Over 770 square miles of forest were leveled in an instant by a mysterious explosion in Siberia on this day in 1908. The blast occurred more than three miles above the earth’s surface near the Tunguska River; there was no crater, but thousands of trees had been reduced to tiny splinters across a giant, circular swath of land. The cause remains uncertain (and likely always will be), but it was most definitely not some kind of industrial disaster or secret military project. The most popular explanation in the scientific community nowadays is a little more outlandish than that.
It would take nearly two decades before someone would even see the blast site; Siberia is vast and hard to navigate, even now, and large parts of it have barely been explored. Coming across the bog strewn with needles of wood must have been eerie and hard to explain. But when investigators started asking questions, eyewitnesses reported seeing a huge fireball in the sky from as far as 500 miles away. They said the earth shook, and that a blast of hot air followed that was so strong as to shake buildings and knock people to their feet. It sounds like science fiction — but a review of European seismographs showed that there had indeed been some unusual, and strong, vibrations in the area in 1908.
So what was the cause of this mysterious blast? We don’t know! The most popular theories, though, point toward something extraterrestrial like a comet or asteroid that came apart before hitting the planet’s surface. That would explain the bizarre sights, shockwaves, and the lack of a crater. A few miniscule fragments of rock found on the site hint at that possibility. If true, it would be an exceedingly rare phenomenon; those “impact events” only occur once every few hundred years.
