Lucky Starr and the Moons of Jupiter

Lore & Background

The novel takes place in the Jovian system. In the mid-1950s, when the novel was written, Jupiter had twelve known satellites. The first half of the novel takes place on what was then the outermost known satellite, Jupiter IX, discovered by Seth Barnes Nicholson in 1914. Jupiter IX had been given the unofficial name 'Hades' in 1955, but in the novel Asimov mistakenly refers to it as Adrastea, which was the unofficial name of Jupiter XII. The confusion arose from the fact that Jupiter IX was the twelfth farthest known satellite, while Jupiter XII was the ninth farthest. In 1975, the International Astronomical Union gave Jupiter IX the official name Sinope. Asimov describes Jupiter IX as being 89 miles in diameter, but its diameter is now thought to be only 23 miles. Part of the novel is also set on Io, the innermost of the Galilean moons, depicted as having a thin atmosphere of methane, fields of ammonia snow and ice, and rivers of liquid ammonia.

Reader's Guide

The novel introduces the Sirians as villains in fact, following their earlier appearances as distractions in previous series entries. The Three Laws of Robotics plays a part in the novel, revealing Asimov as the true author, though for the sake of continuity the novel was published under the pseudonym 'Paul French'. There are small inconsistencies between the various novels: the first man on Mars is named Ching in Moons of Jupiter, whereas in David Starr, Space Ranger he is named Wingrad; the name of the state that rules the Solar System changes from novel to novel, here being the Solar Federation of Worlds. The novel was reviewed favorably by Galaxy's Floyd C. Gale, who called it the best of the Lucky Starr series, and by Villiers Gerson in The New York Times, who declared it to be 'well-written adventure'.

Did You Know?

• The novel mistakenly refers to Jupiter IX as Adrastea, which was the unofficial name of Jupiter XII.
• Jupiter IX was given the official name Sinope by the International Astronomical Union in 1975.
• The novel features a robot spy disguised as a German Shepherd dog named Mutt.
• The Three Laws of Robotics appears in the novel, revealing Asimov as the true author.

Publication and Place in Asimov's Bibliography

Lucky Starr and the Rings of Saturn closes out the six-volume juvenile science fiction series that Isaac Asimov wrote under the pen name Paul French. Doubleday & Company released the book in 1958, and it marked a quiet but significant endpoint in Asimov's publishing history: it would be his last novel to reach readers until the 1966 novelization of Fantastic Voyage, and his last wholly original novel until The Gods Themselves appeared in 1973. That nearly fifteen-year gap between original novels makes the Saturn book a kind of bookend, the final word Asimov spoke in the voice of his younger-audience persona. The title also singles it out as the sole Asimov novel whose action unfolds within the Saturnian system, distinguishing it from the Jupiter-focused entries that dominate the rest of the series. For fans cataloguing the author's output, the book occupies a unique niche: a juvenile adventure that is simultaneously a career milestone and a one-off in terms of setting.

A World Built on 1950s Astronomy

The novel's stage is the Saturnian system, rendered with the best astronomical data available in the late 1950s. At the time of writing, only nine moons had been catalogued, with Mimas serving as the innermost. Asimov assigns Mimas a diameter of 340 miles, a figure that modern measurements have since revised downward to roughly 240 miles. Several chapters unfold on Titan, which in the 1950s was ranked as the third-largest moon in the Solar System, trailing only Ganymede and Triton; today we know Titan actually holds the second-largest spot behind Ganymede. The novel's Titan breathes an atmosphere described as nearly as dense as Earth's and composed primarily of methane, whereas current science tells us its atmosphere is actually denser than Earth's and consists of 98.4 percent nitrogen with just 1.6 percent methane. The story's final act shifts to the asteroid Vesta, which Asimov correctly identifies as the brightest object in the asteroid belt. He gives Vesta a diameter of 215 miles, but modern measurements place its mean diameter closer to 330 miles. These gaps between 1958 knowledge and present understanding give the book a charming, dated texture that modern readers can appreciate.

The Titan Dispute and the Vesta Conference

Six weeks after the Jovian-system adventure, David "Lucky" Starr is drawn back into interstellar politics when Jack Dorrance, the escaped chief of a Sirian spy ring, flees toward the Saturnian system. Starr and his companion Bigman Jones pursue him, but Dorrance's vessel is shattered by a fragment of Saturn's rings. The crisis escalates when the Sirians reveal they have established a colony on Titan and formally claimed it for their star, directly challenging the long-standing principle that a stellar system belongs indivisibly to its inhabitants. Starr initially orders the Terrestrial fleet home, then returns with Bigman and Councilman Ben Wessilewsky. After hiding inside Mimas and leaving Wessilewsky below its surface, Starr is captured and brought to Titan, where Sirian commander Sten Devoure coerces him into a false testimony. The conflict is ultimately resolved at an interstellar conference on the asteroid Vesta, where Starr's carefully planned revelation—that Wessilewsky was deliberately placed on Mimas to establish Earth's claim—turns the Sirians' own sovereignty argument against them. The vote results in the Sirians being ordered to vacate Titan within a month, cementing the "Indivisibility of Stellar Systems" as galactic law.

Sputnik's Shadow and the Sirians as People

Asimov drafted the novel between December 1957 and February 1958, in the immediate wake of the Soviet Union's launch of Sputnik I. That geopolitical anxiety surfaces in chapter 8, where Starr reflects on Sirian-built robots and insists that their creators are human beings whose achievement belongs to all of humanity: if Earth fears the result, the proper response is to match or surpass it, not to deny the worth of the accomplishment. The passage reads as a direct, if allegorical, commentary on the space race. The book also stands apart in the series as the only installment in which Sirians appear as actual characters rather than as robots or Earth-based agents working on their behalf. This gives the conflict a more personal, face-to-face quality. Like its predecessor Lucky Starr and the Pirates of the Asteroids, the novel places Earth on the brink of war with Sirius, and on both occasions Starr's intellect averts catastrophe on the grounds that full-scale conflict would bring ruin to both civilizations. The recurring theme underscores Asimov's conviction that diplomacy and clever thinking can outperform firepower.