by Dennis Stacy
On June 30, 1908, something exploded above the
Siberian taiga north of Lake Baikal, near the Tunguska (Stony) River,
devastating some 2000 square kilometers of heavy forest in a single
gigantic flash. Theories as to the origin of the so-called Tunguska
Event have generated numerous articles and several books. They range
from a large asteroid or comet, to a nuclear-fueled spaceship of
Photo Caption: Landsat image of Western
Amazon showing possible impact crater. Slightly to the left of center
of this image is a dark spot surrounded by a crater-like rim.
Now it appears something similar may have transpired in the equally
sparsely populated Brazilian jungle in 1930, according to a recent
article in the English science weekly, New Scientist (November
11, 1995, p. 12). [See also "Incident at Curucá," by Patrick
Huyghe in The Sciences (March/April 1996, pp.14-17)] The
Brazilian event was reported in some newspapers at the time, and was
even investigated by a Catholic missionary, Father Fidele d'Alviano,
who wrote a report for L'Osservatore Romano, the papal
newspaper. But d'Alviano's account had largely disappeared from view.
It was first cited in a 1931 paper by Leonid Kulik of the Soviet
Academy of Sciences, who initially investigated the Tunguska explosion,
and then again in a 1989 article in The Journal of the
International Meteor Organization by scientists Nikolai Vasilyev
and Gennadij Andreev, referencing Kulik's original citation.
British astronomer Mark Bailey, of the Armagh Observatory, backtracked
the reference to d'Alviano's original article, aided by two local
schoolboys, Damian Markham and James Scriven. Based on interviews with
eyewitnesses, d'Alviano describes the event and its consequences--it
happened at eight in the morning, August 13, 1930--in graphic style,
but omits many key details that would aid astronomers in ascertaining
origin. Hope is still held, though, as d'Alviano kept voluminous
diaries, which the Vatican still possesses, and which Bailey wants to
Shortly before the explosion along its border with Peru in northwestern
Brazil, says d'Alviano, the sun turned red and then the sky went
totally dark, followed by a rain of white ash and an ear-piercing
whistle. Then three fireballs streaked across the sky and exploded,
their rumblings heard hundreds of kilometers around. Months later, some
of the affected forest was still smoldering.
Bailey notes that three house-sized objects were probably involved,
resulting in a combined one-megaton explosion, or about a tenth of the
estimated energy released in the Tunguska Event. Whatever their cause
ó the Brazilian bombs occurred at the height of the annual
Perseids meteor shower ó such large scale invaders may be far
more common than we previously suspected, says Bailey, when coupled in
time with the earlier Tunguska explosion, perhaps ten times as common.
"The Earth may be subjected to three or four [such events] a century,"
As far as the twentieth century is concerned, then, that's two down and
perhaps two to go, which could certainly make for some
Millennium-ending or beginning fireworks. It seems patently unlikely
anyone is aiming these things, but here's hoping, if they are, that
they continue to target highly unpopulated areas as in the past.
Otherwise, we'll all read about it--except those directly impacted.
[March 1999 Postscript: Click here
for the fascinating abstracts from the 1998 Krasnoyarsk conference on
the actual 1908 Tunguska event.]