View of a "Demon Class" planet.
In planetary classification a Class Y planet is a 'Demon' planet. A Demon planet is catagorized by a surface where the temperature can exceed 500 Kelvin and an extremly turbulent, toxic atmosphere with thermionic radiation. In rare cases, biomimetic lifeforms (Silver Blood, in that instance, in 2374) have been found on Class Y planets; the only recorded example of this was found on a planet in the Vaskan sector by USS Voyager. (VOY: "Demon"; "Course: Oblivion")
- Information taken from Star Trek Star Charts indicates class Y worlds have an age between 2-10 billion years and a diameter between 10,000-15,000 km. They can be located anywhere within a solar system.