Sol is the star of the second Earth the Fleet is lead to after a Jump by Kara Thrace.
The coordinates to the third planet orbiting Sol were coded in a piece of music known to Thrace. After discovering humanoid life on this planet, genetically similar to the humans who evolved on Kobol, the Colonials settle this planet and decided to abandon all spacefaring technology. All ships incapable of landing on this new Earth are piloted into Sol by a Hybridized Samuel Anders (TRS: "Daybreak, Part II").