Over 100 years after the most powerful explosion in documented history, researchers are still trying to figure out exactly what happened *http://www.bbc.com/earth/story/20160706-in-siberia-in-1908-a-huge-explosion-came-out-of-nowhere <http://www.bbc.com/earth/story/20160706-in-siberia-in-1908-a-huge-explosion-came-out-of-nowhere>*