What was the Tunguska Event?
Young forrest at the site of the tunguska meteorite explosion nearly a century after the event, siberia, russia, 2008. Source: (Sovfoto/UIG via Getty Images)
On June 30, 1908, around 7:14 AM, an explosion one thousand times more powerful than the atomic bomb dropped on Hiroshima occurred near the Podkamennaya Tunguska River in Siberia. Witnesses reported seeing a fireball on the horizon followed by tremors and hot winds forceful enough to blow people down and cause buildings to tremble. Seismic waves were strong enough to be recorded in western Europe. The blast could be seen as far as five hundred miles away and gases were released into the atmosphere which caused the nighttime sky to appear brighter afterward.
The cause of the explosion has been a topic of debate ever since. It was initially thought to be a meteorite impact or volcanic explosion; however, investigations at the time were hindered by the inaccessibility of the area as well as the political situation in Russia at that time. However, that didn’t stop scientists from trying to unravel the mystery. The first scientist to investigate the site was Russian mineralogist Leonid Alekseyevich Kulik who read newspaper articles about the explosion thirteen years after it occurred. Convinced the explosion was caused by a meteorite and hoping to recover extraterrestrial metals from the site, he traveled to Kansk and began reading up on the event.
He traveled to the remote outpost of Wanawara in March of 1927 and the following month discovered the impact site, a scorched 820-square-mile area consisting of more than eighty million flattened trees lying in a circle. The trees all pointed away from the epicenter, which was the area immediately below the explosion, in which Kulik’s team found not a single large crater but rather a marshy bog. They did, however, find several circular pits which they identified as craters produced by fragments of the meteorite. Unfortunately, they weren’t able to locate any of the fragments and could only conclude that they had been lost in the bog. While there is no concrete evidence to confirm this theory, impact from a cosmic body remains the most plausible explanation for the event
In 1934, Soviet scientists suggested that the cosmic body in question was more likely a comet rather than a meteorite. The reasoning for this was the comet’s composition of mostly ice which would have been vaporized during the impact and explained the lack of a crater or extraterrestrial materials. This would also explain the presence of noctilucent clouds over Europe after the explosion. Noctilucent clouds, also known as “night shining” clouds, are located in the upper atmosphere and mostly visible at twilight. They are composed of ice crystals which can be formed by the vaporization of a comet.
Despite the logic behind this reasoning, other theories have been proposed, some more realistic than others. Science fiction writer Aleksander Kasantsews suggested it to be a nuclear explosion from outer space. His theories were inspired by the 1945 bombings of Hiroshima and Nagasaki, and the similar geomagnetic disturbances caused by those events. In 1973, American physicists theorized that the explosion was a matter-antimatter reaction caused by a small black hole colliding with Earth. Recent studies from German astrophysicist Wolfgang Kundt, Jason Phipps Morgan of Cornell University, and Paola Vannucchi from the University of Florence suggest that the explosion may have come from within the Earth rather than from outside of it. They put the blame on eruptions of a mixture consisting of magma and gas. These theoretical eruptions are called “verneshots,” named after science fiction author Jules Verne. This theory also accounts for the glowing clouds as possible chemical residuals which would have resulted from the release of compressed gases. However, this explanation should have left traces of the eruption, such as shattered rocks or craters, none of which was found.
While these theories do offer some explanation of the event, none match as well as that of a cosmic body impacting Earth, especially given witness accounts of seeing a fireball in the sky prior to the explosion. However, even that theory is not without flaws, particularly the failure to explain the lengthy series of explosions heard by several witnesses and lack of conclusive geological evidence. The one thing scientist can agree on is the fortuitous timing and location of the event as it occurred in the swamps of Siberia. Assuming the cosmic body theory to be accurate, a four-hour delay in impact could have resulted in the impact site being the Russian capital of St. Petersburg.
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