The Visitor From Space
In the decades that followed, most scientists have agreed on two most likely explanations for what had occurred at Tunguska. It is quite clear that an object from outer space entered the atmosphere over central Siberia. Because no crater was ever found on the ground, and no meteorite either, it is thought that the object disintegrated (exploded) before reaching the surface. The blast area and other effects point to that conclusion, too. The two options, then, are what the object itself might have been. Some argue that it was a small asteroid, others that it must have been a small comet (or a comet fragment). The glowing skies – suggesting high levels of water vapour in the atmosphere – are more likely to occur due to a comet, but some investigations of the resin of the impacted trees noted presence of material common in asteroids and rare in comets.
There are numerous other indications, too, which go in favour of one hypothesis and against the other. 110 years later, the matter still hasn’t been resolved. If it was an asteroid, it was probably about 36 m (120 ft) in size and 100,000 metric tons (220 million pounds) in weight. A comet – being less dense – would have to be slightly larger.