From Halopedia, the Halo wiki
Jump to: navigation, search
Substance and Installation 05. Distances are not to scale.


Coelest system



Orbital position:

Fourth planet





82,749 kilometers (51,418 mi)[2]


hydrogen, helium, methane
ammonia, water [2]

Substance, also referred to as Coelest IV[3], is a blue-white gas giant in the Coelest system. It is the fourth planet in the system and is the planet which Installation 05 orbits. Though it has a higher mass, it is similar to the planet Neptune in color and composition, being classified as an ice giant.[2] Substance is orbited by eight satellites, only one of which, Opusculus, is a natural moon. The rest include Installation 05, and six dormant Forerunner facilities on predetermined orbital paths.[2] An asteroid field was located close to Substance at 2.4 AU from Coelest.[4]

Unlike on Installation 04, where its parent planet Threshold could be seen quite clearly, especially at night,[5] on Installation 05, Substance is very difficult to see in the sky of Installation 05. 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 is due to the Delta Halo's stormy weather conditions caused by a Flood outbreak that occurred some two centuries before the Battle of Installation 05.[2] During the Great Schism that began on Installation 05, Sangheili and Jiralhanae vessels battled each other over Substance.[6]

Weeks after the battle and the subsequent Fall of High Charity, the UNSC Coral Sea picked up a dying San'Shyuum aboard a skiff drifting in a debris field irregularly orbiting Substance.[3]



List of appearances[edit]


  1. ^ Halo: The Essential Visual Guide, page 46
  2. ^ a b c d e Halo: The Essential Visual Guide, page 190
  3. ^ a b Halo Legendary Crate, Data Drop #8
  4. ^ Halo: Ghosts of Onyx, page 189
  5. ^ Halo: Combat Evolved, campaign level The Truth and Reconciliation
  6. ^ Halo: Ghosts of Onyx, page 199
  7. ^ Re: Halo Wikipedia entry improvement questions
  8. ^ Halo Encyclopedia, page 185