List the numerous types of planets found in the Mission : Illumination universe, with a focus on those not well known in normal astronomy.
Gas Planets Edit
Gas Titan Edit
Any planet more massive than a gas giant, but not exhibiting the qualities of a brown dwarf or proto-star. Most gas titans have a liquid metal or solid core, surrounded by layers of either liquid or highly pressurized gases, surrounded further by layers of ice particles or gas, and finally surrounded by clouds of gas, dust, or ice. Most known gas titans have satellites and rings, though some lack either satellites or rings, and in very rare cases, both.
Gas Complex Edit
Any gassy planet with a core that makes up more than 25% of the planet's volume, consists of 25% or more ice or liquid, and more than 25% gas by volume.
Gas Hybrid Edit
Any gassy planet with a core more than 35% of its mass, and more than 25% solid material (by mass) outside of the core (not inclusive of rings).
Ice Worlds Edit
Ice Giant Edit
Examples: Uranus, Neptune
A rather loose term used for massive planets with a similar structure to Uranus and Neptune, and also for planets larger than five earth which consist mainly (above 50% by volume) of elements heavier than helium in liquid and ice form. This term is a bit of a misnomer, as it was coined in the 20th century, before more accurate measurements could be made and more appropriate planetary categories were created. Today, the term Ice Titan is used more specifically for planets much larger than earth, that are true "Ice Worlds".
Ice Titan Edit
Any planet larger than five earth-masses with a solid ice layer over a small or low-density core and possibly also super-heavy element layers. They are differentiated from Ice Giants by their solid surfaces and lower surface gravity due to internal factors, and by the abundance of super-heavy elements not found in Ice Giants. Few notable ice-titans are known, and among them, only Friozha is permanently inhabited. Ice titans are unique among the planets in that they feature relatively low gravity (Friozha's gravity is not much greater than Earth's), but are rather high in mass and actual size, consisting largely of ice, liquid water, and gas. Most of the known ice titans orbit small, cool, young stars, and are about as cold as Antarctica on the surface, which is livable. However, Friozha is unique among the known ice titans, because it orbits rather far away from a Thionic Hypergiant star, and is so cold, its surface has rivers of liquid nitrogen during the winter.
Ice Colossus Edit
Any planet larger than 25 Earth masses with more than 45% ice content by mass or volume. As with Ice Titans, most known Ice Colossi lack a strong gravitional pull, due to a lack of core rotation, and sometimes due to magnetic dampening from super-heavy elements. Millitemprus has a surface gravity only 2.1 times that of earth, because its Tallium 42-shrouded core dampens most of its internal gravity.
Rocky Planets Edit
Any planet larger than five earth masses with a rocky surface, earth-like climate, and low enough gravity on the surface to sustain earth-born life. Most such planets have complex internal features that cause their surface gravity to be reduced significantly (such as heavily magnetized layers alternating or interspersed with force-dampening layers). Almost all known Hyper-earths feature super-heavy elements and their compounds, such as Lithium-Oolide, which have a dampening effect on natural forces such as gravity and magnetism.
Many hyper-earths are dotted with features called gravity wells. These are areas of the planet where gravity is much higher or lower than it is on the rest of the surface, and where other differences, such as especially powerful or completely missing magnetic fields, may also be noted.
Rock Giant Edit
Any planet larger than five earth masses, but consisting mainly of rock, lacking significant surface water, possessing a molten or rocky core, and not simply consisting of a aggregated materials. Most Rock Giants have intolerable surface gravity and are inhospitable to humans and most earth-born life.
Rock Titan Edit
Super Luna Edit
Any planet larger than Earth's moon, but with a roughly similar surface (with the exception of craters). This is a more loose classification that the others, as many planets could qualify for "Super Luna" status based on appearance alone. Most super lunar planets have an atmosphere, unlike Earth's moon, but lack the regular storms and other perils of other rocky planets with atmospheres. Most of them are relatively cold (in comparison to earth).
Recyclian Planet Edit
A type of planet unique to the Megachidnus System, as no similar planets have been found elsewhere. These planets feature a geological phenomenon called "Reclia", which consists of jets of water, gas and dust that form arcs in the atmosphere and return below the crust, following magnetic lines. Exactly how they work is a mystery.