Double exposure (photography)

Apollo 8 launch. The photo is a double exposure, as the Moon was neither visible at the time of launch, nor that phase (NASA)

In film and photography, double exposure is a technique in which a piece of film is exposed twice, to two different images. The resulting photographic image shows the second image superimposed over the first. The technique can be used to create ghostly images or to add people and objects to a scene that were not originally there. It is frequently used in photographic hoaxes.