I suddenly saw that directly to the North, over Onkoul's Tunguska road, the sky split in two and fire appeared high and wide over the forest (as Semenov showed, about 50 degrees up - expedition note). The split in the sky grew larger, and the entire Northern side was covered with fire. At that moment I became so hot that I couldn't bear it, as if my shirt was on fire; from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, and I was thrown a few yards. I lost my senses for a moment, but then my wife ran out and led me to the house. -- Eyewitness report by S. Semenov

100 years ago this week, the sky exploded.

At 7:17 A.M. local time on June 30, 1908, a meteor (or possibly a fragment of a comet) entered earth's atmosphere somewhere above the lower region of the Stony Tunguska River in Siberia. The object, which may have been several tens of meters across, burst in the atmosphere, creating an explosion as much as 1,000 times more powerful than the atomic bomb that was dropped on Hiroshima.

Yet for decades, no one knew what exactly happened.

Some of the most popular theories include the crash or mid-air explosion of a UFO, a wandering black hole, a spontaneous nuclear fusion, and the end of the world (a theory that disproved itself by virtue of the fact that the world is still here).

Thanks largely to the questions surrounding Tunguska, the event has fueled stories by science fiction writers for most of the last century.

Just a sampling of the popular science fiction media that uses the Tunguska event as a plot element include:

  • In this summer's blockbuster Indiana Jones and the Kingdom of the Crystal Skull, it is hinted that the Tunguska event was the crash of an alien ship.
  • Popular video games including Area 51, Destroy all Humans! 2, and The Call of Cuthulu, describe the Tunguska event as the work of alien beings.
  • In Spider Robinson's popular Callahan series, the explosion is said to be the result of a test run for a death ray invented by scientist Nicola Tesla.
  • In “Donald Duck” comics, the event is blamed on the work of a mad scientist who is trying to invent gold.
  • The novel Timeline theorizes that the explosion was caused by time travelers sent back to hide evidence of research into time travel.
  • In his series, The Dresden Files, Jim Butcher explains Tunguska as having been the work of Ebenezar “Blackstaff' McCoy, of the White Council.

Tunguska has also been featured in work by noted science fiction writers - Arthur C. Clarke, Larry Niven and Isaac Asimov, to name a few.

Today, scientists study Tunguska when they think about asteroid deflection strategies. But it wasn't until 1930 that the first scientific inquiry into the event even took place. Once you factor in the remote Siberian location of the event, the Great Depression, two world wars, and the Soviet secrecy during the Cold War, the resulting lack of data surrounding Tunguska all helped to make it a darling of conspiracy theorists and science fiction writers alike.

And while many scientists have closed the book on the mystery of Tunguska, those with a more romantic mind may question the events surrounding the blast for another hundred years.