In the early morning of June 30, 1908, natives of remote Siberia witnessed a strange flashing in the sky. Minutes later a massive explosion ripped across the tundra, flattening trees and killing wildlife across approximately 2,000 square kilometers of wilderness. The explosion was the equivalent of 3 to 5 megatons of TNT – about 300 times stronger than the atomic bomb dropped on Hiroshima. The exact cause of the so-called Tunguska event has long been a matter of debate, though most scientists now think it was caused by an above-ground detonation of a part of either an asteroid or a comet. However, conspiracy theories abound as with any major event such as this. No human casualties were reported.