Sol System

The Sol System is the Terran star system of Segmentum Solar, seat of the Imperium and home to Terra and Mars. Holy Terra, Luna, the Ring of Mars, Saturn's Inquisitorial belt, and Titan of the Grey Knights all share this one gravity well, gated by the ancient Elysian and Khthonic warp routes.

The Emperor's unification, the First Pacification of Luna, the Martian Compact, the Solar War, and the Siege of Terra all happened here. Later millennia added Lion's Gate, Guilliman's return, and a defence grid so dense that even a primarch's fleet asks permission. Mercury's mines, Jupiter's forges, and Pluto's outer watch are not flavour text — they are why Terra still has a sky.

The Sol System still matters because every Imperial map is measured from this origin. Unofficial fan summaries keep the subsector-solar parent, leave Terra at the chart origin, and do not flatten the system into a single Throneworld pin.