Mystery space blast ‘solved’. The famous June 1908 monster blast — estimated at 10-15 megatons — in Tunguska, Siberia seems to have been an asteroid. Solving such a mystery is a letdown in a way; there were many more exotic and bizarre explanations floating around out there — like a collision with a wandering chunk of antimatter or the detonation of a disabled extraterrestrial spacecraft. The event had a starring role in an X-Files episode one or two seasons ago, if I recall… BBC