Core worlds or core planets often exist in works of science fiction, especially space operas. They are usually at the center of the galaxy or of colonized space, occasionally both. Core worlds are densely populated with long histories, highly advanced technology, and/or highly developed culture. The capital planets of galactic empires and galactic republics are often core worlds. In many cases, these worlds are considered the economic, cultural and political centers of known space.
A world that is the birthplace of the given race is often known as its homeworld (sometimes abbreviated in fandom as HW) or home planet. For example, Earth is the homeworld of the human race, and the Solar System is its home planetary system (home system) plus the Sun. Note that a homeworld is not necessarily a core world - especially once its natural resources are depleted, and much population emigrates to search for life in space colonies (this is for example the fate of Earth in the fictional universes of Legend of the Galactic Heroes and The Foundation Series).
Some universes including core worlds:
- Homeworld the game has a core-world: Hiigara, the homeworld and cradle of the Hiigarans.
- Star Wars, the Core Worlds are the known worlds, or planetary systems, that are near the core of the Star Wars galaxy.
- Firefly may take place in a single solar system (see Firefly) with an extremely high number of habitable planets and moons; there exists a distinct core worlds sector, including planets such as Ariel and Persephone.
- The Galactic Empire from the Foundation Series has a distinctive core, including the city planet Trantor, after which Star Wars' Coruscant was modelled. Foundation's Edge also mentions Imperial "Inner Provinces."
- The Galactic Imperium of the Padishah Emperors in Frank Herbert's Dune is not stated to have any particular structure, but the planet Kaitain is noted as the seat of power.
- The Solarian League in David Weber's Honorverse also has core worlds consisting of Earth and its oldest colonies, with Earth being the capital.
- In the Babylon 5 universe, many of the major races have specified core worlds. The Homeworld of the Minbari, Minbar, acts as the capital for the Minbari Federation. The Centauri Homeworld acts as the seat of power for the Centauri Emperor and capital of the Centauri Republic.
- In the Star Trek universe, the core worlds of the United Federation of Planets consist mainly of its founding members: Earth, Vulcan, Andoria, Alpha Centauri, and Tellar.
- In Warhammer 40,000, there are several core worlds spread out through the galaxy around which less important planets seem to cluster in order to survive the war against Chaos and various aliens. The most well known examples are; Earth (Mars), Cadia, Armageddon, Macragge, Ryza, Stygies VII, Necromunda, Ophelia VII, Kar Duniash, Hydraphur and Bakka. Several "core worlds" have also been lost in recent times (Gryphonne IV), but only due to massive invasions by Tyranids or Chaos.
- The Inner Colonies, including the Earth and Reach, in the Halo series.
- Craig Carey, Chris Doyle, Jason Fry, Paul Sudlow, John Terra, and Daniel Wallace, Coruscant and the Core Worlds (Wizards of the Coast, 2003).