In the Ecumene, there are almost as many classification systems for various types of celestial body as there are cultures. The Basic Classification system is fairly widespread, though it badly neglects planets, and takes up the first part of this page- the latter is a similarly common but less neglectful classification system for gravitational groupings of stars.

Basic Classification

The Basic Classification System defines a "planet" as any object that is not some variety of fusor/former fusor nor a large body that formed from gravitational collapse rather than accretion.

Basic Sizes

Star Clusters and Nebulae

Within the Ecumene's unified range of exploration- which varies greatly, but for this specific instance is about ten kilolightyears in every direction (note that a journey using fast drives to this distance is about nine years, one way)- there are perhaps a billion stars, but considerably less well-surveyed stars. Even a star directly visited by an expedition might only have some planets catalogued, and then may miss more- especially if a planet is more than just a rockball. This means it is far easier to divine the dispositions of grouped stars than the dispositions of individual stars- most small anomalies are discovered on later expeditions rather than the first to visit. Within the unified range of exploration, there are thousands of star clusters and nebulae of all sorts- even in the range of feasible colonization, there are hundreds.

Clusters

Nebulae

There are, of course, many clusters and nebulae actually within or adjacent to the Ecumene. Sector 593, the Grand River, is a sector slowly climbing up and down the nearest Torn Starway, the Bloody Stream (named for its abundance of ancient red dwarfs). Some of the closest proper star clusters to the Ecumene include the Great Shore, a tiny slice of a Dispersing Spherical Cluster that contains Sector 595; and the Chloricentric Sphere, which contains Sector 592. More dispersed clusters are more common- but are considerably less spectacular. Three large nebulae are contained within the Ecumene, but the largest is the Variegated Patina- an extremely colorful large starforming region home to Sector 591. Smaller clouds and jets are quite common, but rarely contain more than a few very young stars- if anything- and are therefore mostly useful for scientific study.

Note that the star clusters that exist on the map of the Ecumene may not actually reflect physical star clusters- see the map of the Sol region, part of Sector 594, where very close-together groupings of stars exist... despite the fact that very few of those stars are actually near each other. This is due to axes which generally exist less in FTL- running theories suggest that black holes and other singularities produce a "normalizing" influence which causes most local FTL systems to treat three-dimensional space as two-dimensional, with an axis along the poles of the singularity being "flattened". It is unknown why this effect occurs... but it certainly makes interstellar navigation easier. Still- if you're flying a slowboat, remember to procure a three-dimensional map rather than a two-dimensional one. It could save your life.

The Ecumene