Therefore it is possible to believe that explosion of Tunguska was the explosion of asteroid .
Therefore , it is possible to believe that the Tunguska explosion was caused by an asteroid . Therefore it is possible to believe that the explosion of Tunguska was the explosion of an asteroid . Therefore it is possible to believe that the explosion of Tunguska was caused by the explosion of an asteroid . Therefore it is possible to believe that the explosion of Tunguska was the explosion of an asteroid .