Two Planets (German: Auf zwei Planeten, lit. On Two Planets, 1897) is an influential science fiction novel postulating intelligent life on Mars by Kurd Lasswitz. It was first published in hardcover by Felber in two volumes in 1897; there have been many editions since, including abridgements by the author's son Erich Lasswitz (Cassianeum, 1948) and Burckhardt Kiegeland and Martin Molitor (Verlag Heinrich Scheffler, 1969). The 1948 abridgement, with "incidental parts" of the text taken from the 1969 version, was the basis of the first translation into English by Hans H. Rudnick, published in hardcover by Southern Illinois University Press in 1971. A paperback edition followed from Popular Library in 1976.