It Fell From the Sky

The Tunguska Event
Though it flattened all the trees in every direction for 30 miles, the airburst that took place over Siberia's Tunguska River left no crater behind. Scientists theorize that the blast, caused probably by a meteor or comet fragment that exploded a few miles over the surface of the Earth, was 1000 times as powerful as the bomb that fell on Hiroshima, Japan.

• Women of Space