Shadow on the Core
According to some sources, the galaxy was 120,000 light years across, or 37,000 parsecs (a parsec is 3.258 light years), and approximately 13 billion years old. A black hole existed at the center of the galaxy. The galaxy was orbited by seven satellite galaxies: Companion Aurek (also known as the Rishi Maze), Firefist, and Companions Cresh through Grek. However, most of the Companions were described as having ancient, metal-poor stars and not much life. There was also a hyperspace disturbance beyond the edge of the galaxy that prevented hyperspace routes outside the disk. The galaxy had nearly two hundred globular clusters.
While there was a hyperspace disturbance outside of the galaxy, hyperspace made it possible within the galaxy to have an enormous, and diverse, civilization. There were approximately 400 billion stars, and around 180 billion of these had planets that could support life. Ten percent of those planets developed life, while sentient life developed in 1/1,000 of those (about 20 million). Factoring in output of heat and light for advanced civilizations to form, there were 7.1 billion truly habitable stars, and 3.2 billion habitable star systems, with only 69 million systems meeting the requirements for Imperial representation, and 1.75 million planets considered full member worlds. In total, the galaxy was populated by approximately 100 quadrillion different life forms.
The galaxy was divided into ten main regions. They are listed here in ascending order of distance from the core to the fringe. These regions were further divided into various sectors, systems, planets and possibly moons.