Earth

From The StarCraft 2 Wiki

Earth is the origin of the Terran race, with all Terrans being the descendants of human space colonisation efforts centuries before. Terran colonists came to the Koprulu Sector and set up three major societies: the Confederacy, the Kel-Morian Combine, and the Umojan Protectorate. Earth is not a member of either of these alliances, it is the basis of power for it's own faction, the United Earth Directorate.

Space Navigation [e]
Space:	Koprulu Sector | Sara system
Planets:	Aiur | Char | Chau Sara | Earth | Korhal IV | New Folsom | Mar Sara | Moria | Shakuras | Tarsonis