The Milky Way as a subway map...

[Mr. Laser Beam]

Not sure I understand it. Basically the shape of this map is of the barred spiral galaxy that makes up the Milky Way galaxy, with corresponding spiral arms. But I don't get why omicron 2 centauri is where it is, or how distances are plotted.

That's the thing about a schematic-style map. It's less about representing true geography, and more about relative geography, which makes it more usable for transit riders.

Except in New York City. Anybody remember Massimo Vignelli's map from the 70's? Pretty, but very hard to use as an actual functional map.