asteroid explosion

On the morning of June 30 1908 something exploded over the remote Siberian taiga with a force estimated at 10-15 megatons — equivalent to 185 Hiroshima atomic bombs — flattening approximately 2000 square kilometres of forest and sending shockwaves that were recorded on seismographs around the world. No crater was ever found. No extraterrestrial material was recovered for decades. It took 19 years for the first scientific expedition to reach the site. The Tunguska event remains the largest impact event in recorded human history.