I have no idea what I’m talking about but I imagine you could try and measure the speed of light to determine a true fixed point, theoretically?

Direction is relative. Gravity on earth it’s easy since we all have the same down. But in space you just orient on whatever you can to describe your frame of reference.

The enemy gate is down?

You pick a point of reference. Most things use the plane of the solar system or the Milkway Galaxy and the general direction the earth’s north faces as “up”. And then angle of inclination/declination from there.

no idea but I know they have done some experiments with space gps. I sorta feel like everything should be in relation to the sun and its rotation and the planets rotations and such. like I would make z above and below the plane of rotation. not real sure though how to decide x and y but you likely want the common rotation to be clockwise in the graph.

If you’re standing on a spaceship bridge with artificial gravity, you take your spaceship as a reference. Down is to everyone’s feet, forward is to the front of the spaceship and left/right will be to the left and to the right.

Too much science here…

Short answer, you can’t. E.g. on the international space station, you could have 1 person “standing” on 1 wall, while another is “standing” on the other. They would both see the other as upside down. Both would be right.

Long answer, we agree on common frames of reference. We already do this on earth. It’s just that in space, we don’t have gravity, and everything is moving around a lot already.

E.g. in a ship under thrust, thruswards is up. We could also use the plane of the solar system, or the direction of the local planet as a reference. All of them are arbitrary however.

Amusingly, if you continue down that rabbit hole, you encounter relativity. It says there are no prime frames of reference, EVERYTHING is relative.

This will help you understand very very deeply

Also: Noether deserves her place next to Faraday and Salk

https://m.youtube.com/watch?v=04ERSb06dOg

Pulsars, baby!

it’s all relative to a mutually agreed reference point. Within our solar system you might relate an object’s position as “sunward” or “outward”, and motion tangent to the rotation of the planets as “spinward” or “trailward”. In galactic space, the same directions apply, but substitute “coreward” for “sunward”.

I always liked this picture. Suppose you’re in a space suit, orbiting around the Earth. Gravity keeps you continually free- falling ‘down’ towards the surface below you. But, in orbit, you also have a velocity that’s tangent to the Earth’s surface. So while you’re falling, because that velocity is just right, the surface is curving away from you at the same rate!

So you remain at the same distance from the surface, and the ‘pull’ of gravity remains the same … orbit!

Direction is all relative, my friend. There is no objective up or down or left or right or north or south or east or west. The best we ever have is landmarks and pointing.

On Earth, that’s pretty easy. We have some pretty stable landmarks: up is away from the gravity. North is toward the pole that’s closer to more people. East is toward the way the sun comes up.

We can also get some directions from figuring out one we already know and going the opposite way. Down is not-up. South is not-North. West is not-East.

Being able to see one another, to know which way we’re pointing, gives us more options. Left is that way, right is that way.

You’ve been given all that for free every day of your life (assuming you’re a human who has never spent any appreciable amount of time in space). You were probably taught about North and South and East and West in elementary school. You probably got left and right from your parents. Up and down is hard wired into your senses.

But in space, all of those landmarks are gone. You don’t have any gravity to define up and down, you don’t have any poles to define north and south, you don’t have a sun rising to define east and west. So as a species we’ll have to decide on new ones!

It’s useful to use the sun as our point of reference, since it’s pretty stable for our purposes. A lot of scientific discussion uses the ecliptic as a handy way to define a similar idea as the equator. The ecliptic is the plane that most orbiting bodies move along as they orbit the sun (think “eclipse”–planets and moons and stars will eclipse one another on this plane), and while it’s not exact it is close enough to be helpful. “Above the ecliptic,” then, is more or less analogous to “North,” with “below the ecliptic” being analogous to “South.” And actually, since Earth never changes its orientation to the ecliptic, “above the ecliptic” is also pretty close to Earth North and “below the ecliptic” is pretty close to Earth South. We also use the Earth’s March equinox as the zero point in this system; the “prime meridian,” you might say.

Since almost everything we do is Earth-based, this is usually good enough. All of our telescopes are in the Solar System, all of our spacecraft are in or near it, any navigation we’re going to do will be based on it. But if we’re talking to aliens who have never been here, how are we going to explain it to them? How could we direct a friendly extraterrestrial to our solar system in the first place?

Now things get tricky. There are some shortcuts; the Galaxy has an ecliptic, too (called the “galactic plane”). There are terms like “spinward” and “coreward” that we can use. There are also some steady landmarks that we can point to: specifically pulsars, pulsing black holes that blink in easy-to-measure patterns. Those are visible from pretty much anywhere in the observable universe, so anyone we’re talking to can probably see them. Defining our location by how far away we are from a few of those pulsars could work; kind of like saying, “yeah, I live halfway between Orlando and Cocoa Beach.” But as far as anyone outside the government knows, we’ve never tried to do that.

But in general, you just sort of figure it out based on your use case and the landmarks that are handy to you!