Arcturus Station is the gateway to Sol, a 5-kilometer diameter "Stanford Torus"-type space station at the trailing Lagrange point of the gas giant Themis. Construction on Arcturus Station began in 2151 and concluded in 2162. It was inaugurated in 2156, and has served as the military and political headquarters of the Systems Alliance from the First Contact War until the present.
When humanity activated the Charon Mass Relay in 2149, it led to Arcturus, 36 light years from Sol, Earth's sun. Arcturus is the third brightest star seen from Earth. It is an ancient red giant from the generation born before Sol. Its worlds are either gas giants or ice chunks. While some rocky debris exists, the metal content is 25% lower than normal. To build Arcturus Station, metallic asteroids were towed through the mass relays to the construction site. Many of these asteroids remain near the station, their mined out areas home to transient populations.
The expense of bringing construct materials into the system was acceptable due to its strategic value. With three primary mass relays in addition to the secondary one to Sol, Arcturus is a major communications and military chokepoint. The Alliance 1st Fleet is based in Arcturus, where it can guard the gates to Sol and react to incursions in the three connected clusters. The Station also hosts the Systems Alliance Parliament and the Systems Alliance Military general headquarters. Its permanent population is approximately 45,000.
Arcturus is actually from the galactic halo, one of a cluster of 52 stars that are "crashing through" the disc of the galaxy. In a billion years, Arcturus will be sailing through the depths of extragalactic dark space.