On June 30th, 1908, at dawn, a mysterious explosion took place in an almost uninhabited region of central Siberia. The explosion leveled 2000 km2 of taiga, uprooting about 80 million trees, which were left lying on the ground, away from the central point of the event, like the spokes of a wheel. The most probable theory considers the event as the impact of a meteorite or comet, although nobody could find the debris. Unlike other cases, as the Arizona Meteor Crater, no crater was found in the place of the event. As an explanation of these anomalies, it was concluded that the explosion of the celestial body took place at a high altitude (between 5 and 10 km). Taking into account the effects, it has been calculated that the energy released by the explosion would be in the span of 3 and 30 megatons. Recall that the most powerful nuclear weapon ever detonated (by the Soviet Union) was a 50 megatons hydrogen bomb, over 1000 times stronger than the Hiroshima bomb, which only released 20 kilotons. (One megaton equals 1000 kilotons). During the cold war, the Soviet Union boasted of possessing an even larger bomb (100 megatons) that they couldn’t use in Europe, as the effects of its explosion would reach their own territory.
|Trees knocked over by the Tunguska event|
If the Tunguska event had taken place in an inhabited area, instead of Siberia, its effects would have been catastrophic. If it had happened on top of New York City, the whole city and most of the surrounding country would have been devastated. Actually, as it took place in an uninhabited area of Siberia, there were no official casualties, although two dead persons are mentioned unofficially.
According to calculations, the diameter of the meteorite or comet that caused the Tunguska event would have measured between 150 and 200 meters, which means that it was small. Although comparisons are difficult, it has been estimated that the meteorite whose impact caused the Chicxulub crater and the corresponding global extinction of big dinosaurs, among many other species, would have measured about one km in diameter, therefore its mass would be at least 200 times greater. Assuming that its relative velocity to the Earth was the same, the power of that impact would have surpassed 2000 megatons. In addition, as that body impacted the Earth, the effects of the blow were much greater, for a huge amount of dust was thrown up to the atmosphere.
As was to be expected, the mysterious Tunguska event sharpened the imagination of writers of science fiction novels, who soon hypothesized that it had been caused by the explosion of an extraterrestrial ship. If I am not mistaken, Alexander Kazantsev was the first to propose this solution to the problem in a novel published in 1940 (Burning island). Kazantsev wrote several additional short stories on the same subject, as A visitor from outer space and The Martian, both published in 1946 and later translated into Spanish and English. In the first of these two short stories, he claims that the ship in question came from Mars to get water for its impoverished planet, but its crew lost control and the ship’s atomic engines exploded, causing the event. Kazantsev’s stories, especially A visitor from outer space, are so detailed, that many people (perhaps even the author himself) took them literally, as if their plots were real, rather than science fiction.
The idea was taken by other writers in the field. In 1951 Stanislaw Lem (now famous for his novel Solaris) published one of his first science fiction novels, The astronauts, that explains the Tunguska event as the result of the explosion of a ship coming from planet Venus. Other classic authors, such as Isaac Asimov and Arthur Clarke, also mention the event in some of their stories. A few resort to even more exotic causes, such as antimatter, black holes, time travel, or a space-temporal anomaly that would cause some of the effects of the Chicxulub asteroid to emerge today. Interestingly, the authors of this genre seem to have a fixation with Nikola Tesla, who is blamed of the accident in several stories, as a result of a failed experiment.
One of the most original versions was written by the brothers Arkady and Boris Strugatsky, who in their novel Monday begins on Saturday (1964) combine the motives of the alien ship and time travel, claiming that the exploding vehicle was moving backwards in time. That was the reason why the debris of the ship were not found, for they should have been sought in the past (in other words, they would only be visible before June 30th 1908).