He walks through the mechanics of the Tunguska event, describing how an airburst roughly five miles up created a fire plume that incinerated hundreds of square miles directly beneath the blast. Outside that scorched zone, trees were knocked flat in a radial pattern, splayed outward from the epicenter. The pressure pulse hit the ground and spread laterally with devastating force. This wasn't a ground impact. The object exploded in the atmosphere, and because there's nothing to contain the shock in open air, the radius of destruction was actually larger than it would have been on a body without atmosphere. The pattern on the ground tells the story: incineration at the center, then a wave of mechanical destruction radiating outward.