The 100 planets described in Sector Two are all a part of a single cluster - the curious astrological entity known as Roarde's Diadem. Here two vigorous, expanding religions are held in precarious balance by the Imperial House of Cavoral.
From the inside page:
Spacefarer's Guide to Planets: Sector Two is a science-fiction role-playing game aid. It is designed to fit most science-fiction role-playing game rules:
Although the cover names this Spacefarer's Guide to Sector Two, the list inside clearly states that it is titled Spacefarer's Guide to Planets: Sector Two to complement Spacefarer's Guide to Planets: Sector One.