One posssibility is that this is a double exposure of a living person. In 1959, this image would have been captured on film.
If it is not a double exposure and this is a spirit captured on film, then a number of questions arise: What is the entity looking and why? Do they have cameras and binoculars in the afterlife? Or is this an instance of a time slip in which the camera has recorded a scene from a different time?
It has even been speculated that this figure might actually be a time traveler or interdimentional being, who has been photographed in the act of watching us!