If the sun ONLY resets if someone else is in your (new) hex, doesn't that mean you can tell if an enemy is hiding in the hex you just entered, based on the sun resetting?
That would require that you leave the hex, the enemy enters the hex, their time passes, and then you reenter the hex, all in the same day.
Since you can only move on your turn, this would not be possible.
no, i mean, what if an illusomancer hides a ground army in a forest, and an enemy air unit flys over them on it's own turn. is it possible that the enemy air unit can't see them, but it CAN see the sun being in the 'wrong' place, thus suggesting that someone it doesn't know about has already observed that sun?
There's no reason why the sun would have to move. The Foolamancer couldn't have possibly acted since its own turn ended, so the whole hex, and the sun from its perspective, could have just "waited" until it was in a position appropriate for the scout. Nothing of importance happened between the Foolamancer ending turn and the scout's arrival, so there's no reason why it would be otherwise, except just for the sake of being contrary.
So if the Foolamancer hid there at its 11:00 and then ended turn, and the scout arrived at its 4:00, the sun wouldn't be in its 11:00 position. The Foolamancer (and thus the whole hex) would have already waited five hours by the time the scout arrived. If, after that, a fast-moving assault force rushed the hex in less time than it took the scout, THEN the sun might have to move back. Unless it would just appear to move forward for the new stack...I'm not sure which Erfworld finds preferable.
That's my take on it, anyway. Doing anything else would just be needlessly complicated. I figure if things CAN work out without any time-jumping, it'll probably try to, just for everyone's convenience.