2. Tunguska: The Russian Roswell

Just prior to the Russian Revolution a mysterious 40 megaton explosion lays to waste nearly 200 square kilometers of Earth in the desolate northlands of Siberia. The Official Story alleges the impact of an asteroid, but no known scientific explanation can account for the metal fragments found at the site, the lack of an impact crater or the high level of radiation present. Was it an asteroid? Or could it have been the explosion of an extra terrestrial craft? Scientifically speaking each conclusion has equal merit.