Dear listees
Interesting...
Mid 90s I saw a great documentary on PBS about that period of famine
and the decline of the Roman Empire, with scientific evidences that the
Krakatoa
volcano in Indonesia was the reason.
Ice cores, texts from the Vatican talking about almost 30 years of dust
in the atmosphere and blurred sun, (not just 2 years !)
Now we hear about the Halley Comet.
Maybe it was both of them... because when I read "there was a small volcanic
effect"... Krakatoa is a major volcano on Earth and its eruption at that
time was a major
one: scientists identified the huge lava field in the ocean surrounding the
Krakatoa.
Anyway, very interesting
have a great evening
Michael B.
--------------------------------------------------
From: "Ron Baalke" <[email protected]>
Sent: Wednesday, December 18, 2013 6:21 PM
To: "Meteorite Mailing List" <[email protected]>
Subject: [meteorite-list] Why Halley's Comet May Be Linked to Famine 1,500
Years Ago
http://www.space.com/24005-halleys-comet-linked-to-ancient-famine.html
Why Halley's Comet May Be Linked to Famine 1,500 Years Ago
By Mike Wall
space.com
December 18, 2013
SAN FRANCISCO - The ancients had ample reason to view comets as harbingers
of doom, it would appear.
A piece of the famous Halley's comet likely slammed into Earth in A.D.
536, blasting so much dust into the atmosphere that the planet cooled
considerably, a new study suggests. This dramatic climate shift is linked
to drought and famine around the world, which may have made humanity more
susceptible to "Justinian's plague" in A.D. 541-542 - the first recorded
emergence of the Black Death in Europe.
The new results come from an analysis of Greenland ice that was laid down
between A.D. 533 and 540. The ice cores record large amounts of
atmospheric
dust during this seven-year period, not all of it originating on Earth.
"I have all this extraterrestrial stuff in my ice core," study leader
Dallas Abbott, of Columbia University's Lamont-Doherty Earth Observatory,
told LiveScience here last week at the annual meeting of the American
Geophysical Union.
Certain characteristics, such as high levels of tin, identify a comet
as the origin of the alien dust, Abbott said. And the stuff was deposited
during the Northern Hemisphere spring, suggesting that it came from the
Eta Aquarid meteor shower - material shed by Halley's comet that Earth
plows through every April-May.
The Eta Aquarid dust may be responsible for a period of mild cooling in
533, Abbott said, but it alone cannot explain the global dimming event
of 536-537, during which the planet may have cooled by as much as 5.4
degrees Fahrenheit (3 degrees Celsius). For that, something more dramatic
is required.
Ice core data record evidence of a volcanic eruption in 536, but it almost
certainly wasn't big enough to change the climate so dramatically, Abbott
said.
"There was, I think, a small volcanic effect," she said. "But I think
the major thing is that something hit the ocean."
She and her colleagues have found circumstantial evidence of such an
impact.
The Greenland ice cores contain fossils of tiny tropical marine organisms
- specifically, certain species of diatoms and silicoflagellates.
An extraterrestrial impact in the tropical ocean likely blasted these
little low-latitude organisms all the way to chilly Greenland, researchers
said. And Abbott believes the object responsible was once a piece of
Halley's
comet.
Halley zooms by Earth once every 76 years or so. It appeared in Earth's
skies in A.D. 530 and was astonishingly bright at the time, Abbott said.
(In fact, observations of Halley's comet go way back, with research
suggesting
the ancient Greeks saw the comet streaking across their skies in 466 B.C.)
"Of the two brightest apparitions of Comet Halley, one of them is in 530,"
Abbott said. "Comets are normally these dirty snowballs, but when they're
breaking up or they're shedding lots of debris, then that outer layer
of dark stuff goes away, and so the comet looks brighter."
It's unclear where exactly the putative comet chunk hit Earth or how big
it was, she added. However, a 2004 study estimated that a comet fragment
just 2,000 feet (600 meters) wide could have caused the 536-537 cooling
event if it exploded in the atmosphere and its constituent dust were
spread
evenly around the globe.
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