Editing Sagittarius Arm

{{Status|Canon}}

[[File:Milky-Way-labeled.jpg|thumb|300px|The Sagittarius Arm is named for its proximity to the [[Wikipedia:Sagittarius (constellation)|Sagittarius]] constellation when viewed from [[Earth]].]]

The '''Sagittarius Arm''' is a minor [[Wikipedia:Spiral_galaxy#Spiral_arms|spiral arm]] of the [[Milky Way galaxy]].{{Ref/Reuse|HW1213}} It lies between the [[Wikipedia:Scutum–Centaurus Arm|Scutum–Centaurus Arm]] further toward the galactic core and the [[Wikipedia:Perseus Arm|Persus Arm]] further toward the outer rim. The [[Orion Arm]], or Orion Spur, branches off from the Sagittarius Arm.{{Ref/Reuse|HW1213}}{{Ref/Reuse|HEPJC}}

The Milky Way's Sagittarius Arm was explored by the [[Forerunner]]s thousands of years ago and at least one [[shield world]], designated [[Shield World 10021|10021]], was constructed under the direction of [[Warrior-Servant]]s in a distal star system of this arm.{{Ref/Reuse|HW1213}} Prior to the [[Great Purification|firing]] of the [[Halo Array]] in [[97,445 BCE]], the [[Halo ring|rings]] known as [[Installation 01]] and [[Installation 07]] were transported from the [[Intergalactic space|extragalactic]] [[Installation 00]] to points in the Sagittarius Arm.<ref name="HW1213">''[[Halo Warfleet]]'', ''pages 12-13''</ref> Installation 01 was placed at the Array's Beta position distal to the offshoot of the Orion Spur and Installation 07 was placed at the Zeta position, proximal to Orion.{{Ref/Reuse|HW1213}} It was from these locations that Beta Halo and Zeta Halo killed every unprotected life form with even the most rudimentary of [[Wikipedia:Nervous system|nervous system]]s within twenty-five thousand [[Wikipedia:Light-Year|light-year]]s of each.<ref name="ENC184">''[[Halo Encyclopedia (2009 edition)]]'', ''page 184''</ref><ref name="HCETB">''[[Halo: Combat Evolved]]'', ''[[Two Betrayals]]''</ref>

Following a large [[2543]] [[Battle of Psi Serpentis|battle]] in the [[Psi Serpentis system]] between [[UNSC]] [[Battle Group India]] and two [[Covenant]] fleets, scattered reports of independent [[human]] forces fighting the Covenant began to pop up on the outer edge of what the [[Office of Naval Intelligence]] believed to be nonsanctioned human [[Human colonies|colonized]] space.{{Ref/Reuse|HEPJC}} These reports tracked toward the Sagittarius side of the Orion Spur.<ref name="HEPJC">''[[Halo: Evolutions]]'', ''[[The Impossible Life and the Possible Death of Preston J. Cole]]''</ref> Following the end of the [[Human-Covenant War|war]] between the Covenant and humanity, Installation 07 was discovered by humans a few years after the war and before long the UNSC [[Zeta Halo project|dispatched]] researchers to study it.<ref>''[[Halo: Hunters in the Dark]]''</ref>

The Sagittarius Arm holds a number of [[Forerunner]] [[Astroengineering|constructions]]. Proximal to the Orion Spur lies [[Installation 07]].{{Ref/Reuse|HW1213}} [[Shield World 10021]] can be found just beyond the Orion-Sagittarius junction and further beyond it is [[Installation 01]].{{Ref/Reuse|HW1213}}{{Ref/Note|A galaxy map featured in ''Halo: Warfleet'' places [[Shield World 006]] within the Sagittarius Arm. This is considered a liberty for the sake of visual presentation, as the [[Zeta Doradus system]]—which houses the shield world—is located well within the Orion Arm a mere 38 light-years from Earth.}}

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