One of the greatest scientific mysteries in history occurred as a 30 Megaton air burst occurred over Tunguska, Siberia flattening almost 1000 square miles. The shock wave knocked people off their feet and shattered windows 500 miles away. The blast wave was detected in London and Washington DC...........It has been theorized that it was either a small comet of a large meteor up to 600 feet across, they have now found fragments of the meteor believed to have caused the explosion