aka Sol IX
Pluto is considered gameplay-wise to be the ninth planet in the Sol system (though in the real world it is no longer considered a planet). It is a Pellucid World, and has 125 Resource Units to mine in the form of a single deposit of 5 Tzo Crystals.
Pluto not only is the furthest planet from the sun (most of the time), but also has the smallest size, the coldest temperature, the weakest gravitational pull, and the most elliptical orbit of all the planets. The Spathi captain Fwiffo, last of the Ur-Quan's Earthguard forces, is found hiding here in his Eluder vessel StarRunner.