If I had a nickle...
I disagree a little that physical PODs belong in ASB. The accidental trip that begins
Look to the West is probably just as likely as something slowing/accelerating the Tunguska object just a little bit. We just don't know is the problem with celestial events and when one is dealing with incredible distances and incomprehensible speeds, small changes can probably make massive differences.
We say it is ASB because the difference is put as "Tunguska hits London!!!!" but if it written as,
"Somewhere between Mars and Jupiter, a rock, roughly five miles across, is speeding towards the inner regions of the Solar System. It is on a collision course with the third planet, Earth. Against all odds, it passed relatively unscathed through the gauntlet that is the Asteroid Belt, save for a few scratches. Yet, just as its fate looks clear, its passage safe and determined, the rock smashes into, and through, a clump of dirt, half a mile wide, slowing the rock's velocity by only a few meters per second.
"In the scale of the universe, this change is of no minor consequence. It would still hit the third planet rotating that particular star. It would only hit a few hundred kilometers 'west' of its original impact site, before that clump of dirt got in that rocks path. Instead of that remote forest in the middle of Asia, away from human settlements, it would strike one the most important and largest human settlements of the era, the city of St. Petersburg."
When put like that, it seems more reasonable, at least to me, to say that such a change is plausible and not ASB.
However, the Tunguska event question is fairly covered and asked and there are more unique and creative changes that could be done.
