From Paizo's site:
This 64-page softcover explores the solar system of the Pathfinder campaign setting. Along with extensive gazetteers and maps of each of the numerous planets of this system (including the war-torn Red Planet of Akiton, the undead world of Eox, the primeval Green Planet of Castrovel, gas giants, asteroids, moons, and more), this book includes guidelines for traveling from world to world and exploring the dark depths of outer space. Rules for several new monsters, alien races, and magic round out the otherworldly offerings.
by James L. Sutter