[The Nine Planets's] strong advantages are its easy readability, coherent story design, and relative absence of ambiguity or equivocation. Its faults probably are not too important, but a few are worth mentioning. The explanation of mean value (p. 4) is wrong. An alternate symbol (p. 8) for Uranus is still used by some astronomers. The term "minor planets" (p. 11) is not correct as a substitute for "terrestrial planets." Once again, Isaac Newton's illustration of orbital and suborbital speed is reproduced (p. 18) without credit. The geometric utility of Venus transits (p. 39) is no longer relevant, because the same information is available to much higher accuracy by modern means. The mass of Pluto is now known to be much smaller than previously believed. Also, the myth that Pluto is sometimes nearer the sun than is Neptune is perpetuated. There is a list of sources of further information, and a useful index is appended.