From mcmahon@maple.lemoyne.edu Sun Sep 10 11:02:13 2000
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Date: Sun, 10 Sep 2000 14:05:12 -0400 (EDT)
From: John McMahon <mcmahon@maple.lemoyne.edu>
Subject: "Dark Ages" and Comet Biela
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	I did a little poking around concerning the comet
	mentioned in the *Times* piece as being associated
	with the events leading to "dark ages." Comet Biela
	is/was a very interesting phenomenon, but references
	to it -- and its very "discovery" -- are quite recent.
	In fact it was only in the latter part of the 18th 
	and the first part of the 19th c. that the object was "discovered"
	and its seven-year period actually established. It was
	the comet's namesake, Wilhelm von Biela, who finally
	was able to link the previous appearances and to declare
	it officially as a new periodic comet in 1826. The comet,
	however, seems to have been quite unstable, and in its return
	of 1846 two nuclei were observed. It was later determined 
	that they were 1.6 million miles apart during that approach.
	The next approach (1852) afforded poorer views because of
	the Sun's glare, and the 1859 return was little better. It
	was unseen in the 1865-6 approach and seems to have broken
	up completely. In its place, however, strong meteor showers
	appeared in the latter part of the century, known as
	the Bielids or the Andromedids, from the constellation
	in which their radiant point is located. Today these
	are relatively sparse with various peak years, a
	result of the comet's debris path being affected by
	the planet Jupiter.

	More info at:

	http://www.maa.mhn.de/Comet/Shower/andromedids.html

	http://comets.amsmeteors.org/meteors/showers/andromedids.html

	(In passing, I might note that Comet LINEAR, visible
	earlier in the summer, broke up in late July. Barely
	at naked eye brightness (c. mag 5.7) I was fortunate
	enough to have observed it several times telescopically
	up to a few days before its demise. It was no Hale-Bopp,
	and whether any meteors will be associated with it
	remains to be seen since it was a first-time solar
	system visitor.)

	Folks on the History of Astronomy list (HASTRO-L)
	have passed on other info that may be of interest:

	"On a Great Meteor Shower of the Year 524 A.D., and its Probable
	Connection with the Comet of Biela", by W. Klinkerfues (*Popular
	Astronomy*, Vol. 39 [1931]: 573-583). For other references to 
	comet Biela see:

	http://www.imo.net/bib/combie0.html

	Reviews of Michael Baillie's *Exodus to Arthur:
	Catastrophic Encounters with Comets* (London: Batsford, 1999):

	http://www.britarch.ac.uk/ba/ba46/ba46book.html

	http://abob.libs.uga.edu/bobk/ccc/cc010899.html

	http://www.szoraster.com/Science/Exodus%20to%20Arthur.htm

	Also noted: David Keys, *Catastrophe, the Day the
	Sun Went Out* (recently published). According to one HASTRO
	lister, it appears that Keys focusses on circa 540 A.D.

	John McMahon
	Le Moyne College
	mcmahon@maple.lemoyne.edu

.