In Frank Herbert’s fantasy-influenced novel Dune, House Atreides’ homeworld is called Caladan.
Caladan is an oceanic planet and the ancestral fief of House Atreides. Duke Leto Atreides rules there before the imperial order transfers his family to Arrakis, the desert planet that produces the valuable spice melange. The move is presented as an honor but is also part of a political scheme against the Atreides.
The contrast between Caladan and Arrakis is central to the novel’s atmosphere. Caladan is associated with water, rain, forests, and the Atreides family’s established identity, while Arrakis is defined by deserts, scarcity, sandworms, and the Fremen. Paul Atreides must adapt from one environment to the other as his political and prophetic importance grows.
Arrakis is therefore not the answer, even though it becomes the family’s assigned world and the novel’s principal setting. Giedi Prime is associated with House Harkonnen, while Salusa Secundus is the Imperial House Corrino’s former homeworld and prison planet.