[Solar System] When do rocks fall in the Solar System?

An interesting question, this.

My own answer would be to challenge the old "rocks fall" question as an invalid rules question. This is because the question presupposes a break-up of the social contract of play.

By the above I mean that the question sort of presumes that the Story Guide is just being a dick, in which case there is no reason to take his narration seriously (or play the game at all for that matter). However, if he's not, then the problem disappears, because he had a reason for what he was doing. Was he scene framing? If he was, then the event of rocks falling was just set-up for the real situation, which will follow. Was it a consequence for a choice? If it was, then the player should have been aware of it (or of something, at least) in advance, so he could make the choice well. Was it a conflict outcome? If it was, the conflict can be extended, which affords major narrative protection to characters.

The exact conditions of the situation would determine how the Story Guide's narration would have to be taken. If it was just free narration with dramatic coordination in mind, for instance, then it would be entirely appropriate for a player to declare that his character is going to do something about the rocks falling. This would then go into the conflict resolution procedures. The most important of these is the evaluation of stakes, where the system is going to break down if the Story Guide is being a dick: you see, while the player gets to choose what his character wants and tries to do, the conflict stakes, what is actually being resolved, are chosen by the Story Guide. So if the Story Guide was just relinquishing his job in the game to stop playing in a dramatic manner, then he might have rocks fall and prevent all reasonable conflicts.

If the SG was playing in good faith, though, he'd by necessity have to allow a conflict with stakes like "whether I notice it and get out of the way"; he might opt for lethal stakes, but even that is only possible if those are allowed by the propriety considerations of the group.. After this it's largely out of his hands, because the rules would determine the opposition (nothing, unless the rock fall was being caused by a dramatic actor: a character). After the conflict is accepted, the player just needs to win it to protect his character from the rockfall. Even if he loses, he can extend the conflict, which protects his character most completely from immediate death.

Anyway, I have to get going. If your real question is what happens when the Story Guide is a dick, then the only answer is that the game ends; his job is too important for the game to handle a terrorist on that particular seat. If the real question is how the system handles sudden natural disasters, then it's normal procedure: determine goals, determine stakes, resolve conflict, narrate consequences. I'd probably set a rockfall at Harm 4 myself if it was a severe one, at least in a heroic fantasy genre.