So, lets start from the beginning.
The Night of Sorrows is an event that was mentioned since the WoK, and was only mentioned 3 times in all of the 4 books.
in my opinion the night of sorrows talks about the event in which the sun in Shadesmar will set, as we all know right now it is Just above the horizon. but up to here I haven't said anything new, this theory was already proposed, but I'm pretty sure i have a proof that this happens by the end of book 5, and here comes the reason I put this in the cosmere and not stormlight dissuasion.
In misborn secret history, which we know is about 300 and something years before the events of stormlight, we get the first description (that I can remember) of the sun in the cognitive realm, and it is described as in the middle of the sky, than in the end of the bands of morning we get our next description from Scadrial, and it is described as just below the horizon.
If we assume this is the same sun all across Shadesmar this means that somewhere between the end of RoW, in which the sun is above the horizon and the end of The BoM the sun sets. Since we know mistborn era 2 happens between book 5 and book 6 i assume something happens in book 5 that makes it set.
It might all be a coincident, but I think its much more plausible that something wired is happening because of the timeing and the general importance of the sun (for example jasnah's icon).
what do you think about the theory? do you have an idea what the sun setting might cause?
