Planetary Classification System

The planetary classification system (PCS) is a system of categorizing planets based on their features that was pioneered by the V.R.A. New planetary definitions are constantly being added, as planets that do not fit the existing criteria are discovered. Unless the planet is specifically marked as a given subtype, it is assumed to be a relative mixture of all of them.

Planet Classes
There are several primary types of planets under the current version of the PCS: Gaia, oceanic, desert, ice, volcanic, barren, and gas giant. In addition, each primary type has a number of subtypes.

Gaia
Planets classified as "Gaia" are typical habitable planets. They have a variety of ecosystems, and variable precipitation throughout the year. They usually, although not always, have at least one satellite. Gaia-type planets are also usually home to abundant wildlife, unless it is too early in the planet's life cycle for it to support much in the way of animal life. Gaia-class planets have three different sub-categories, used when the umbrella term "Gaia" does not fit. These are forest, mountainous, and oceanic. These planets are usually rich in a variety of resources.
 * Forest: Forest planets are very similar to the main "Gaia" label, but are usually covered primarily by vegetation, rather than having a variety of ecosystems. The vegetation can be of any type, whether boreal, sub-tropical, or tropical.
 * Mountainous: Mountainous planets are similar to planets to which just the label "Gaia" has been applied, but feature a greater amount of height variation. There is usually less surface water on mountainous planets than other types of gaia-class worlds. Most of the mountains on these planets are still located below the local treeline.
 * Oceanic: Oceanic planets are similar to standard gaia-class worlds, but have 70-90% of their surface area covered in water.

Oceanic
Planets under this classification have more than 90% of their surface covered in water. Land, if it is above the surface at all, is limited to a few island chains or perhaps a small continent. These planets are prone to violent storms, especially hurricanes, and rainstorms can often last for months. If the planetary climate is cold enough, icebergs are common. Oceanic planets have two subtypes: island and continental. These planets are usually poor in accessible resources, as it is difficult to mine the ocean bed.
 * Island: Simply means that all landmasses take the form of small islands, usually the tips of tall underwater volcanoes or mountain ranges. There are no landmasses larger than a few square kilometers.
 * Continental: Simply means that most of the landmass is concentrated in one place, with possibly a few small islands around it. Continental oceanic worlds are rare, when compared to the other types.

Desert
Desert worlds are fairly simple: Bone-dry, with little to no surface water or precipitation. Any life would consist of hardy shrubs and plants, and possibly some small lizards and mammals. Large mammals are rare on desert planets. There are three different subtypes of desert planets: rocky, sandy, and saltpan. Desert planets are usually fairly resource-rich, although setting up mining operations may be problematic due to the sand. Some also have a thriving tourism industry.
 * Rocky: Rocky deserts are characterized by numerous sandstone formations, as well as great canyons and mesas. Rock arches and other seemingly delicate formations are typical as well. The sand on these types of planets, if there is any, is much coarser and of a larger grain than on other desert planets.
 * Sandy: Sandy deserts are the classical "dune sea" deserts, where the dunes extend all the way to the horizon. Dunes can reach several dozen meters in height, and the sand is usually a very fine powder.
 * Saltpan: Saltpan deserts are usually a variation on the rocky desert, although sandy saltpans occasionally occur as well. The saltpans, which are the remains of ancient oceans which have since evaporated, are the typical characteristic of these planets, and can be many thousands of kilometers across and several deep.

Ice
Ice worlds are simply planets that are in the middle of an ice age, or are permanently frozen due to the low atmospheric temperatures. These planets are characterized by thick snowpack, water bodies frozen to hundreds of meters deep, and subzero temperatures for most of the year. There is little life, either plant or animal, in most cases. There are three subtypes: glacial, snowy, and mountainous. These planets are usually poor in accessible resources, as temperature and dense glacial ice prevent much meaningful extraction.
 * Glacial: Glacial worlds are usually in the middle of an ice age, and are characterized by massive blocks of ice moving across the landscape. These planets usually remain uninhabited, as structures tend to shift from year to year.
 * Snowy: Snowy planets have few glaciers, but are instead covered in snowpack dozens of meters thick.
 * Mountainous: Mountainous planets have a greater level of height variation than other ice worlds, and are generally characterized by large and violent avalanches. Glaciers are also common.

Volcanic
Volcanic worlds are very young planets which are still in the process of forming. Earthquakes, massive volcanic eruptions and lava flows, and rich deposits of all manner of resources are typical characteristics of volcanic planets. Depending on the amount of surface water, the vulcanism can be either on land or underwater. This is one of the few planet types with no subtypes.

Barren
Barren worlds are just that: barren. No vegetation, no animal life, and a landscape composed entirely of rock. These worlds usually have little water, and most often little atmosphere either. Primary terrain features are massive craters, mountain ranges, and canyons. This category has two subtypes: rocky and acidic. These planets are usually rich in resources.
 * Rocky: Rocky worlds are the typical barren planet, whose primary features are large craters, mountain ranges, and canyons.
 * Acidic: Unlike most barren planets, these have an atmosphere, but it is usually composed of acidic compounds, and potent acidic rain is common.

Gas Giant
Gas giants are large planets whose atmospheres are usually composed of methane and other, more exotic chemical compounds. They have no actual surface, and the air pressure is usually enough to compress most objects to many times smaller than their original sizes.