Comment by narag
5 hours ago
I wonder if anyone has made a physical galactic orrery.
Maybe it's harder than it seems. Does a definite galactic plane even exist? The ecliptic is defined by Earth's orbit, not a mean of all the planets. IIRC Sun's rotation plane is not aligned, not should it matter.
If there's a way to measure galactic plane, independently of Sun's orbit around the galaxy center (that also seems difficult to determine) it would involve measuring positions and trajectories of many very distant objects.
I believe such data exists--examine the movement of all galactic objects you can. That will give you a center of mass, the galactic plane is the plane such as to minimize the total distance from objects to the plane.
Yes, an example is "Local stellar kinematics from Hipparcos data" [0]. Afaict: stars have color (red or blue shift) which represents relative motion; Hipparcos is a large large dataset from an eponymous satellite; fancy math determines relative motion based on position and inferred distance.
0. https://arxiv.org/abs/astro-ph/9710077