Milky Way Could Be Bigger and Wider Than Previously Thought

New measurements from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton suggest the Milky Way’s spiral arms extend about 10% farther and are roughly 3,500 light-years wider than previously estimated, based on X-ray echoes from gamma-ray bursts reflecting off dust in three arms (Perseus, Outer, and Outer Scutum–Centaurus). This direct geometric approach could revise our understanding of the galaxy’s mass distribution, rotation, and overall structure, though gamma-ray bursts are rare and the data come from only a handful of usable events.