World Class

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The River of Heaven Flows Ever Onward...

This content is a part of Local Universe.

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Overview

The World Class, also known as the International Galactic World Classification System is the most prominent classification system of worlds in the Local Universe. The World Class is primarily used to classify all sorts of planets and moons into their own respective classes.

Terrestrial Worlds

A terrestrial world, terran world, or rocky world is a planet or a moon that is composed primarily of silicate rocks or metals. They are among the most common types of worlds, next to gaseous worlds. Like every other type of world, terrestrial worlds form in the accretion disks of forming stars.

Oceaniae

Basic Overview

By definition, an Oceania or a Water World is a type of terran world or a moon wherein the surface is completely covered by water, and a substantial portion of it's mass is water. During world formation it occurs that icy worlds move inward (i.e., toward the star) as they form. Inward migration presents the possibility that they move to orbits where their ice melts into liquid form, turning them into ocean worlds.

In some oceaniae more than 10% of the total mass is water. These worlds have oceans hundreds of kilometers deep. Their abyssal depths are so deep and dense that even at high temperatures the pressure turns the water into ice. The immense pressures in the lower regions of these oceans can lead to the formation of a mantle of exotic forms of ice. This ice is not necessarily as cold as conventional ice.

If the world is close enough to its star that the water reaches its boiling point, the water becomes supercritical and lacks a well-defined surface. Even on cooler water-dominated worlds, the atmosphere can be much thicker than average, and composed largely of water vapor, producing a very strong greenhouse effect. Such worlds have to be small enough not to be able to retain a thick envelope of hydrogen and helium, otherwise they would form a warmer version of an ice giant instead.

Classification

Oceaniae are classified into five distinct classes, according to their oceanic depth.

• Epipelagic Class: Oceaniae in this class are dominated by shallow waters that go up to two hundred meters in depth. This is one of the rarest classes of oceaniae and the most likely to develop life.
• Mesopelagic Class: Typically the oceaniae in this class have oceans that can range from around two hundred meters to one kilometer in depth.
• Abyssopelagic Class: The oceanic depth of abyssopelagic class oceaniae can range from one kilometer to twenty kilometers. In these worlds, the fauna is typically limited to deep sea
• Hadalpelagic Class: The most common class of oceaniae, the aquatic depth of hadalpelagic class oceaniae typically ranges from twenty kilometers to one hundred kilometers deep. Most hadalpelagic class worlds have no multicellular life to speak of, as a side effect of the great pressure at these oceanic depths.
• Stereopelagic Class: Stereopelagic is the deepest class for oceaniae, being above a hundred kilometers in oceanic depth. In these depths, the immense pressure causes the formation of exotic types of ice, such as Ice VII

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  Epipelagic Class: 1 meter to 200 meters
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  Mesopelagic Class: 200 meters to 1 kilometer
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  Abyssopelagic Class: 1 kilometer to 100 kilometers
• Hadalpelagic Class: 100+ kilometers
  Hadalpelagic Class: 100+ kilometers

Habitability

Oceaniae are one of the most potential worlds for multicellular life to develop. Most of the time, life starts to develop in deep-sea thermal vents, first in the form of microscopic organisms feeding off of the material spewed by the thermal vents. Over a long amount of time, the lifeforms would evolve into a more complex ones, likely similar to many deep-sea fish or octopus species on Earth. This life would, in some cases, evolve to thrive in more shallower waters, until they are essentially flourish in the sunlight zone of the ocean. Most of the time, however, life is limited to the deep dark abyss, unable to ever reach the upper oceans, living in eternal darkness.

Down there, many species would evolve to emit light either by bioluminescence or biofluorescence. This is an effective way to find a mating partner, scare off predators, or attract prey. Many creatures would also be affected by deep-sea gigantism, essentially making them larger to combat asphyxiation, and be more effective in the dark. Unable for photosynthesis to happen, all of the deep sea environments on oceaniae would have no plant-life. The closest thing to flora would be deep-sea corals, which are actually invertebrate animals. The aforementioned lack of plants would prompt all deep-sea species to evolve to be purely carnivorous.

Gas Worlds

By definition, a gas world, also referred to as a gaseous world is a planet or a moon that lacks a solid, well-defined surface. Gas worlds rival with terrestrial worlds in terms of rarity. Gas worlds, like all other types of worlds, develop in the accretion disks of young and still-developing stars.

Gas Giants

Classification

Gas giants are split into five classes (numbered using Roman numerals) according to their modeled physical atmospheric properties.

• Class I: gas giants in this class have appearances dominated by ammonia clouds. These worlds are oftentimes found in the outer regions of a planetary system. They exist at temperatures less than about 150 K.
• Class II: gas giants in class II are too warm to form ammonia clouds: instead their clouds are made up of water vapor. These characteristics are typical for planets with temperatures below 250 K . Even though the clouds on such a planet are similar to those of terrestrial planets, the atmosphere consists mainly of hydrogen and hydrogen-rich molecules such as methane.
• Class III: gas giants with equilibrium temperatures between 350 K and 800 K do not form global cloud cover, because they lack suitable chemicals in the atmosphere to form clouds. These planets appear as featureless blue globes because of Rayleigh scattering and absorption by methane in their atmospheres.
• Class IV: Above 900 K, carbon monoxide, rather than methane, becomes the dominant carbon-carrying molecule in a gas giant's atmosphere. These worlds form cloud decks of silicates and iron deep in their atmospheres.
• Class V: For the very hottest gas giants, with temperatures above 1400 K the silicate and iron cloud decks are predicted to lie high up in the atmosphere.

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  Class I: ammonia clouds
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  Class II: water clouds
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  Class III: cloudless
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  Class IV: alkali metals
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  Class V: silicate clouds

Habitability

It is not uncommon to find gas giants that host unicellular or even multicellular life. To understand why the birth and subsistence of life is possible in the atmospheres of gas giants it has to be taken into account that there are factors which greatly inhibit the formation of complex organisms, but also factors that increase the likelyhood of biogenesis and abiogenesis on these planets. An inhibiting factor is the existence of convective currents that constantly transport material between different layers of the atmosphere. Life adapted to the conditions of one atmospheric layer could be transported into another, where it might decompose due to excessive temperature and pressure. This process is referred to as pyrolysis and is a big obstacle to the formation of organic life. Despite these difficulties the variety of different niches and the sheer size of the available reaction volume paired with vast periods of available time favor the formation of life-forms that are able to adapt to the convective currents. Due to parallel evolution organisms that thrive on different gas giants share some basic similarities. Generally, they can be divided in to four categories:

• Floaters: Organisms that actively keep their pressure level and stay in the same atmospheric layer for a relatively long period of time.
• Sinkers: Organisms that reproduce before falling into the lower layers and decomposing in a pyrolytic process.
• Hunters: Organisms that seek out other biota to either prey on them or mate with them.
• Scavengers: Organisms, similar to floaters, that spend most of their existence in the lower layers almost at pyrolytic height and consume the organic compounds generated by the pyrolysis of other organisms.

Of course it also possible that organisms alternate between these "roles" during their lifecycle.