In the early morning of July 1st 1908 in Siberia, there was a great explosion. Eyewitnesses close to the explosion reported the loud thundering sound moving east to north. The sounds were accompanied by a shock-wave that knocked people to the ground and broke windows hundreds of miles away. The explosion knocked over an estimated 80 million trees over 830 square miles. Estimates of the energy of the blast to be about 1000 times as powerful as the bomb dropped on Hiroshima. It is estimated that the earthquake from the blast would have measured 5.0 on the Richter scale, which was not yet developed at the time. Since there was no discernible impact zone, meteor impact was ruled out, theories for the cause range from black holes, anti-matter, to a UFO crash. Today the more popular theory is whether it was a comet or meteor, it exploded 8 or 9 km over the earth’s surface, from immense built up pressure from traveling over 21,000mph into our atmosphere. Later in 1966 Guiness book of world records calculated that if it were to hit earth 4 hours and 47 min later it would have completly destroyed St. Petersburg, Russia! They say the earth gets these mid-sized hits once every 300 years or so. 100 down 200 more to go!