Stars could travel from deep within the interior of a galaxy to its outer edges, and might even get passed around in a "spiral arm relay," Roskar told SPACE.com. Our sun currently has an orbit near the outer edge of the galaxy.

New simulation runs confirmed earlier work that showed how star orbits can remain circular despite expanding or shrinking. That counters assumptions that the gravitational tug-of-war would push and pull orbits into wilder elliptical shapes.

One of the commenters on the site notes that we won't really know the structure until we get a probe out of the galaxy. Wormholes and hyperspace drive were suggested. Works for me.