The article linked in Mark's column reminds me of another Russian, Immanuel Velikovsky, who posited that the catastrophes described in the Bible were caused by the planet Venus wandering around the Solar System like a mis-shot billiard ball. At least the current theory doesn't break any basic physics, which Velikovsky's theory very much did.
Science! I found this rather interesting article which describes a new claim for the cause of the 1908 Tunguska explosion. The magnetic field of Jupiter is capable of inducing electrolysis in the icy moons that orbit it, creating pockets of pure oxygen and hydrogen gas. An impact on one of those moons would cause an explosion, sending chunks of ice into space. The object that hit Siberia could have been one of those chunks, charged up with pure oxygen and hydrogen that would blow up in a huge fireball triggered by the heat of entering Earth's atmosphere. I'm not sure I quite buy this but it's certainly an imaginative theory.