Moons and Plotholes

This post contains spoilers for the final chapter of Oathmaker! Please read it if you haven't already!

As I said last night, I realized there was a rather difficult plothole in the 'stinger' scene of Oathmaker, when Sunset Shimmer comes tumbling rather abruptly out of the portal. The hole was that the journal that keeps the portal open would have been on the floor, indicating that the portal would have been open under its own power due to the 30 moon cycle. However, on further thinking, this would have been impossible.

To explain why, first I feel I should give my thoughts on the exact amount of time that a 'moon' is. While, from what I understand, the majority of the fandom operates under the assumption that 1 moon = 1 month (and I cannot blame them for it), I personally find the notion to be...boring. Why bother coming up with a fantasy unit of time, only to make it equal to an existing unit of time? Especially when the people who make the show, as I understand, have kept the unit vague?

This is why, in all of my stories, 1 moon = approximately 3.5 days. To be specific, 1 moon equals the average length of time the moon spends in a single phase (i.e. new moon, waxing crescent, first quarter, waxing gibbous, full moon, and so on). There are two moons each lunar week, one beginning at moonrise on Monday evening and the other at moonset Friday morning. Thus, there are eight moons in a lunar month, and 104 moons in a lunar year. Which, incidentally, fits well with the schedule of Apple family reunions in the show - one in the series premiere shortly before the Summer Sun Celebration; the next a little earlier in the following year.

30 moons, in this model, would be about 3.5 months - which still makes the prospect of being trapped in the human world for that long rather panicking. Additionally, the whole 'the portal closes when the moon reaches its peak on the third day' works pretty well with this. Because the entirety of Equestria Girls takes place on school days, we have a pretty simple timeline of events in this model:
1. The portal opens as the moon rises Monday evening (or perhaps around midnight when the moon peaks); Sunset goes through and eventually steals the Element of Magic
2. Twilight and Spike go through the portal several hours later on Tuesday morning, spending all of Tuesday and Wednesday in the human world
3. The Fall Formal is held Thursday night, with the portal closing again when the moon reaches its peak.

Makes sense, right?

So, moving back to Oathmaker, and why the portal could not have been open at the end of it. First off, assuming that the CHS school year is similar to American schools (meaning that it starts in early September), we're looking at a Fall Formal in, what, mid-September at the very earliest? Meaning the closest portal opening to Oathmaker and Synchrony, which take place shortly after the summer solstice, would be in late July - a few weeks away in their time.

But even if the date of the stories, and of the Fall Formal, were to be manipulated so that the time was right...the 30-moon cycle combined with 2 moons a week means that the portal can only ever be open on its own on the same days it was in Equestria Girls, which would be from Monday evening to Thursday evening under my (non-negotiable) model. As the final scene of Oathmaker, as well as Synchrony, takes place on a Saturday...

So, all of that made me realize that the portal could not possibly have been open under its own power when Sunset came tumbling out of it at the end of Oathmaker. The normal solution would be to just have it forced open by way of the journals, but...would Twilight, or Starlight, or even Spike really just leave a two-way interdimensional portal open when they all were about to go out of town for however many days? And risk some random human stumbling through it into an empty castle? That strikes me as incredibly out-of-character for the three, Twilight especially.

And even if someone had simply forgotten to close it...why was it open in the first place? It doesn't strike me as something Twilight would just...leave open just because, not when nobody needs or wants to use it, not when keeping it open essentially means she can't read any messages that Sunset leaves in the journal.

Do you see the problem I was left with? The portal couldn't be open of its own accord, and it wouldn't have been left open by those in charge of it. But I needed it to be open so that Sunset could fall through it, for reasons that will be apparent in the future. So, what's a girl to do?

Admit the mistake, and assign the reason to some unknown and unplanned for entity to be determined in some future. Was it some new villain? Starswirl the Bearded, adrift in time? Angel Bunny out for a wild bender with his human-world counterpart? Somepony else entirely? I haven't the faintest idea right now, but I sure do look forward to figuring it out. At I mean that sincerely - this is a mistake I absolutely intend on turning into an opportunity.

But for now, don't expect any answers to that question in Synchrony.