Green ray is a rare optical phenomena that can be observed in the last or first sun rays, in particular weather conditions, on a distant horizon. The curvature and diffraction of light spectrum allows a clear perception of the green tones.
According to a Scottish legend, anyone who has seen this phenomena, obtain emotional enlightenment. This narrative has acquired many different shapes, as in the works of Jules Verne and Eric Rohmer, in which is translated into love stories.
Yet, most scientific reports mention long periods of waiting and attentive observation in order to witness the green ray, with the exception of the Portuguese navigator Gago Coutinho, who reported having been able to observe it repeatedly in the light of a distant lighthouse, inducing its demystification.