In 1975, Ellison asked a panel of well-known sf writers to construct an imaginary planet: Medea, a moon of a super-large, super-hot Jovian planet (which is itself orbiting a double binary star system). Hal Clement provided Medea's astrophysical data; Poul Anderson contributed geology and climate; Larry Niven, biology; and Frederik Pohl, the social backdrop. Another panel (Thomas M. Disch, Theodore Sturgeon, Frank Herbert, Robert Silverberg) debated and refined the ideas, sometimes interestingly. Fans were then offered the opportunity to comment and make suggestions. And finally they all went away to write stories set on their imagined planet. Jack Williamson fetchingly describes one of Medea's two intelligent species, the aerial ""balloons."" Larry Niven looks at how the Medean ecology has adapted to its unique biophysical circumstances. Harlan Ellison describes a vast ice sculpture; Frederik Pohl jokes feebly; Hal Clement writes about a murderous alien computer; Thomas M. Disch discusses religion and instantaneous communication; Frank Herbert provides a miniature version of his novel The Jesus Incident; Pohl Anderson attempts to create a bridge between the balloons and their hostile but intelligent rivals, the ""fuxes""; Kate Wilhelm examines another aspect of the balloon-fux interaction; Theodore Sturgeon invents a philosophy that brings sanity and peace; and Robert Silverberg wraps things up with a planetary earthquake. Disparate stories, only so-so on quality, plus overlong or irrelevant transcripts re the idea-in-progress: about what you'd expect of a book written by a committee--though the famous names here may prove alluring to some.