Dark Moon is a science fiction novel by American author Charles W. Diffin. Mysterious, dark, out of the unknown deep comes a new satellite to lure three courageous Earthlings on to strange adventures. Dark Moon is part of the Harkness-Bullard sequence, Dark Moon (1931), Brood of the Dark Moon (1931) and The Finding of Haldgren (1932) involving adventures on an errant new planet full of monsters which has been captured as a new moon orbiting Earth. Dark Moon was first published in Astounding Stories in May 1931. Charles W. Diffin (1884-1966) was a US engineer, airplane salesman and science fiction writer. He was one of the better writers whom Harry Bates encouraged to write for the new Astounding Stories.