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On June 30, 1908, an extraordinary explosion occurred in the Russian skies above modern-day Evenkia, Siberia, with repercussions that continue to both fascinate and frustrate legitimate scientists and fringe theorists alike. The so-called "Tunguska Event" or "Tunguska Blast" (so named for the rural region near the Stony Tunguska River devastated by the explosion) has since become famous among both astronomy aficionados and conspiracy theorists, often blurring the line between science fiction and science fact.
Let's start, then, with the facts. Estimates vary on the actual force of the Tunguska explosion—by a rather significant range of between 10 and 40 megatons. Like any good explosion, witnesses saw—and felt—a massive fireball 60 kilometers away, and a shockwave caused recorded damage at even greater distances, rattling some of the few seismographic sensors of the era in Jena, Germany—more than 5,000 kilometers away.
Astronomers across Europe reported occluded sky conditions consistent with some measure of dust fallout from a massive explosion. Rare noctilucent ("night-shining") clouds caused the skies above Europe to glow in the nights following the blast, and meteorologists as far away as North America reported unusual atmospheric pressure disturbances.
Given all this available data, the scientists of the day should have been able to discern precisely what occurred in Tunguska. The only problem is that no one outside of Siberia knew that anything had happened in Siberia, because the region was so sparsely populated—and the political climate so chaotic—that word of the blast didn't immediately travel to the outside world.
Thanks to World War I and the Russian Revolution, a formal investigation of the Tunguska Blast didn't occur until 1927—almost two decades after the fact.
When mineralogist Leonid Kulik finally began the investigation, he went in search of an assumed meteorite impact. However, Kulik was shocked to discover a region of trees still lying flat from the explosion—but no impact crater.
This was something different, and unexplained, and only murky facts exist to help clear the picture. It's little wonder that the Tunguska Event immediately became the subject of speculation—and from there, science fiction took hold.
WHO WAS THE FIRST KNOWN SCI-FI WRITER TO FICTIONALIZE THE CAUSE OF THE "TUNGUSKA BLAST"?
Who was the first known science-fiction writer to fictionalize a possible explanation of the famous (and infamously unexplained) "Tunguska Blast" of 1908?
That dubious honor goes to the all-but-unheard-of Soviet engineer-turned-writer Aleksander Kazantsev, who advanced the notion that a nuclear-powered Martian spacecraft exploded above Tunguska in his 1946 sci-fi story. The inspiration for Kazantsev's story was the engineer's own observations of the Hiroshima fallout in 1945, where he noted the striking similarities between the felled trees of Tunguska and the flattened buildings of the Japanese damage swath.
While it was the nuclear angle that brought Kazantsev's story some notice in the 1940s, it's the notion of an above-ground explosion that's kept it in discussions ever since. The theory of an airborne explosion explained the lack of an impact crater.
Moreover, when the Kulik expedition finally reached the Tunguska blast epicenter in 1927, the mineralogist noted a group of trees at the center of the damage area that remained standing straight up, while everything around them lay pressed flat in an expansive butterfly-wing pattern.
These trees were likely directly beneath the aerial explosion, with the downward force holding them in place, rather than flattening them. All other speculations aside, an airborne detonation is perhaps the sole aspect of the Tunguska Event upon which all parties can agree.
While conspiracy theorists still hold to many wild explanations for the Tunguska Event—including the explosion of an alien spacecraft—scientists have largely divided into two camps of theories: the comet or the meteorite.
Studies have found gaseous traces of nickel and iridium in the geological record that almost certainly indicates the detonation of an extraterrestrial object above Tunguska at the place and time in question, but a lack of corroborative geological evidence has left many astronomers and physicists at a loss to decide between the explosion of an icy comet nucleus or the total incineration of a conventional stony asteroid.
As for Kazantsev, science has embraced his aerial suppositions, even if the world has all but forgotten him and his story. Still, if imitation is the sincerest form of flattery, Kazantsev could take heart: In 1951, a far more famous sci-fi scribe—Stanislaw Lem—suggested that the Tunguska blast was the fallout from a spacecraft explosion, but Lem's space travelers were from Venus.
The Quibble of the Week
If you uncover a questionable fact or debatable aspect of this week's Geek Trivia, just post it in the discussion area of the article. Every week, yours truly will choose the best post from the assembled masses and discuss it in the next edition of Geek Trivia.
This week, we have the rare quibble of a quibble, with a reader disputing The Quibble of the Week component from the Nov. 3 edition of Geek Trivia, "Pretty as a pixel." Here's how TechRepublic member D.ajit explained the issue.
"My quibble is about the quibble [that] says that 10 MHz is supersonic. Supersonic always means faster than the speed of sound, and subsonic means below. Sound frequencies above the human threshold of hearing are… ultrasonic. Those below the lower threshold are correctly called 'subsonic frequencies'—and not just subsonic."
The Trivia Geek, also known as Jay Garmon, is a former advertising copywriter and Web developer who's duped TechRepublic into underwriting his affinity for movies, sci-fi, comic books, technology, and all things geekish or subcultural.
Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger — amusing and abusing IT pros. Read his full profile. You can also follow him on his personal blog.