The Emperor's psychic beacon, of course.
this post was submitted on 23 Sep 2024
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Asklemmy
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The Astronomican.
The Emperor Protects.
Cosmic background radiation provides a stable frame of reference for setting up a coordinate system. If the explorers have a main HQ base, it can be set as the origin (0,0,0). The location of an object in space can be communicated using a tuple like (10km, 30ยฐ, 30ยฐ), representing the radius (distance to the object), polar angle (angle between the positive z-axis and the line connecting the origin to the point), and azimuthal angle (angle between the positive x-axis and the line connecting the origin to the point on the xy-plane).
Alternatively, if only a general region is needed, grid coordinates can be used with any useful unit of measurement for the distance between grid lines.
Yep. Fun fact, if you used the center of the Earth at Epoch 0, the reference point would shoot out of central Africa a few seconds later in the direction of Ophiuchus.
Source: Napkin math that was surprisingly hard, because of all the moving parts with their own coordinate systems that don't necessarily have nice conversion tables in common use.
Center of gravity of the galactic cluster/supercluster
Works very well until you're moving between superclusters, at which point the universe becomes homogeneous (as far as is known). At that point you probably just need to set an arbitrary origin for your system of coordinates.
If we're talking intergalactic navigation, I'd use QSO J0529-4351 as north.
It has the highest chance of being visible from wherever we want to go.
I was going to suggest the Great Attractor or the Shapley Supercluster, but I think your suggestion is better. It's more point-like and since it's farther away (well outside of the reachable universe) it results in a more uniform set of directions over long distances.
Of course, cultural influence will be big. If these explorers are Terragen then most likely the Milky Way's north/south direction will be pretty deeply ingrained in their coordinate systems. They might keep on using that, since it's not like manual astrolabe-style navigation will ever be relevant at that level of technology.
I don't think it really makes sense to have a north as such. The only potentially exception I can think of is more of a definition of 'up' rather than north and pertains to hemispheres of bodies.
Earth-bound cardinals are basically 2 dimensional vectors. Not really helpful in intergalactic space.
You would likely start from the center of your galaxy, then pick a culturally relevant star near the outskirts, in our case Sol, and call that, well, something (Solbound?) Then work your right angles from there. You could pick other cultural stars in the other directions too.
Most galaxies are pretty flat, so you'd probably have to reference a conveniently positioned other galaxy for your up and down.
We could assign it to any point within a recognizable region in the Cosmic Microwave Background, which would probably be the most universally-applicable reference available. One just needs to be able to filter out the noise from surrounding celestial bodies. The CMB does slowly change over time, but so too does the position of stars within galaxies and galaxies relative to one another.
Earth, obviously. Or rather, where we think we left it...
By the time intergalactic navigation is relevant we'll have likely dismantled Earth. The vast majority of it is just sitting there generating gravity, a huge waste of its potential.
Collapse imminent in minus 3 minutes. Please vacate floor -14839.
Might be a bit simple but why not the "North Star" (Polaris)? Navigation could work via analysis of stars positions relative to eachother/positions of constellations relative to the ship. You could justify it in-universe as being a nod to how early mariners used these same stars to navigate Earth's oceans.