What was the Siberian fireball?

One of the more intriguing mysteries of history is investigated in this episode of In Search Of….  Leonard Nimoy narrates!

(It’s always strange to me that there hasn’t been hundreds of movies made about the Tunguska event.  I know that the current popular theory is that it was a comet or, at the very least, a really big asteroid.  Personally, I like the theory that it was Nikolai Tesla testing out a death ray.)