Comment by pieix

There's a lot more out there that we just haven't seen, probably in all directions. Hard to spot stuff that far out from the sun.

The analog for cardinal directions is the direction of Vernal Equinox — the line in the ecliptic plane (Earth's orbit) formed from the Earth to the Sun at the March equinox. (there's an indicator for this in the corner of the app). This is usually treated as +x, with rotations within the ecliptic given relative to this axis. Then there's ecliptic north and ecliptic south that define +z and -z as the normal vector to the ecliptic plane.