Basis

Summary
Basis is the largest moon orbiting the planet Threshold in the Soell system. The diameter of the moon is 23,848km. Installation 04 was positioned between Basis and Threshold. After Installation 04's destruction, the Covenant Heretics built a makeshift camp on Basis, amid the wreckage from the Alpha Halo.

Basis was mistaken for the location of the Gas Mine that was really on Threshold. Basis was the location of the Halo 2 multiplayer level Burial Mounds.

One fan claims that on The Silent Cartographer, Basis appears to have a face that looks like an angry Prophet.