The standard Federation system of planetary classification categorizes planets based on various factors such as atmospheric composition, surface temperature, vegetation and size. Each class is designated with a letter, for example, Class M (name based on the Vulcan terminology "minshara-class") is the most suitable for humanoid long-term habitation.
Planetary classes
| Class | Vulcan Class | Description | Examples |
|---|---|---|---|
| Class D | Planetoid or moon; uninhabitable | ||
| Class H | Generally uninhabitable | Tau Cygna V | |
| Class J | Gas giant | Jupiter, Saturn | |
| Class K | Adaptable with pressure domes |
| |
| Class L | Marginally habitable | Indri VIII | |
| Class M | Minshara | Terrestrial & Habitable | Earth |
| Class N | Sulfuric | Venus | |
| Class T | Gas giant | ||
| Class Y | "Demon" | Silver Blood planet |
Conjectural planetary classes
The Star Trek: Star Charts book, which was authored and advised by Trek staffers, lists many other planetary classes which may one day be recognized onscreen, but as of now they remain conjectural.
According to the Star Charts, a Class P planet is a 'Glaciated' planet. They have an age that ranges from 3 to 10 billion years and a diameter between 10,000 to 15,000 km. Class P planets are located in the ecosphere of a Solar system. A Glaciated planet is catagorized by a surface comprised of 80%+ water ice and an atmosphere consisting of nitrogen, oxygen and trace elements. Lifeforms found on Class P planets include hardy vegetation, animal life and occasionally native humanoids. It is widely believed that Breen is also a Class P planet. However, according to Weyoun, it is in fact a lush world with a temperate climate, in which case it would have to be categorized as Class M. (DS9: "When It Rains...")
Examples of a Class P planets: