A detainment moon was a moon that was used to house anti-Imperial individuals and other criminals.


The detainment moons were established in the crackdown of Rebel activity before the Battle of Yavin in 1 BBY. The relocation of detainees was carried out through the use of massive Imperial prison barges, essentially mobile prisons—complete with guards and wardens—that traveled throughout the galaxy. One detainment moon was Gradient Seven.