Phlegethon (also known as Phlogiston) was the 2nd planet to be discovered in the Oribitus system. Located in 298 by astronomer Isaac Miller. Due to its high temperatures and lack of natural resources, it was not a point of interest for researchers. However, in the early 500s, several reactors were set up near the planet's surface, making it a semi-factory moon.

Phlegethon is the first planet in the Oribitus system.