problem
in the Independent:
http://news.independent.co.uk/world/science_medical/story.jsp?story=487550<snip>
A collision between Earth and a passing comet in the 6th century AD
may have caused the collapse of agriculture, mass famine and
indirectly led to the bubonic plague in Europe, a study has suggested.
...
Studies of tree rings - from preserved oaks retrieved from Irish bogs
to ancient American pine trees - have shown that plant growth around
the world almost stopped between about 536AD to 545AD. Chinese records
from this time refer to a "dust veil" obscuring the skies.
Mediterranean historians record a "dry fog" that blocked out much of
the sun's heat for more than a year.
...
"A comet less than 1km in diameter has not been previously considered
to represent a global hazard - as opposed to a local hazard - let
alone one 0.5km across," he said.
<snip>
All we need now is a suitable sized chunk of rock to make an inbound
visit coinciding with GWB's religious mania and we will be well and
truly back in the Dark Ages again ... rapture that one Georgie ...
Nihil