O Moon (1990) is a lithograph on black paper by Nancy Holt, produced in an edition of 16. It is one of only two lithographs she created. While the moon is a recurring point of reference in Holt’s interest in light, celestial phenomena, and visual perception, O Moon is a rare work in which she represents the moon directly as an image. In 1972, Holt created Moon Book, a collaged fourteen-page book that brings together disparate relationships and perceptions of the moon across a wide span of time. One page includes an image sourced from an advertisement for the Questar telescope in the July 1967 issue of Sky & Telescope magazine; Holt returns to this image in O Moon.