The Supermassive Black Hole Around Which Moving Was Done

On further reflection, occasioned by a comment, I have realized what the directions are, in this galaxy (or any other spinning one). I have never been gladder that I live in a town that's 1/8 Navajo. Because the solution is so simple...provided you come of a culture, as they do, where "zenith" and "nadir" are listed among the cardinal directions.

Here's how it works. The objective traits of a galaxy are "spinward, leeward, rimward, coreward", because the direction it's spinning toward, the direction it's spinning away from, and closer to/further from its core, are real things. So:

1. Assume the core is the Earth. Put your feet toward it.
2. Face spinward.
3. Galactic north is on your left.

The puzzlement arose because I was treating the core as a thing like north (remember I said "with the core on your left"), when the core defines up and down. Once you have East/West and Zenith/Nadir, North/South follows automatically. There's no need to try and arbitrarily decide whether you want to define "north" as having the galaxy rotate clockwise or counterclockwise; it's decided based on East and Zenith, which are both objective.

There's really no excuse for not having realized it sooner, I'd actually considered changing references to "orbital distance" in my aliens' dialogue to "altitude" (moving nearer or closer to the central body, namely a star), but I, being a Westerner, am only used to there being four cardinal directions.

Sometimes, Native Americans really do have insights Westerners lack, it ain't all hippie stereotype—in this case, because Navajo orienteering is based on "what is the sun doing" rather than "what does the map say".