The Tunguska event was a natural explosion that occurred at 60°55′N 101°57′E, near the Podkamennaya (Stony) Tunguska River in what is now Evenkia, Siberia, at 7:17 AM on June 30, 1908.
The explosion was caused most probably by the airburst of a meteorite 6 to 10 kilometers above the Earth's surface. The energy of the blast was later estimated to be between 10 and 15 megaton TNT. It felled an estimated 60 million trees over 2,150 square kilometers.
In recent history, the Tunguska event stands out as one of the rare large-scale demonstrations that a full doomsday event is a real possibility for the human race.
See also: The Tunguska event in fiction.
The Tunguska event is just one of the many tidbits for your consideration in The Know-It-All
, A.J. Jacobs's amusing (if not especially well-written) account of his attempt to read the entire Encyclopædia Britannica