On a clear night, away from city lights, you might see a beautiful structure arched across the sky: our home galaxy, the Milky Way. Since ancient times, humans have marveled at the dark dust clouds silhouetted against the milky background. Just four centuries ago Galileo pointed his telescope at the heavens and found that the milk was the blended light of countless stars.
The architecture of the Milky Way has just been revised again. Using an entirely new type of telescope, we and our collaborators have discovered colossal structures that tower over the galactic center and extend tens of thousands of light-years into space. These luminous lobes have gone unnoticed for so long because they glow brightest in gamma rays, which cannot pass through our atmosphere.