The Milky Way’s Local Arm is Metropolitan
Earth’s arm of the galaxy is muscular, astronomers announced June 3 at the 222nd American Astronomical Society meeting in Indianapolis. While the Local Arm first appeared to be a mere “spur” of the larger Sagittarius or Perseus arms between which it is sandwiched, new evidence shows it to be a significant limb on its own. Either way, our picture of the Milky Way is changing and may continue to do so as telescopes become increasingly precise and sophisticated.
Scientists’ conception of our galaxy is still evolving because determining the Milky Way’s shape is like mapping a building while stuck in your office. Astronomers cannot step outside and observe the overall structure, so they have to get creative. To upgrade the Local Arm to a metropolitan area, the Bar and Spiral Structure Legacy (BeSSeL) survey team monitored the motions of molecules.