On June 30th, 1908, an explosion flattened more than two thousands square kilometres of Siberian taigà. During the following 111 years, several theories were proposed to explain the observed features. Basically, there is a general agreement on the collision of the Earth with a cosmic body, but still today there are doubts on the exact dynamics of the phenomenon and the nature of the body (comet or asteroid?). Particularly, I will address the atmospheric fragmentation and the possibility of a ground impact.