Golarion is the primary world of the Pathfinder campaign setting, but it is not alone. Far beyond its lands and seas, sister worlds revolve around the same sun, their residents connected by magical portals or ships of terrifying magic and technology. Now take your game off-planet and explore these weird new worlds for yourself! This book offers a detailed introduction to the science-fantasy worlds of Golarion's solar system, each complete with its own mysterious locations and cultures. Discover how your swords and spells match up against the trench dwellers of the Red Planet or the angelic Sarcesians who soar between asteroids. Research the mysterious origins of the sealed world-ship of Apostae, or hunt vortex sharks in the freezing seas of Kalo-Mahoi. Though strange and new, each of these worlds uses the same Pathfinder Roleplaying Game rules as Golarion itself.