The Sol System is a star system in the Milky Way galaxy. With a total of eight planets and several moons, it is the home system of the human race and center of the United Citizens' Federation.


  • Mercury — Innermost planet. Uninhabitable.
  • Venus — Second planet. Uninhabitable due to an unbreathable atmosphere of sulfur.
  • Earth — Third planet. Homeworld of mankind and the United Citizens' Federation.
    • The Moon (luna) — Earth's natural satellite and UCF colony. Primary base for Fleet.
  • Mars — Fourth planet and UCF colony. Mining and mineral processing.
  • Jupiter — Gas giant.
    • Europa — Ice moon of Jupiter and UCF colony. In 2190, an expedition discovered that Europa contains an abundance of primitive plant life.
    • Io — Volcanic moon of Jupiter. Formerly a UCF colony for gas mining. A separatist movement called "Free Io" seized control of the base in 2199 and destroyed it before a resolution could be reached.
  • Saturn — Gas giant known for its distinctive rings.
    • Titan — Moon of Saturn. Defense station for the Sol System.
  • Uranus — Gas giant.
  • Neptune — Gas giant.
  • Pluto — Dwarf planet. Mining and SICON listening post. Location of first contact with the Arachnids.