On Earth, the cardinal directions are straightforward. The arrow on a compass points to the nearest magnetic pole. You can then use it to travel anywhere on Earth.
In space, the idea of anything being “central” enough to be used as a “North” (since the universe has no center) or being fixated enough to not somehow pose issues is more convoluted.
If you were a pioneer of space exploration, what would your “North” be?
The “prime meridian” is the line through the black holes at the centers of the Milky Way and Andromeda, and the “equator” is the galactic plane.
Up. North on a map is always up.
You’re in a random spot somewhere in the universe. Where’s “up”?
👆🏻
Over there.
Opposite from the enemy’s gate.
Jump. The direction you fall is down. Up is the other way.
Within the Milky Way a polar (cylindrical) coordinate system makes more sense than Cartesian - there’s an axis of rotation to define the center and ‘up/down’ directions. Zero degrees is arbitrary but a line from the galactic center to Sol, projected onto the galactic plane, would be an obvious choice as a sort of galactic prime meridian. ‘North’ and ‘south’ don’t really map to a roughly disc shaped galaxy - you’d use distance from center, angle, and ‘elevation’.
On an intergalactic scale, the center of our own galaxy is probably still the obvious choice for a center point. We could use the same axis and meridian - I don’t think the rotation of our galaxy matters on any human timescale, and on the time scales where it does matter, everything is moving relative to each other so coordinates already aren’t ‘fixed’. I’d use a spherical coordinate system instead of cylindrical for intergalactic coordinates, since things are not roughly in a plane anymore.
If you want a fixed coordinate you’d have to include a time dimension, and as the zero point for time I propose the Unix epoch. Not because it makes any sense but because it’s extremely funny to imagine computer systems in the year 10000 still relying on that legacy decision. Though special relativity makes ‘point in time’ rather complex as well - I don’t know enough to know what you’d actually need to make that work.
Of course we already have such coordinate systems for astronomy if you want to know the ‘real’ answer, one of them is pretty close to what I just came up with: https://en.wikipedia.org/wiki/Astronomical_coordinate_systems
Your polar coordinate system still needs an “angle 0” which is somewhat analogous to “North”.
Somewhat but not exactly. You can only go north or south until you hit the poles, but you can travel forever at angle zero starting from the center point. I guess you could call towards the center point “North” and away from it “south”, so the galactic center is the North Pole but there is no equivalent South Pole. But angle zero is more analogous to the prime meridian - it’s a line that goes north-south but there are an infinite number of such lines, and we could have called any of them zero.
SagA*
It’s as good a place as any other.
I think you would pick a north depending on your place of origin. Probably from either their own planet or, more likely, their own galaxy.
But when you get to another galaxy you’d probably have to pick again. Galaxies aren’t all oriented the same way but they do roughly spin at the same speed. So, just like earth, from a certain point of view everything spins around the north south axle. But that does not have to line up to your home galaxy. And even if they did, it might spin the other way around. Much like venus spins in the opposite direction of the rest of the planets in our solar system.
What I’m trying to say is that using a universal North is completely impractical for intergalactic space travel. So you’d probably use a local system. And where that’s not possible, you’d probably use your point of origin for orientation.
I would just spin a quantum gyro, and let it decide…
The location of our solar system. Everything would be in relation to where our solar system is in relation to where you are.
Pointing at the north pole of Earth. You didn’t stipulate any other spacefaring species, so it’s not like there’d be competing standards.
M87
We could keep using Polaris or find some really far galaxy or star as the north.
Removed by mod
