There are nine nation-planets described in the novel Carve the Mark surrounding one sun. The planets are governed by the Assembly, which regulates trade, weapons, treaties, and travel, and enforces laws in unregulated space. Each nation-planet is independent besides, each with three oracles - one rising, one sitting, and one falling. When a fate is ascribed, each oracle sees the fate in unison.
There are other, smaller, fringe planets, surrounded by the Currentstream. On the other side of the Currentstream is the Brim.