Jonathan Swift's Prediction

Jonathan Swift predicted the discovery of Phobos and Deimos "...which revolve about Mars; whereof the innermost is distant from the centre of the primary planet exactly three of his diameters, and the outermost, five; the former revolves in the space of ten hours, and the latter in twenty-one and a half...". You can download Gulliver's Travels from the Project Gutenberg website.