[meteorite-list] Tunguska Event Part 1 of 2

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:48:14 2004
Message-ID: <3BDD3F73.8618F4D6_at_lehrer1.rz.uni-karlsruhe.de>

almitt wrote:

> I'll leave the Tunguska event to someone else.

Sky and Telescope, December 1978, pp. 497-498:

The Tunguska Event and Encke's Comet

Just what was it that collided with the earth on June 30, 1908, in
central Siberia? A dazzlingly bright daytime fireball was seen, and
over the site of its fall flames and a cloud of smoke appeared.
Deafening explosions were heard at distances up to 1,000 km and
were recorded on seismographs and barographs. To quote Lubor
Kresak of the Slovak Academy of Sciences:

"Hundreds of articles written on the unique Tunguska event of June
30, 1908, offer a variety of competitive explanations. Apart from
the obvious fictions and speculations lacking [in] scientific
objectivity (alien spacecraft, nuclear explosion, antimatter,
black hole), every known type of interplanetary body crossing the
orbit of the Earth has been suggested as the impacting object. The
candidates include a small asteroid - or unusually large meteorite
- ranging in composition from meteoric iron (Yavnel', 1957), to pre
-type I carbonaceous chondrite (F.L. Whipple, 1967), and a small
comet, extinct or active, with a dust tail (F.J.W. Whipple, 1930;
Fesenkov, 1961 and 1966)." Writing in the Bulletin of the Astronomical
Institutes of Czechoslovakia, Dr. Kresak presents strong grounds for
surmising that the Tunguska object was in fact a fragment of Comet
Encke, separated from it thousands of years ago. He begins by noting
that although the impact energy seems to have been comparable to that
expended in forming Arizona's Meteor Crater, no sizable crater was
formed in the heavily damaged Tunguska area. This point favors a low-
density impacting body. The only direct evidence concerning the orbit
of the object before it entered the atmosphere is the position of its
apparent radiant in the sky. The radiant was only about 20° from the
direction of the earth's orbital motion. Thus the event was either a
head-on collision of the earth with an object in retrograde motion
(such as a long-period comet) or an object near the aphelion point
of a direct orbit (Apollo-type asteroid or daylight meteor stream).
Received on Mon 29 Oct 2001 06:37:23 AM PST