The world's largest explosion – an explosion in Russia the size of 185 Hiroshima bombs that was felt as far away as Britain and the US – remains a mystery after experts debunked the "proof" that it was a meteorite. A large fireball was seen streaking across the Siberian sky on June 20, 1908, before an eruption six miles above the ground felled 80 million trees and left charred reindeer carcasses.
Italian scientists spent 21 years researching the so-called Tunguska event, claiming that the blue waters of Lake Cheko filled in a 'disappeared' impact crater – giving rise to the theory that the phenomenon was caused by a meteorite. But a new study by Russian geologists suggests that this idea is flawed, meaning that the enormous explosion – which lit up the night sky in Europe and even America – remains a mystery, according to reports in Moscow. In a review published in 2016 in the Annual Review of Earth and Planetary Sciences, Natalia Artemieva of the Planetary Science Institute in Tucson, Arizona, explains that the event followed a clear course.
Whatever caused the event likely entered the atmosphere at 9-19 miles per second and would have been extremely fragile, disintegrating about six miles above the Earth.
The possibility of an asteroid explosion was first proposed in 1927 by Leonid Kulik, 20 years after the event. Others have suggested that the space object may have been a comet, made of ice instead of rock, meaning it would have evaporated upon entering Earth's atmosphere.
However, some scientists warn that these findings do not definitively explain the bizarre explosion – with meteor showers being a frequent occurrence, these samples may be the remnants of a much smaller, unnoticed event. To some extent, the Tunguska event remains a mystery that scientists are continually working to solve – but whether from a comet or an asteroid, most agree that the explosion was caused by a large cosmic body colliding with Earth's atmosphere.