The Aquarius Formation was a name given by Federation scientists to a large collection of astronomical objects which were located about a 1,000 light years from Federation space.

In 2273, Admiral Heihachiro Nogura assigned the USS Enterprise to voyage to the Formation, and chart the unexplored territories leading up to the formation. When the Enterprise returned to Federation space in 2280, they had charted hundreds of planets and dozens of stellar phenomena. (TOS novels: Crucible: Provenance of Shadows & The Fire and the Rose).

It has been noted by editorial staff that the Crucible novels have disregarded other, earlier non-canon works, as artistic license by the writer. These would take place in a different continuity than other stories, which represented that the Enterprise participated in a second five-year mission and remained close to Federation space.