The 1908 devastation of hundreds of square miles of dense forest near the remote Tunguska River valley in Siberia. Faint aftershocks were felt around the world, and people 80 kilometers (50 miles) and more away saw a gigantic “pillar of fire” from the explosion that caused the devastation. Its cause remains a mystery. It occurred in an inaccessible region at a time when Russia was in a state of prerevolutionary chaos. The government could not mount a scientific expedition to the site until nearly two decades later. Then Leonard Kulik, a Soviet mineralogist, took a crew to the valley and searched for the evidence that would support his theory that a large meteorite had crashed into Earth. He was unable to find sufficient evidence, although he did find a small amount of meteoritic dust and a few small craters. Most puzzling was that he found no large crater, as a meteorite that caused such massive damage would certainly have created. Also, the destruction was less at the center of the explosion than in the surrounding area. The trees seemed to be burned from above and lay like matchsticks, facing out¬ ward from the epicenter of the explosion. This does not fit the pattern of a large extraterrestrial stone striking Earth.
Since that time, many theories have been suggested, including a black hole striking Earth and a nuclear explosion from an extraterrestrial spaceship. Most plausible is that it was an extraterrestrial body most likely a comet or an asteroid that exploded in the air before it could strike Earth. Most of these space bodies do burn up when they enter Earth’s atmosphere, with only a few maintaining enough mass to strike and make a crater. (Meteor Crater in Arizona is one of the rare craters caused by a large body striking Earth; most craters are quite small.)