Gamma-ray bursts reveal Milky Way's outer arms extend 10% farther than thought

From the violent deaths of stars in distant galaxies, light has returned to us a more honest portrait of our own. Three gamma-ray bursts, among the most energetic events in the universe, cast X-ray echoes through the Milky Way's dusty spiral arms — and in the geometry of those expanding rings, astronomers found that our galaxy's outer reaches extend farther than our models had dared to place them. It is a reminder that the home we thought we knew still holds surprises, and that sometimes it takes a light from elsewhere to illuminate where we truly are.