Thought I needed to mention the Tunguska event in 1908. It turned out it was already mentioned in the Nature article. Anyway, here is the wiki link to that eve

Thought I needed to mention the Tunguska event in 1908. It turned out it was already mentioned in the Nature article. Anyway, here is the wiki link to that event http://en.wikipedia.org/wiki/Tunguska_event http://en.wikipedia.org/wiki/Tunguska_event When I was a kid who was fascinated by UFO stuffs, that one was always speculated to be an explosion of an Alien spaceship.