Asterium is a star system in the Orion Spur of the Milky Way Galaxy. It is the capital system of Helios, a major human interstellar civilization.
The system lies near Cygnus-X, a large star-forming complex containing molecular clouds, ionised gas and associations of young, massive stars, including Cygnus OB2. Asterium is a separate inhabited system outside the complex's active star-forming clouds.