Planetary Classification

Modifying Canon for the Modern World

Projects such as TRAPPIST and the Kepler Telescope have expanded our knowledge of the wide variety of potential planets. We have discovered worlds seldom considered by science before now: "Super-Earths," "Hot Jupiters," and "Ocean Worlds," we have come to understand are quite commonplace. We have also come to know that most stars likely have some planets, and that Type M and Type K stars are the most logical candidates for "Superhabitation"- long periods of habitability that will stretch into tens, even hundreds of billions of years. Reality has trumped some science theory as well- we are finding planets with orbits in binary star systems. Where science and science fiction seem farther apart (at least for now) is finding habitable planets around hot stars: A, B and O type stars. Here, Ulysses continues to take some creative license in the vein of Star Trek's model.

To try to keep up with this, the mods of the Ulysses sim decided to revamp Star Trek's traditional planetary classification system and try to expand it. There have been a few changes, and a little shuffling around. But we hope you will recognize the bones and features set forth by the franchise.

Planetary Classifications

The Ulysses sim has sought to expand upon the definitions of planets using the traditional classification system but also includes optional subtype decsriptors and size variants.

Class C (Carbonaceous)

The unique qualities of carbon make planetary bodies composed primarily of carbon compounds unlike those found with silica, iron-silicate, or water composition. Carbon sublimates- it moves from solid to gas- therefore only under extreme pressure and temperature would carbon gas behave in any way like a liquid. Tectonic activity cannot happen within a carbon-based world- carbon does not form its own version of magma. Carbon is also an active element that bonds with many different other elements, quickly fixing many building block materials we recognize as necessary for life into compounds completely alien or inconducive to life as humanoids known it. An irony as most life in the known galaxy is carbon-based but on these worlds where carbon dominates, it forms chemistry far different than most terrestrial worlds.

Carbon-dominated worlds almost never have expansive oceans or polar caps. Carbon is an active element that tends to absorb oxygen and hydrogen before it can form water. By the same token, very few carbon worlds have any appreciable level of oxygen.

Geoinactive Subtype

Geoinactive Class C planets are the carbon-dominant equivalent of a Class D planet. They tend to be very dark bodies, possibly with methane ices in regions where hydrogen was an abundant source during accretion. These subtypes may differentiate but the "classic" geoinactive body has little more than various carbon compounds to do so with. As pressures mount in the larger planets, these bodies may form crystalline cores of diamond, but also sublimate with thick carbon-based atmospheric compounds.

Ipsocrystalline Subtype

Ipsocrystalline subtypes are usually the Class C equivalent of a Chthonic Class D world. They are sometimes referred to as "Carbon Chthonics," but by far the more common moniker are "Diamond Planets."

Class D (Dead, Dormant)

A Class D world is a "dead" or "dormant" planet that has never had all of the necessary ingredients to support life as Humanoid beings know it. They may possess some of the necessary elements- water ice, traces of oxygen, organic compounds- but not in abundance enough to support life in the long term. However, life may have existed or exists in transience as space-borne life that inhabits these bodies as a habitat. A "classic" Class D world is an asteroid, dead moon, or a "round rock in space."

A Chthonic Subtype

Chthonic Subtype

Chthonic Class Ds may or may not have begun their lives as Class D. A Chthonic subtype is a world which has had its atmosphere and regolith (surface) blasted or eroded away either in a single event or over time. Many Chthonics are remnants of worlds which stray too close to a parent star, were subjected to intense solar winds, or else survived a nova event. As a result, most Chthonics are what remained of the planet's core materials, the densest and most resilient- often an iron or other metal core capable of generating magnetic fields. The effects that blew off their outer layers may have crystalized their outer surfaces.

Differentiated Subtype

Differentiated Class Ds are dead or dormant bodies with different elements and materials composing it. This subtype is large enough to have become (at least partially) molten which allowed the heavier elements to sink to the core and the lighter elements to remain near the surface.

Ferrous Subtype

Ferrous Class D can be undifferentiated or differentiated depending on their size. They are composed primarily of iron and iron silicates. They are noted, depending on size and interior deformation, for having magnetic fields.

Lithogelidic Subtype

Lithogelidic Subtypes of Class D are mixes of rock, metals, and ices. Usually, they are undifferentiated (and therefore tend to be small). Lithogelidic bodies can differentiate their materials, but pressures within are not usually enough to alter the planet's structure to become Lithopelagic. Most Lithogelidic planets are similar to Earth's moon- regolith with surface ice hiding in crater shadows.

A Lithopelagic Subtype

Lithopelagic Subtype

Lithopelagic subtypes of Class D planets are remarkably common. They tend to exist in the Goldilocks or Frost zone of a star. On the surface they appear very much like a Lithogelidic or standard Class D world. They may or may not have some surface ice. The difference between Lithogelidic worlds and Lithopelagic worlds is this subtype has differentiated materials. Under a solid regolith crust, increasing pressures have created liquid water "pockets" in the icy-rocky mantle. If life exists in these pockets, it is likely very different than most forms of terrestrial life. Such life almost certainly has ammonia or methane compounds dissolved in the water to retain its liquidity.

Selenic Subtype

Sometimes called "Scam-Type" Class D's, Selenic subtypes lack metals, instead being dominated by metalloids and inorganic compounds (such as sulfur and silicon). They tend to be low mass and never had a core capable of generating a magnetic field. Selenic subtypes can be dangerous as Arsenic and Polonium are both toxic metalloids.

Undifferentiated Subtype

Most undifferentiated subtypes are small- asteroids. These bodies are not large enough to have generated the heat and pressure necessary for differentiation (separating light and heavy materials into layers). Undifferentiated bodies are conglomerates of many different materials, but those materials never moved within the body to form a crust or core. Larger undifferentiated subtypes are rare and usually happen because something happened to rob the body of its heat and pressure.

A Class E Planet

Class E (Elastic/Exothermic)

Class E worlds can theoretically be found throughout a solar system, though the vast majority will be located in the terrestrial, rocky zones of the inner system. A broad category, Class E covers very young worlds which will reclassify into any number of planetary types, but Class E also includes some perpetually resurfacing, heavily bombarded worlds- and worlds simply so close to their stars that their surfaces remain partially or completely molten. Some Class E worlds are beginning differentiation through pressure, while others may have active, roiling molten cores that have not yet calmed enough to allow a continuous rocky surface. The defining characteristic of Class E planet is persistent, widespread lava and magma activity on the surface.

Archaean Subtype

Archean Class E worlds are the youngest planets on scene- these are the worlds still undergoing active accretion within their systems. Subjected to nearly constant bombardment by stellar material, Archaean worlds have a stunning array of appearances. Most possess hydrogen and helium atmospheres of various densities, as the stellar winds have not blown off their "first generation" atmospheres. Archaean worlds appear as a mottled mixture of cool and molten rock, often obscured under clouds and atmosphere, while others may have clarified atmospheres (without clouds). Archaean worlds are also known as "Protoplanets."

Bracatoactive Subtype

Bracatoactive Subtypes are Class E worlds that are undergoing an active bombardment phase from debris within the system. Bracatoactive and Archaean worlds are differentiated by age and by the source of bombardment. While Archaeans are still forming from local protoplanetary disc material, Bracatoactive subtypes are thought to have formed fully as planets and have cleared their orbital field. However, outside gravitational forces (or the gravity of the Subtype) continues to draw heavy bombardment. Bracatoactive planets have partially molten surfaces.

A Coronal Subtype

Class H (Harsh)

Class H worlds are generally habitable, at least in part, but have reduced resources or favorable elements compared to a Class M world. Harsh planets often lack water, have thin but breathable atmospheres, extremely turbulent and destructive weather, or else have wild temperature swings. Life can and does spring from such worlds, but tends to be hardy, homogeneous (alike) and located in the most habitable pockets of the planet. Because so many Class H worlds possess life forms and ecosystems already, they are seldom considered for terraformation. Class L and Class H worlds have some similarities, the criteria being that Class H worlds have pockets or zones of habitability whereas most Class L worlds are universally less conducive to humanoid life.

Sitic-Diluvic Subtype

Often coinciding with a Furenic subtype, Sitic-Diluvic Harsh worlds have an atmospheric phenomenon that fails to distribute precipitation in a predictable or consistent manner. These worlds have regional extremes of flood and drought, imperiling crops and life forms with too little water, or else massive flooding that reduces the ecosystem's long-term viability. These random cycles are affected by long-term climate but are also unpredictable in seasonally; storms or droughts may give little warning.

Fictillic Subtype

Fictillic worlds are rare: through some previous or ongoing geological process, massive stretches of the planet's terrain is composed of densely packed clays with poor nitrogen penetration. These clays make sustaining plant life almost impossible.

Non-Custodic Subtype

A Non-Custodic Subtype of Class H is a world that lacks a magnetic field. This exposes any life forms to the effects of stellar weather and atmospheric depletion. Such planets tend to suffer from excess (but not immediately lethal) ultraviolet radiation.

Selenic Subtype

Selentic subtypes of the Harsh world classification have extensive but not immediately lethal deposits of potentially poisonous metalloids- arsenic and selenium are most common.

A Superpaludal Subtype

Superpaludal Subtype

Superpaludal Harsh planets are unusual. From orbit, they may appear as quite ideal. However, the extensiveness of their low-lying landmasses is to such an extreme that most of it is under seasonal or tidal marshes, swamps, or inundation. Sometimes called "Mudballs" these worlds see more than 85% of their landmasses as so low lying that it cannot deal with stagnant water, runoff, or high tide. There is no protection for freshwater from saltwater invasion, often making the former brackish.

Class M (Minshara/Habitable)

Class M worlds, or Minshara in the Vulcan planetary classification system, are near-Earth like and generally habitable. However, they come in a wide variety of subtypes and compositions. The criteria for a Minshara class is that it must have a breathable atmosphere for baseline humanoid life, must have tolerable temperate zones conducive to plant and animal life, and must have liquid water to sustain biological life forms. Most Minshara class worlds exist in the "Goldilocks Zone" of a parent star, a swath of potential orbits that allow for liquid water.

A Calidic Subtype

Calidic Subtype

Calidic planets are hot for their classification and could be steaming jungles with saturated humidity, or baked deserts, yet they retain enough water and habitability to avoiding slipping into Class H or Class L status. Such worlds would be, by Earth standards, "Hothouse" or "Greenhouse" worlds.

Furenic Subtype

Furenic worlds of the Class M type are noted as having large, long-lasting and particularly powerful storm and wind events. Their atmospheres tend to be turbulent.

A Gelidic Subtype

Ampliseismic Subtype

An Ampliseismic Subtype of the Minshara-class has more seismic activity than most worlds of the same class- more volcanic or earthquake activity. This can be a natural phenomenon of the planet and often denotes that the planet is habitable but still geologically young. Or there could be deeper issues- uneven core pressure or material distribution can threaten the long-term habitability of the world.

Amplitectonic Subtype

While tectonic activity is very common on most habitable worlds, Amplitectonic Subtypes have, for some reason, dozens if not hundreds of smaller crustal tectonic plates, causing increased tectonic plate motion (which leads to seismic and volcanic activity) as well as rapid turnover of crustal geology.

Gelidic Subtype

Gelidic Class M Worlds are locked into persistently cooler temperatures, creating expanded continental and oceanic glaciation. While not yet a Class P "Snowball Earth," a Gelidic world is near-permanently in an "Ice Age."

Geodormant Subtype

Geodormant Subtypes of the Minshara are habitable worlds that are destined to pass into the Class G classification. Their cores and mantles have begun the process of solidification, and the internal heat engine is beginning to shut down. In all likelihood, the world's magnetic field is also beginning to collapse.

Gracilic Subtype

Gracilic Class M worlds have thin but breathable atmospheres. They may have close-hugging atmospheres with sea-level-like conditions that rapidly become unhabitable at higher terrains, or else the sea-level atmosphere of the planet is similar to 2,000 meters (or more) above sea level on Earth.

Iugosic Subtype

Iugosic worlds have extremely mountainous terrain, often rapidly rising from any sea, ocean or lake. Such worlds tend to create varied "pocket climates" forming habitable valleys but have very little land at sea level. Iugosic worlds are (or were) almost always seismically and volcanically hyperactive. A large percentage of Iugosic worlds are geologically "young."

Lacustric Subtype

Lacustric Class M worlds have most of their surface water locked up in rivers, lakes, and inland seas. Such worlds have very few (if any) expansive oceans.

A Lutosic Subtype

Lutosic Subtype

Lutosic Class M worlds have thick atmospheres that usually obscure much of the planet's surface, and have increased air pressure. Often these worlds have dense and humid atmospheres. Habitability to a Human comfort level can likely be attained at a higher elevation. Lutosic subtypes may have plants, but those plants likely rely on a source of energy other than the sun. Lutosic worlds are also (usually) observed to have low light levels.

Paludal Subtype

A Paludal Subtype

Paludal Class M worlds are noted for having a high percentage of low-lying, near or at sea-level terrain which is often marshy or swampy. More than 75% of the planet's land is low-lying.

Pelagic Subtype

Pelagic Class M worlds are approaching Class O status and have surfaces dominated by oceans to a degree that 85% of the surface is under water.

Suptic/Cenotic Subtype

These unusual worlds possess Class M environments below the planet's surface- usually in extensive cavern systems. A great deal of the planet's water is subterranean but accessible in nature. The surface of such a world may or may not be conducive to life, but has a breathable atmosphere.

Tundric Subtype

Tundric Class M worlds are not Class P and are not Gelidic, but are prone to or in the process of entering an Ice Age.

Vadumic Subtype

Vadumic Class M worlds have unusually shallow oceans, often less than a kilometer deep, and at least 25% of the ocean is under less than 100m of water.

Xeric Subtype

Xeric subtypes of Class M planets are arid for the standard and have less surface water than the traditional Minshara class. They are not yet defined as Class H.

Class O World

Class O (Oceanic)

Class O planets have all the elements conducive to life as most humanoids understand it. The main criteria for Class O status is that 85% or more of the planet is covered in water. Such worlds vary widely but otherwise meet Minshara requirements. Such worlds are different than Class W worlds- they are terrestrial worlds with rocky-metallic cores whereas Class W worlds are large bodies of differentiated liquids.

Acidic Subtype

Acidic Class O planets are rare. Their oceans, despite the name, are habitable to life but the pH balance is closer to rain, freshwater, or brackish water than to saltwater found in traditional oceans. Deeper portions of the ocean could be more in line with saltwater norms, but the salts aren't ubiquitous enough in the ocean to alter the surface waters quickly. Some of these planets have hydrospheres that are so saturated that it rains almost all the time, reinforcing the freshwater quickly. Acidic subtypes are otherwise meet the same criteria as a classic Class O.

Bathypelagic Subtype

Bathypelagic worlds are Class O planets in every respect. Their dry land amount to fifteen percent or less of the surface. What makes Bathypelagic worlds so unique is the incredible depth of their oceans. Such worlds may have very little continental slope transitioning from land to abyss. Most have comparatively little- even no- shallow waters. But at their core, Bathypelagic worlds have oceans with depths in excess of dozens of kilometers unseen on Earth. Despite this, Bathypelagic worlds are still terrestrial worlds- they possess rocky and metallic cores.

Calidic Subtype

Calidic Class O worlds can be mostly (85%) or completely (100%) covered in ocean. What differentiates them is their "greenhouse" or "hothouse" climates. These worlds are hot and humid on a scale unseen on Earth. Water vapor has a high percentage of the atmosphere's composition. The heat generated from these worlds can push some of the Calidic subtypes into the Furenic subtype, and the two often go hand in hand. Such worlds may have abundant rainfall and fresh water, but none of it is trapped in ice. Most of these worlds have water that would be too warm for conventional Earth lifeforms, but many have life of their own genesis. It is rare but not unheard of for tidally-locked or otherwise hot worlds to have zone where the water may approach a near-boiling state (but in all likelihood, the temperate and polar regions, or leeward side of the planet to the sun regulate this).

Furenic Subtype

Summavadumic Subtype

Summabathyian Subtype

Summabathyian world subtypes are 100% covered in water- no landmass breaks the water level. The depth of the "world ocean" is enough that the entire globe is "open sea:" the planet has extremely deep oceans that never allow land to come close to the surface. Such worlds do not have "shallow waters" and may possess ocean depths unseen on Earth- dozens of kilometers. However, Summabathyian worlds are still terrestrial and possess rocky surfaces- they are simply under a great deal of water.

Summapelagic Subtype

Summapelagic subtypes of the Class O worlds identifies a rocky, terrestrial body with 100% water cover- no landmass breaches the water level. Summapelagic worlds may have zones of relatively shallow, coastal waters.

Summavadumic Subtype

Summavadumic subtypes are terrestrial planets with 100% water cover, but the oceans tend to be quite shallow- less than a kilometer in depth. Though fully inundated, the planet may have regions that are under as little as a few meters of water and much of the planet is under less than 200 meters of water.

Tidal-Paludal Subtype

Tidal-Paludal planets are, for most of the time, covered in at least 85% ocean. However, external forces acting on the planet- a moon, a nearby gravitational body, a trojan world, or the Tidal-Paludal body being a moon itself- creates tidal forces that briefly expose large amounts of landmass (usually for a few hours). Conversely what little land it may have could be inundated by coastal waters as tides change for a similar period. Therefore, any above-ocean landmass on Tidal-Paludial worlds is tenuous and may be partially or completely submerged (or partially retreated from) according to the external factor causing the tides.

Ultrasalinated Subtype

Ultrasalinated Class O worlds are little different than other Class O planets on the surface. They are at least 85% covered in water. The unusual factor is that, below a certain ocean depth, the oceans become so salty that it forms a type of brine. Life finds increasingly alkaline waters too poisonous to exist in for long. Life that tries to enter such depths tend to enter a form of toxic shock. Some native life forms do evolve to exist in such environments.

Vadumic Subtype

Vadumic subtypes of the Class O designation meet the criteria that 85% of the planet is covered in water. However, Vadumic worlds have universally shallow oceans and bodies of water. Their oceans are less than one kilometer in-depth and almost 25% of the planet's oceans are under less than 100m of water.

Class P (Polar)

Summagelidic Subtype

Summagelidic Class P's are the classic "Snowball Earth." 100% of the planet's surface is covered in ice all year. Continental ice shelves dominate the entirety of the land, and oceanic ice has managed to entirely close in the planet's ocean (the ocean itself is still liquid under the ice).

Class T (Toxic)

Toxic worlds are not conducive to life as Humans and most humanoids understand it. They have geological or atmospheric chemistries that are hostile, harmful, or lethal to most known life forms. Life has been found on such worlds (such as atmospheric archaeobacteria on Venus) but it is seldom recognized as compatible with a life matrix Humans are a part of. Toxic worlds vary widely, classified by their compositional elements more than the features of their terrain. Class T worlds can be found in every orbital zone around a star, but begin life as terrestrial (rocky) bodies. They may have thick or thin atmospheres and may or may not have metallic cores enough to generate a magnetic field.