Outer Colonies

The outer colonies are human controlled planets terraformed to support life. These colonies were formed later than the Inner Colonies for it took longer time to travel that far from earth. So humanity used the Inner Colonies to dock and refuel ships. It was possible to get to these systems by using the Shaw-Fujikawa Slipspace Drive engine. The outer colonies were the first targets (and victims) of the Covenant. Most of them were destroyed during the beginning of their genocidal war against humanity. In fact Earth first made contact with the Covenant when the outer colonie Harvest was destroyed.

Halo:Combat Evoled: Manuel "The story so far"