Astrography of the Known Sphere

The Known Sphere is the explored portion of the galaxy, an area of space encompassing over five thousand charted star systems, of which approximately one thousand are inhabited. However, with the attendant destruction and chaos caused by the Second Unification War and all the grey activity in Wild Space, reliable numbers are hard to come by. The "Sphere" has more of a discus shape, roughly centered on Terra and radiating outward in all directions.

The Known Sphere is broadly divided into two areas: the Core Systems, and Wild Space. There's no bright line dividing the two: freedom and disorder tend to increase as one approaches the frontier, and exactly when a traveller crosses over into Wild Space is somewhat subjective.
 
 

Composition of the Known Sphere

The Core

As this area is also nicknamed "the Old States," unsurprisingly, the oldest, most developed and most technologically advanced star systems are found here. The Core is home to the galaxy's major centers of politics, education, industry, commerce, research, and military might. Unfortunately, most of the ravages of the Second Unification War also took place here. Hundreds of systems were caught in the conventional and nuclear crossfire, and scores of worlds were reduced to ash and cinder. Nevertheless, the Old States are still home to the great majority of humanity, and, with the end of general hostilities between the superpowers, an unprecedented wave of reconstruction has started.

The worlds considered in "the Core" have changed over time, with the Core growing as regions became increasingly settled or shrinking following the destruction of the Second War. This region can be subdivided geographically (Near Core, Far Core), politically (Red Core, Blue Core, and Gold Core for the respectively spheres of influence of the Terran Military Order, the Republic of Akasha, and the Federation of Corvia), or by region (e.g., the Rixian Marches).
 

Wild Space

Wild Space is usually loosely defined as the explored area of the galaxy beyond the day-to-day reach of the superpowers. This works out to be the territory from the rim of the Old States out to and including the frontier. The settlements in Wild Space tend to be newer and smaller, with most established in the 22^nd century. Conditions, infrastructure, and available technology and amenities vary greatly from world to world, though, in general, circumstances tend to be far more spartan than in the Core.

Certain regions of Wild Space, such as the Tangent, are still relatively safe and civilized. However, for the most part, this region is filled with bandits, outlaws, con artists, warlords, rogue elements of defeated armies, and other dangerous inhabitants. Settlers, prospectors, and other fortuneseekers are commonplace, as well as millions of displaced refugees. Also, because the central governments' authority is weak to nonexistent here, Wild Space is also filled with individuals seeking freedom, adventure, and excitement. Meanwhile, the fate of many turns on the actions of a few, exceptional individuals…the Space Cowboys.
 
 

Anatomy of the Known Sphere

Corridors

Space is big. Really, really big. And really, really empty. Despite the wonders of FTL, given the distances involved, point-to-point interstellar travel is usually not feasible. Thus, for most journeys, ships periodically need to emerge from H-Space to take on more catalytum, fuel, and other supplies before reaching their final destination.

Space lanes are formed by this limitation, along which most travel and commerce are conducted, and are called Corridors (e.g., the Gwaden Corridor, the Achaemen Corridor).

The particular path that a corridor takes depends both upon the placement of local star systems and upon what resources, if any, are present in said systems. These factors are also critical in the traffic and development of a particular corridor, with convenient and resource-rich corridors becoming major hives of activity, and inconvenient and resource-poor corridors being gradually abandoned over time.
 

Hubs

Formed by the intersection of two or more corridors, Hubs are vital entrepôts and have a sizable permanent population (and a far larger transient population), and a massive infrastructure to support its traffic, including advanced and extensive interface facilities, considerable ship building and repair yards, hospitals, financial and communications amenities, a dizzying array of entertainment options, and anything else a traveller might need or desire.

Hubs are of vital strategic importance because they are natural chokepoints where the controlling party can regulate the flow of interstellar traffic in multiple directions. As such, defense is a paramount concern and a hub is typically home to at least a squadron of capital ships and attached support vessels, and substantial ground forces, a division, if not a corps or even a field army.

Additionally, controlling multi-star system countries typically located their national capital (for regional powers) or a provincial capital (for great powers) at the hub to strengthen centralized control.
 

Excerpted from: Dr. Becky Banzai, The Known Sphere: A Traveller's Guide, Kyodai Ryu Publishing, 2150