Substance

Substance is a greenish-blue gas giant in the Coelest system and it is the planet which Installation 05 orbits. In its colour, it is somewhat is similar to the planet Uranus, though it masses more.

Unlike on Installation 04, where its parent planet Threshold could be seen quite clearly, especially at night, on Installation 05, Substance is very difficult to see in the sky. In fact, in none of the locations on this ring seen by UNSC forces (namely the Control Room, the Library, and various ruined structures) can the planet be seen. This may suggest that Installation 05 has a denser atmosphere than Installation 04, or simply that these locations had thicker cloud cover at the time. Additionally, these locations could be positioned relative to Substance such that Substance is 'beneath' the ring, and thus impossible to see.

It is possible that Substance is host to a Gas Mining Facility similar to the one found on Threshold. The two planets are very similar, and they both are orbited by their own Halos.

List of appearances

 * Halo 2
 * Halo: Ghosts of Onyx