Tunguska Explosion

UFO aficionados have long claimed that the Tunguska event is the result of an exploding alien spaceship or even an alien weapon going off to "save the Earth from an imminent threat". This hypothesis appears to originate from a science fiction story penned by Soviet engineer Alexander Kazantsev in 1946, in which a nuclear-powered Martian spaceship, seeking fresh water from Lake Baikal, blew up in mid-air. This story was inspired by Kazantsev's visit to Hiroshima in late 1945.

Most scientists today believe that the Tunguska event was caused by an asteroid or a comet that heated so rapidly upon plunging into the atmosphere that it blew up some five miles above the surface with an explosive force of 10 to 15 megatons. But that conclusion is far too rational for Russians like scientist Yuri Lavbin, who heads the Tunguska Space Phenomenon public state fund. It was Lavbin who in July announced that he would lead an expedition to Siberia and stated, "We intend to find proof that not a meteorite but an extraterrestrial spaceship crashed with the Earth."

[T]he peasants saw a body shining very brightly (too bright for the naked eye) with a bluish-white light... The body was in the form of 'a pipe', i.e. cylindrical. The sky was cloudless, except that low down on the horizon, in the direction in which this glowing body was observed, a small dark cloud was noticed. It was hot and dry and when the shining body approached the ground (which was covered with forest at this point) it seemed to be pulverized, and in its place a loud crash, not like thunder, but as if from the fall of large stones or from gunfire was heard. All the buildings shook and at the same time a forked tongue of flames broke through the cloud. All the inhabitants of the village ran out into the street in panic. The old women wept, everyone thought that the end of the world was approaching.