This is the song "Sacred Icon Suite 2" from the Halo: Legends Original Soundtrack.

The following is a crosspost from the HBO forum, in a discussion started by Cody Miller about retcons of Halo's continuity by the latest game in the series, Reach. Some fans (namely Hawaiian Pig) take exception to David "Evil Otto" Candland, Bungie UI Designer, saying canon arguments aren't important. The image is from another post of Cody's, seemingly showing that Installation 04 isn't located in the Milky Way galaxy any more.

After reading part of this thread at HBO and finding myself in agreement simultaneously with HP and Evil Otto, I had another series of thoughts about how works are viewed by their creators, as opposed to their fans.

A work like Halo is not the creation of a single person, even if some people contribute more to some aspects of it than others. It is also not a static thing. While certain key concepts may endure from the start of brainstorming until the declaration of a Golden Master, many of the details may be in flux for months or years. Listening to the commentary by Jones, Staten and O'Donnell for the cutscenes of the first two games, it becomes apparent how different the series might have been if Bungie had made different decisions.