Earth: The solar system's third planet, dominant in economics and military might. The birthplace of humanity, Earth is ruled by a constitutional monarchy, its king advised and served by regional parliaments and ministries that look after the interests of the planet's most powerful corporations. Earth's military power far outweighs that of the Jovian Union, but is limited by the vast distances of the solar system. Its formal holdings consist of Earth, the Moon, and the asteroids Vesta, Hygeia and 433 Eros. The Cantons of Mars are officially independent, but closely allied with Earth.
Earth has fought a number of wars with the Jovian Union, which it seeks to control through spies and its powerful military.
The Asteroids: The field of debris located between the orbits of Mars and Jupiter, rich in minerals and water ice. The largest celestial body in the asteroid belt is the minor planet Ceres, a trading hub that's neutral in the conflict between Earth and the Jovian Union. Other large inhabited asteroids include Vesta, Pallas, Hygeia, Hermione and Cybele. Vesta and Hygeia pledge allegiance to Earth, while the others are neutral.
While the orbits of many asteroids are elliptical and defy easy mapping, the belt is divided into a number of families. The nearest family to the Sun is the Hungarias, whose asteroids are strongly influenced by Mars's gravity. They're claimed by the Cantons of Mars and loyal to Earth. Next come the Floras, also part of the Martian Cantons. The central belt is made up of the Nysians, the Eunomians (which include Ceres), the Koronians and the Themistians. Beyond the 2:1 Kirkwood Gap are the Cybeles and finally the Hildas.
The Jovian Union: An alliance of inhabited moons and asteroids in the outer solar system, the Jovian Union declared its independence from Earth in 2590 and has fought several wars and a number of skirmishes with it since then. Its capital is Ganymede, a moon of Jupiter. Other Union members are Io, the Protectorate of Europa, Ganymede, Callisto (all moons of Jupiter); 624 Hektor, 617 Patroclus, 911 Agamemnon, 1172 Aeneas (all Trojan asteroids of Jupiter); Enceladus, Tethys, Dione, Rhea, Titan, Iapetus, Phoebe (all moons of Saturn); Miranda, Ariel, Umbriel, Titania and Oberon (all moons of Uranus).