The Core Systems, also known as the Core Worlds and colloquially called The Bubble, are a sphere approximately 150 lightyears in radius around Sol that contains the bulk of human civilization. It is where the Federation, Empire, Alliance, and other powers compete for influence, resources, territory and control. The territory volume is about 13.8 million cubic lightyears, and encompasses over 20,000 inhabited systems with over 66,000 stations, starports and outposts.
Human settlements are rare outside the Core Systems. Dozens of isolated Asteroid Bases exist in deep space nebulae, but the Pleiades Nebula and distant Colonia Region have become major hubs of expansion in recent years. The Core Systems are economically linked to Colonia by the Colonia Connection Highway, a string of planetary outposts established in nebulae along the main travel route.