Published in 1959, The Secret of the Ninth Planet is a science fiction adventure novel by Donald A. Wollheim, a central figure in twentieth-century American SF as both an author and the founding editor of DAW Books. The story follows a young American teenager drawn into an interplanetary adventure as alien forces secretly drain energy from the sun.
A fine example of midcentury American juvenile science fiction, the novel captures the optimism and sense of wonder that characterized the genre’s golden age. Download this free public-domain EPUB at Better Gutenberg.