World

A **Planet**, commonly referred to as **World**, is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. A system of planets orbiting a star could, under the correct conditions, be formed when drifting clouds of gas and dust beyond the star itself clumped together. Many scientists stated that a planet had to be large enough for its gravity to have 'cleared its orbit' by attracting all the smaller bodies in its immediate neighborhood, excluding its own satellites, known as moons. Additionally, a planet had to have a stable shape due to its gravity, becoming a regular, rounded ellipsoid, although some bodies that were known as worlds did not have a regular shape. Over time, the definition of a planet became more complicated, as scientists wanted to exclude near-stars, wandering rogue planets, dwarf planets, 'micro' planets, companion stars in binary star systems, bodies in asteroid belts and debris fields, and other objects.

Two main types of planets existed: gas giants and terrestrial worlds. Gas giants were mainly comprised of gaseous layers and did not have a solid surface. Normally, their atmospheres were mostly hydrogen and helium, although a few had oxygen-rich layers capable of harboring life. As very large planets, gas giants possessed powerful gravitational fields. The lower levels of a gas giant's atmosphere were at pressures able to crush any normal starship, and the center of most gas giants was a small, dense metallic core. Terrestrial planets were much smaller and very varied in nature. Many terrestrial planets did not have a rocky surface; some of these worlds were covered with water, which could exist as free-flowing oceans or permanent ice fields. On many other terrestrial planets, the rock had been broken down over time, providing a rich soil that supported a planet-wide arboreal, swampy, or grassy ecosystem. Many terrestrial planets had a range of surface features, including bare rock, free water, and green continental masses with plant and animal life. Others were purely terrestrial, making them barren and desolate. On some terrestrial planets, industrial or urban development completely removed the original surface and ecosystem, creating an ecumenopolis.

Some worlds have extreme climates and environments but still support life, like Hoth, Helghan, Catachan, and Mustafar. Certain planets, such as Dathomir, Tython, Korriban, and Ossus, were strong with the Force. The existence of a huge variety of planets that contained a wealth of native species, natural resources, and environments was the underlying reason for most travel, trade, and conflict across the galaxy.

The destruction of planets is a rare but common enough occurrence, either through natural occurrence, due to a supernova, a rogue planet crashing into a world, caught in the gravity of a larger planet and torn apart in time, or being sucked in and destroyed by a black hole or by the actions of sentient beings, though rarely did they ever truly destroyed the planet itself, as doing so would require a superweapon designed to destroy the planet itself, or more commonly, its' parent star, the most infamous of either for both types being the Death Star and the Nova Bomb, the former created by the Imperium, although it was destroyed not long after it was tested, and the latter had been developed by the Terran nationstates for millennia, though never used until near the end of the Second Terran-Sith War where it was used to destroy the star of the Dromund Kaas star system. But most often cases the way sentient beings destroy planets is through the use of bombardment of the surface of a planet to destroy its' biosphere either through nuclear, biological, chemical, microbot or turbolaser weaponry though the destruction of the physical surface of the planet is known to occur, as was the case with Korriban and other worlds subjected to the Imperium's infamous "Exterminatus" policy.

## Classification

There are over 4 trillion planets and 10 to 20 trillion moons and each other varied considerably from one another in terms of environment, climate, and biosphere. Each planet and or moon are unique but their similarities that sentient beings created classifications for the massive number of worlds that exist, either due to natural environments or their sentient-made environments. It should be noted that planets can belong to multiple classifications, for instance, Coruscant is both a Ecumenopolis and a Fortress world. Additionally, there exists a scientific category which correspond to the planet's environmental or sentient-made characteristics.