  The Tunguska explosion occurred in the morning of June 30, 1908, in Central
Siberia, some 800 km NNW from Lake Baikal. It devastated the forested area of
2150 sq. km, flattening and scorching some 30 million trees. Before this, a
luminous body flew overhead in the cloudless sky. The air waves from the
explosion were recorded as far as in London. The object that flew that morning
over Siberia is usually designated the "Tunguska meteorite" or - more
cautiously - the "Tunguska space body" (TSB). Certainly, this body was
dangerous: the taiga was leveled over an area twice as large as New York City.
The whole number of Tunguska hypotheses reaches a hundred, or so. But few of
them have been built according to the standards of science and with due
consideration of empirical data. There is also a serious methodological problem
that is, as a rule, overlooked: the need to take into consideration all
empirical data and to reconstruct the Tunguska event before building any models
of it. Such a reconstruction is essential - since the consequences of this
event are many and varied. The main Tunguska traces may be grouped and listed
as follows: (a) material traces; (b) instrumental traces; (c) informational
traces. To be sure that a proposed theory is correct, the scientist must check
it against all the three types of Tunguska evidence. Having reconstructed the
Tunguska event with due attention to all the evidence, we have to conclude that
it could not have been an asteroid or a comet core. There seems to exist in
space another type of dangerous space objects, whose nature still remains
unknown.
