Planets are a constant in the universe. There are many different types of planets and moons. With the expansion of the human race, a classification system had to be created. The following is a list of all the types of worlds in the universe.
The largest planet type, this gaseous planet type is similar to Jupiter or Saturn. J-Class planets normally have a lot of hydrogen and helium within their atmosphere which normally take up around 90% of the planetary mass.
N-Class are gaseous giants similar to Uranus or Neptune. The planetary atmosphere of an N-Class has a lot of various ices in the atmosphere such as water and ammonia. Hydrogen and helium constitute only about 10-20% of planetary mass. Water and ammonia are in solid form and under immense pressure in the planetary interior. They are usually smaller than J-Class planets.
An S-Class world, also known as a Selena, is a world similar to Luna during the early ages of human space exploration. A rocky lifeless world this type normally has no atmosphere at all. The world is normally pockmarked with asteroid impacts due to its lack of atmosphere.
A D-Class world is one with a planetary desert similar to Mars and Venus before terraforming. These type normally have an atmosphere which causes the rocks and dust on the planet to be tossed around by the winds of the planet. They are susceptible to dust storms.
An I-Class world is a world similar to a world like Europa, Ganymede, or Callisto before terraforming. These worlds are made mostly of and covered entirely in water ice. They normally have no atmosphere like an S-Class and also show signs of bombardment. Some I-Class worlds have inner liquid water oceans.
A T-Class world is one similar to an I-Class but the only major difference is that it has an atmosphere. These worlds are similar to Titan before terraforming began. Some can have some liquid oceans, lakes or rivers on their surface but it would likely be liquid methane or something else.
An E-Class world, also known as a Terra, is a rocky world with an atmosphere that has liquid water on its surface. Earth is a prime example of a natural E-Class world. Humans are well suited to adapt on E-Class worlds.
An O-Class world, also known as an Oceania, is one with a global ocean. All O-Class worlds have an atmosphere. A prime example of a natural O-Class is Ikusos. Some O-Class worlds can have small portions of frozen ice on their surface.
Theorized in the early days of space exploration but not truly discovered until the mid 21st century, these worlds have been ejected from their star systems and wander the interstellar medium without a star. Bellerophon, parent planet of Aleion, is an example of such a world.
Aside from the above classifications, there is a temperature qualifier involved for the mean temperature of any planet. There are 7 types of classification types which are listed below.
Anything above 527 °C
127 °C to 527 °C
27 °C to 127 °C
-23 °C to 27 °C
-73 °C to -23 °C
-173 °C to -73 °C
Anything below -173 °C
0.990 Planet Class (For people with 0.990)
J-Class: Also known as Jupiters, these gaseous planets are similar to Jupiter or Saturn, although some may be larger. Their atmospheres are mostly composed of hydrogen and helium. They are also the most likely to have a moon with terrestrial life.
N-Class: Known as Neptunes, these planets are gaseous like J-classes, but N-class planets are slightly smaller and have compounds such as ammonia and methane in their atmospheres. Some include Uranus and Neptune.
S-Class: This type of planet has no air. Some examples include pre-terraforming Luna and Mercury. SCART v0.990 gives these planets the prefix “airless”.
A-Class: These worlds, labeled as “desertic” or “arid” have no planetary ocean and are entirely covered land, similar to pre-terraforming Venus or Mars.
L-Class: Called “lacustrine” by SCART v0.990, These planets have small, disconnected oceans similar to large lakes.
M-Class: M-Class planets are similar to Earth. They have notably large oceans that cover 50-99% of the planet. They are given the prefix “marine”.
O-Class: These worlds, similar to modern-day Europa, have one planetary ocean. SCART v0.990 dubs these planets either “oceanic” or “superoceanic” depending on how deep the ocean is.
Subclasses for Terrestrial Worlds:
Subclass a: These worlds, initially called T or I-Class worlds, are rocky worlds made up mostly of ice and methane. Labeled as aquarias, these planets can be classified as Sa, La, Ma, and so on.
Subclass f: With SCART’s update, there are now more classes of terrestrial planets. One such is the ferria. These planets are mostly composed of iron. They can be Sf, Lf, Mf, and so on.
Subclass e: These planets, also known as terras by SCART v0.990, are mostly made up of silicates. Earth is one of these. The terras that do not have any carbon will likely have silicon based life, as carbon based life has an easier time forming. Earth is a Me-Class planet.
Subclass c: Also called carbonias, these planets are worlds highly abundant in carbon. These planets can be classified as Sc, Lc, Mc, and so on. Contrasting terras, these planets are expected to have life slightly more often.