of Saturn. Neutronium Brennan created an 8 ft diameter sphere of neutronium, a material consisting of densely packed neutrons. The sphere had a surface gravity of eight million g and was maintained within a stasis field at his world of Kobold. Kobold Kobold is the man-made world that Jack Brennan created out at the edge of the Solar System from raw material using his advanced intelligence as a Protector and his human sense of whimsy, complete with an artificial ecosystem. Kobold was Brennan's home for over 200 years. It was destroyed at the departure of Brennan and Roy Truesdale from Kobold. Kobold would appear to be named after the Kobolds of German folklore, spirits that people believed to be mischievous tricksters at times, and at other times prayed to for protection. This role fits Jack Brennan's dual nature as a trickster (using his superior intellect to baffle humans on Earth) and as a self-appointed Protector of Humanity. Timeline of events 2.5 m.y.a. — Settlement of Earth by Pak colonists. 33,000 BC — Phssthpok departs Pak homeworld. 32,800 BC — First emigration wave departs Pak homeworld. 32,500 BC — Second emigration wave departs Pak homeworld. 32,500- BC — Pak scouts depart Pak homeworld. 2125 AD — Phssthpok arrives at Sol. Brennan turns protector. 2340 AD — Kidnap of Truesdale. 2341 AD — Discovery of Pak fleet. Departure of Flying Dutchman. Destruction of Kobold. 2346 AD — Discovery of Phssthpok's Star. 2350 AD — Arrival at Home. Reception Sidney Coleman reviewed the novel favorably in F&SF; although describing it as really "two long novelettes passing as a novel," he noted that "both halves of the book are permeated with the ingenuity that has been the driving energy of Niven's stories since his earliest work." See also Planets in science fiction References External links Protector at Worlds Without End "The Adults" at the Internet Archive 1973 American novels 1973 science fiction novels American science fiction novels Ballantine Books books Novels about impact events Known Space stories Fiction about main-belt asteroids Novels by Larry Niven Novels set on Mars