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.
- 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.