TerrestrialGroup E, F, G (10-15k km),
H (8-15 kkm) desert, L (10-15) barren,
M,
N (10-15)venus/reducing gases,
O (10-15)80%water, P (10-15)>80% water,frozen.
Q (4-15)(could be some of the dwarf terrestrials) variable star or eccentric orbit, XYZ
rocky ,
mass 0.02 - 5.0 Earth.massive enough toclear out their orbital zones and/or sustain continuous geological activity. This activity also maintains asubstantial atmosphere.
Proto-Active
proto-planetary,
still forming. (Class E?/G?)
surfaces often partial to completely molten,
atmospheres typically thick with hydrogen and helium, as well as gasesreleased by the massive geological activity; they still suffer major impactevents.
In general, ages < between 10 - 100MYO. Prior to this, the Terrestrial bodies are still accretingmass at a very high rate, and after this point the surface, though still occasionally experiencing majorimpacts, has largely cooled, forming the earliest crust.
Proto-Lithic, ,Class F
surfaces extremely hot or evenmolten.
composed primarily of silicates, common in mostsystems.
retain atmospheres of varying densities,
rich in hydrogen and helium.
Proto-Carbonian, ,
surfaces extremely hot or even molten.
carbon-rich,
fairly common,though they tend to appear more in high-massed systems.
atmospheres are typically rich with hydrogen, helium, andprimordial methane.
Proto-Gelidic, ,
surfaces hot,
high instances of geological activity.
Orbit outer regions of a solar system, and so theprimary building material is water.
may possesssignificant atmospheres and even regions of liquid wateron their surfaces as well, although as the world ages and cools, the atmosphere andliquid will freeze out, while the heavier silicates and metals will have sincesunk to form the body's core.
Epi-stellar,
tidally locked to stellar primary,
surface conditions made dynamic by geological activity, and/or atmosphericdynamics.
Jani-Lithic
rocky,
dry,
geologically active, greatly varying degrees of geologicalactivity.
atmospheres quite varied, but typically are primarily composed of carbon dioxide.
Vesperian (Class M, K, L) F
silicate worlds ,
continuous geological activity which may be plate tectonics, or a similar mechanism.
Orbit Close proximity to coolerlate k-type orM-typestars,
temperatures suitable for the development of life. And while a large number of circumstancesmust be met for these worlds to be life bearing, circumstances which are rare,the sheer number of stars which can host these worlds makes the presence of Vesperian planets only slightly lesscommon than Gaian worlds.
Jani-Vesperianposb L
atypical, borderlineVesperianworlds ,
either most of the surface water frozen out on the night-side,or the volatiles having been depleted during the planetary formationprocess.
native biology is sustained by the thickened atmospheres, but due to the lack of large bodies of water theysuffer major climatic extremes. Most surface water located in thetwilight regions, as well as the biomass.
Eu-Vesperian
mature Vesperian worlds ,
typically supportlush biomes.
Depending oncontinental configuration, and amount of surface water, there may be a night-side ice cap of varying size and thickness
the oceans and, to asomewhat lesser extent, the atmosphere aid in evenlydistributing the heat of the star across the globe, leaving only extremetemperatures under the star and near the night-side polar cap.
Bathy-Vesperian
high temperature ,
deep oceanic basins,
atmospheres quite dense. tend to have complete cloudcover, and a lack of any sort of night-side ice cap.atmosphere and ocean tends to evenly distribute global temperatures, althoughthere may be an oceanic "dead zone" near the surface directlyunderneath the star. Temperatures in this region caneasily reach nearly 250 degrees Fahrenheit.
Chlori-Vesperianposb L
biospheres that release free chlorine throughphotosynthesis.
can only form whenthere is a high percentage of hydrogen chloride in addition to the water.believed to be exceptionally rare, especially when taken with the relativerarity of Vesperianworldsthemselves.
Telluric,
conditions do notsupport a continuous hydrological cycle of any sort. typically subject tomajor resurfacing by literally cataclysmic eventsover the course of 700+ million years, although some may continue suchresurfacing at a slow but constant pace.
Because of theconstant geological outgassing, the atmospheres aretypically quite dense, and produce major greenhouse effects.
Phosphorian
most extreme of Telluric.
Orbit form much closer to their star than other Tellurics,
have correspondinglyhigher temperatures.
Because of theextreme solar heat, little to no cloud cover, although the atmospheres remain quite dense.
Cytherean (N: Venus)
archetypal Telluric,
trademark thick atmospheres formed by unrelenting geological activity and the buildup of major greenhouse gasesover 200+ million years.
While may form withan appreciable amount of water, the formation of this hot-house environmentwill eventually cause it all to evaporate and breakdown into its componentatoms.
Tectonic activity, which may have been in the formativestages, ceases, but the associated geology continues unabated. Eventuallythe build-up of gases produces incredibly dense atmosphere, whilethe volcanism thickens the crust, until a point is reached when volcanism mayactually become rare. However, a buildup of subsurface pressure isinevitable, and every ~300 million years the surface literally melts as themolten mantle boils up. Once this pressure has been globally released,the process of thickening the crust begins once more.
AridClass L
conditions support alimited but continuous hydrological cycle, and quite often an accompanying biosphere.
The geological activity of these worlds, coupled with theconstant recycling of carbon by that activity, aids in both keeping the planetfrom freezing, or from evolving into aCytherean world. it is often the evolved biology of the planet whichaids in maintaining its habitability.
Darwinian
Arid ,
< 30% surfacewater coverage, Most water is locked up within its biomass, which aids in maintaining global habitability.
lacking any kind of plate tectonics.
Saganian
ammonia equivalentsof Darwinianworlds, theplanet's water being mixed with liquid ammonia, the biomass fully adapted and dependent on its presence.
Asimovian
methane equivalentsof Darwinianworlds, watermixed with liquid methane, the biomass fully adapted anddependent on its presence.
Orbit: dimmer M-type dwarf stars.
Tectonic
Terrestrial, crustis separated into thinner and heavier oceanic crust, and thicker and lighterraised continental crust.
conditions support acontinuous hydrological cycle,
quite often anaccompanying biosphere.
Gaian (Class is ???) F
silicate-rich, ,
non-tidally locked,
continuous geological cycle , often quite geologically active.
Orbit tend to be located around stars ranging fromF8 V to K3 V, often in systemswith one or more large outer system Jovians.
usually 1/+ largemoons, which aid in stabilizing the planet's axial tilt, and thus supports astable biosphere.
Eo-Gaian
young Gaian,
age roughly between 800 myo and 3 byo,
rich and thick carbon dioxide and methane atmospheres.The presence of such a thick atmosphere,generated largely by methanogen bacteria, creates amajor greenhouse effect and a fairly active water cycle. atmosphericmethane forms thick layers of hydrocarbons in the upper atmosphere, coveringthe planet (appear) in an orange haze.
Meso-Gaian
Ageroughly 3 - 4 BYO,
Lifeprominent microbiological ecosystems.
atmospheres largely cleared of methane, although carbondioxide remains prevalent. As the present microbiological forms of lifebecome more complex and evolve, however, they begin to release oxygen into theatmosphere, slowly transforming the planet into aEu-Gaian state.
Eu-GaianClass M
mature Gaian ,
fully developed geological, hydrological, and biologicalsystems. Life usually quite diverse, although there may be caseswhere evolution beyond simple microbial forms never occurred, simply becausethere was no environmental pressure to do so. even in these cases, the life present produces oxygen and carbon dioxide as a bi-product,making the atmosphere unique and generally friendly for non-native lifeforms. In short, these are the archetypical"blue marbles"that are socovetously sought after by Humankind.
Gaian-XericClass L
warm and dry,
15/-% surface covered by standing water. Major desert zones common,
life tends to remain close to the small ocean and seabasins.
Plate tectonics present, but the relative scarcity of water meansthat this geological process moves slowly. Less water also means thatless carbon dioxide is absorbed and locked away into carbonate rock;
as such, the atmospheres are carbon dioxide rich and contribute to the overallhigher temperatures of these worlds.
Gaian-Campian
Surface 30-50% water coverage, oceans and seas tending tobe quite saline.
Temp Climatic extremes common, vast inland deserts notuncommon.
Due to the low watertable, biomass and atmospheric oxygen is muchlower in levels than with other Gaian worlds. effective absence of an efficient oceanicheat transfer system = large temperature differences betweenthe latitudes.
Gaian-Paludial
Surface 30-50% water coverage, land features tend to havelow surface relief, forming extensive swamplands, lakes, lushly forestedregions, and semi-open woodland.
climate predominantly oceanic, with relatively open oceanflow and freedom for globe-spanning weather systems to keep a largelyhomogenous planetary temperature. Polar regions do tendtowards glaciation, however.
geographical arrangement is typically due to a decrease ingeological activity, and tends to be common for lower mass, older Gaian worlds.
Gaian-Continental
Surface 50-80% water coverage, most of the planet's waterconcentrated within deep ocean basins.
arrangement ofcontinental plates can create a wide variety of climaticconditions across the globe, and these conditions change constantly as theplates continue to slowly drift over 2+ billion years
Gaian-PelagicClass Oand P, class M
Surface>80% water coverage, continental plateslargely submerged.
global climate is even and tends towards the temperate, although various circumstances can swing thatclimate to either the cold or the hot end of thespectrum. majority of the terrestrial regions are islands ormicro-continents located along rift or convergent zones.
Bathy-GaianClass O
could be regarded ascooler and relatively drier versions of Bathy-Pelagic, or very hot and high surface pressured Eu-Gaian.
Appear Superficially : similar to true Cytherean, their massive atmospheres consisting of carbon dioxide, and their surfaces concealed beneath dense cloud layers.surfaces are under 10-100 bars of pressure and 200-400 degrees Fahrenheit,although the high pressure keeps that water from evaporating. surface iscovered by a global ocean ~7km deep.
Life nearly always present, with more complex formsfound in the deeper waters. ocean bottom is barren and largely anoxic, but possesses itsown particular set of biomes.
Plate tectonics present, but continental crust almost entirelymissing.
Chloritic-GaianClass H (desert)?
quite rare ,
orbit usu around warmerG and cooler F-typestars.
typically little / no complex surface life, with most forms remaining in marineenvironments.
marked by largequantities of integrated chlorine in the environment, which is integral to any biomes present.
appearance, oceans and clouds somewhat greenish, whilecontinents usu somewhat barren brown.
Amu-Gaian,
15-85% ammonia oceancoverage
atmospheres methane-rich.
cold climates despite the presence of a greenhouse gas,with the ammonia content in the water aiding in keeping them liquid.
typically orbit coolerK and M-typestars.
Life can be present, but employs processes to balancethe mixed ammonia-water chemistry of their environments.
Thio-Gaian,
based on sulfurphotosynthesis rather than oxygen photosynthesis. The protein S8, whichis produced in photosynthesis, is carried to the upper atmosphere and shields the surface from radiation,
while the sulfuricacid which is also produced by this process is used to produce sulfur dioxideby plankton-like fauna-forms or microbes, which is thenproduced by other life forms, which in turn produce carbon dioxide and hydrogen sulfide as a wasteproduct.
These are then usedby the flora-forms to continue the cycle.
Appear: usu yellowish skies, and soil may be stained red from extensive rust deposits.
Gaian-Gelidian,
settled into a frozen climatic equilibrium, either due to biological or orbital placement reasons.
Complex life, if it develops, or remains extant, tends to beconcentrated within sub-glacial seas. However, if such a world hasentered into this state after the evolution of complex life, then that lifewill have most likely gone extinct.
atmospheres oxygen-deprived and nitrogen-rich. airusually devoid of major cloud formations, and with Aeolian forces beingdominant, the land areas will likely be barren of ice as pastglaciers will no longer have the means to grow, and their surface areas will bedesiccated by the wind.
Post-Gelidian, later exs:Class L
begun to lose largeamounts of surface water, typically due to the beginning of their star'sevolution off of the main sequence.
Early stages: dense,cloud-covered, water-rich atmospheres.
Often, plant life will undergo an explosion of diversity andgrowth.
Later examples of these worlds : largely desert, very restricted ,highly saline seas located in the lowest elevations. Life, if it remains,will be microbial extremophiles.
Amunian
carbon-rich, thus deprived of water, silicates, and otheroxygen-bearing compounds.
rich carbides, hydrocarbons, and other carboncompounds. soils are also rich in nitrogen.
Life forms not in water,then, which is rock-hard at the temperatures involved, but inliquid ammonia.
orbitM and K-dwarfstars, as the ultraviolet flux of anything greaterwould break down the planetary supply of ammonia. The term Amunian isderived from the Egyptian god Amun, from which the word 'ammonia' comes from.
Eo-Amunian
Age: young, atmosphere of gaseous ammonia,methane, small amounts of water droplets. As the planet ages and cools, these componentswill be broken down into nitrogen, carbon monoxide, and a hydrocarbon 'tar'that will rain down on the surface. Ammoniaoceans will condense on the surface during this period,and the earliest forms of life will develop. These organisms will beacidophilic due to the presenceof dissolved water, but they will begin converting the present oxygen intosulfur dioxide as a part of their metabolic processes.
Meso-Amunian
have cooled,
atmospheres composed almost entirely of nitrogen and carbonmonoxide.
primitive life will begin to use a hydrogen-methane cycle, thusincreasing the amount of methane within the atmosphere. Cycles whichincorporate nitrogen and carbon monoxide will also be used and eventuallyincorporated into the growing planetary ecology.
Temp As levels of methane increase the planet will onceagain begin to warm.
Eu-Amunian,
often considered tobe ammonia analogues of Gaian.
plate tectonics,
dynamic climate, differences in climate, hydrology, meteorology,and geology, all of which are significant.
sometimes anadvanced biosphere.
colder than Gaian,
orbit: forming beyond the habitable zone, (cold or hot?)
receive enoughenergy to melt ammonia. Because ammonia ice is denser than liquidammonia, polar caps are located beneath the polar oceans.
appearance : greener than Gaian, because of the gases involved, and their
atmospheres usu dense and rich in nitrogen, with significantamounts of methane and hydrogen.
Bathy-Amunian,
much strongergreenhouse effects than Eu-Amunian.
tmospheres very dense , retain large amounts of carbonmonoxide and 'humid' with ammonia. capable of supporting liquid ammoniaat higher temperatures because of the greater atmospheric pressure. maycontain significant amounts of volcanic and possibly sulfuric gases, dependingon the inherent geological activity. Large portions of the extant biomass located in the upper atmosphere, where it iscooler, as well as within the oceans and seas. Such organisms are extremophiles by the standards of the rest ofthe planet.
The extreme worlds,highest in pressure, can actually support liquid ammonia at temperatures whichare more common on Eu-Gaian.
Tartarian Class L
rich methane , carbon compounds.
Life forms not in water, which is rock hard at the temperatures involved, but in liquid methane.
Orbit: around dimmer stars, or in the outer regions ofSolar-type stars.
Eu-Tartarian
often considered tobe methane analogues of Gaian worlds.
plate tectonics,
dynamic climate, differences in climate, hydrology, meteorology,and geology, all of which are significant.
sometimes anadvanced biosphere.
colder than Gaian,
orbit: forming beyond the habitable zone, (cold or hot?)
receive enoughenergy to melt methane,
atmospheres usu dense and rich in nitrogen, with significantamounts of methane and hydrogen.
Oceanic, F, O
conditions support acontinuous hydrological cycle , global ocean that is 20+ kmdeep, many support advanced biospheres.
geologically active.geological processes involved tend to be more related to Telluric or Arid than Tectonic.
Pelagic F
silicate worldscovered with a global ocean.
typically foundaround warmK to cool F-typestars.
Eu-Pelagic
200+ times the waterfound on Eu-Gaian worlds.
atmospheres oxygen rich due to several ocean-relatedfactors. Some worlds have an oxygen content > 90%.
Bathy-Pelagic
highest water amounts,global oceans 20-200+ km deep,
atmospheres extremely dense. intense atmosphericpressure keeps the ocean liquid, and keeps it from boiling away. surfaceevaporation and re-condensation is so high that the demarcation line betweenocean and atmosphere is difficult to determine.
surface temperature can reach 200+ degrees Fahrenheit,
Pelagic-GelidianClass P
crusts: frozen over due to a variety of reasons, most often adimming star. Tidal or subsurface geological stresses often create cracksin the global ice coverage, allowing a
thin atmosphere oxygen , nitrogen to form. Were it not forconstant replenishment from these rifts, the atmosphere would desiccate within 3million years.
Nunnic global ocean ofliquid ammonia.
Teathic global ocean ofliquid methane.