In the morning of June 30, 1908, the ground trembled in Central Siberia, and a series of flying fireballs, causing a “frightful sound” of explosions, were observed in the sky above the Stony Tunguska River. Strange glowing clouds, colorful sunsets, and a weak luminescence in the night were reported as far as Europe.
Likely many thousand people in a radius of 1.500 kilometers (or 900 miles) observed the Tunguska Event. However, due to the remoteness of the affected area, eyewitness testimonies were collected only more than half of a century after the event, and most were second-hand oral accounts. In 2008, unpublished material collected by Russian ethnographer Sev’yan Vainshtein resurfaced, including some first-hand accounts of the event.
Despite its notoriety in pop-culture, hard scientific data covering the Tunguska Event is sparse. Since 1928 more than forty expeditions explored the site, taking samples from the soils, rocks, and even trees, with ambiguous results. Some seismic and air-pressure wave registrations survive, recorded immediately after the blast, and surveys of the devastated forest mapped some thirty years later.
Based on the lack of hard data, like a crater or a meteorite, and conflicting accounts, many theories of widely varying plausibility were proposed over time.
At the time of the event, international newspapers speculated about a volcanic eruption. Russian scientists, like Dr. Arkady Voznesensky, Director of the Magnetographic and Meteorological Observatory at Irkutsk where seismic waves of the explosion were recorded, speculated about a cosmic impact. In 1927, Russian mineralogist Leonid Alexejewitsch Kulik of the Russian Meteorological Institute, explained the event as the mid-air explosion of a meteorite, explaining the lack of an impact crater on the ground. In 1934, Soviet astronomers, based on Kulik’s work, proposed that a comet exploded in