The Milky Way may seem like a tranquil place, but it has a turbulent past. Our home Galaxy has consumed at least half a dozen other galaxies during its roughly 13-billion-year history. Now, astronomers have begun to identify the remains of its meals smeared across the galactic halo, a huge spherical volume taking in the Milky Way’s spiral and much space beyond.
Source: The Milky Way Is a Messy Eater. This Map Shows the Crumbs It Has Left Behind | Portside