Planet

The planet Alderaan A world, often referred to as a planet, was a type of celestial object that orbited a single star or multiple stars. A system of worlds revolving around a star could potentially arise when wandering clouds of gas and dust located beyond the star coalesced. According to numerous scientists, a world needed to possess sufficient size for its gravity to have 'cleared its orbital path' by drawing in all the smaller objects within its vicinity, excluding its own satellites, known as moons. In addition, a world's gravity needed to provide it with a stable shape, resulting in a consistent, rounded ellipsoid form, although some worlds did not exhibit a regular shape. As time passed, the definition of a world became more intricate, as scientists sought to exclude objects such as near-stars, wandering rogue worlds, dwarf planets, 'micro' worlds, companion stars in binary star systems, objects within asteroid belts and debris fields, and various other entities.

There were two primary categories of worlds: gas giants and rocky worlds. Gas giants mainly consisted of gaseous layers and lacked a solid surface. Their atmospheres typically comprised mostly hydrogen and helium, although some contained oxygen-rich layers capable of sustaining life. Due to their substantial size, gas giants possessed strong gravitational fields. The lower regions of a gas giant's atmosphere featured pressures capable of crushing any standard starship, and the core of the majority of gas giants consisted of a compact, dense metallic substance. Rocky worlds were considerably smaller and exhibited a wide range of characteristics. A number of rocky worlds lacked a rocky surface; some of these worlds were covered in water, which could exist as freely flowing oceans or enduring ice formations. On numerous other rocky worlds, the rock had been broken down over time, creating a fertile soil that supported a planet-spanning arboreal, swampy, or grassy ecosystem. Numerous terrestrial worlds displayed a variety of surface features, including exposed rock, freely available water, and verdant continental landmasses populated with plant and animal life. Others were solely composed of rock, rendering them barren and desolate. On certain terrestrial worlds, industrial or urban expansion had completely eliminated the original surface and ecosystem, resulting in an ecumenopolis.

Worlds such as Hoth and Mustafar exhibited extreme climates, yet still harbored life, with their inhabitants adapting to their respective environments. Certain worlds, such as Dathomir, were strongly connected to the Force, a mysterious energy field generated by life that united the galaxy. Numerous traditions suggested that lost worlds situated beyond the galactic frontier were among the pioneers in discovering the Force and its power. The term "Homeworld" was employed to designate the original home of a species, organization, or individual. For instance, Ryloth served as the homeworld of the Twi'lek species, while the human species was believed to have originated on the world Coruscant. The presence of a vast assortment of worlds containing a wealth of indigenous species, natural resources, and environments served as the primary impetus for the majority of travel, commerce, and conflict throughout the galaxy.

The destruction of a world was achievable, albeit requiring a formidable superweapon, such as a Death Star, which annihilated the world Alderaan. It was also feasible to transform a world itself into a superweapon, as exemplified by the First Order's Starkiller Base, constructed from the world Ilum, which possessed the capability to obliterate entire star systems, such as the ill-fated Hosnian system.