galactic north

This isn’t entirely unreasonable to determine, since the galaxy is a big disk and you could map that as a 2D plane. For the most part, ships are traveling across the plane between planets, in the same way that a ship flying from Earth to the Moon or Earth to Mars would be flying through a plane perpendicular to the two bodies. Not a lot to visit above or below the plane, and the shortest distance would be between two points, so…