Luna

Luna is Terra’s only moon, a fortified satellite whose gun batteries and shipyards form part of the defence of the Throneworld. Its shipyards and a broken defensive ring continue to cover the inner Sol system.

The moon’s vaults were formerly administered by the Selenar gene-cults. The Emperor suppressed these cults in the First Pacification of Luna, which allowed the Legiones Astartes (the Space Marine Legions) to be produced in numbers. That event belongs to the period of the Emperor’s rule and of Constantin Valdor. The Sisters of Silence later held the Somnus Citadel on Luna, and the citadel remains associated with the Silent Sisterhood.

Luna has been contested on more than one occasion. Fighting reached it during the Solar War, when the approaches to Terra were disputed, and again during the return of Roboute Guilliman, when Abaddon exerted pressure on the same Sol approaches that Guilliman had reopened. Its position beside Terra, together with its shipyards and defensive works, accounts for its repeated role in the defence of the Throneworld.