I know this can be hard to picture in your head, but the beauty of it is that once you do, this map sings. You can instantly see what’s what: the motion of the gas, where it’s more dense than other locations, how it’s distributed. It also shows our location in the galaxy! All those changing velocities depend on the Sun’s velocity, the velocity of the gas, but also the direction of the Sun’s motion and its position in the Milky Way’s disk. That’s a stunning amount of information.
This is fascinating.