Mirage

A mirage is a naturally-occurring optical phenomenon, in which light rays are bent to produce a displaced image of distant objects or the sky. The word comes to English via the French mirage, from the Latin mirare, meaning 'to appear, to seem'. This is the same root as for mirror. Like a mirror, a mirage shows images of things which are elsewhere. The principal physical cause of a mirage, however, is refraction and not reflection.

A mirage is not an optical illusion. It is a real phenomenon, and one can take photographs of it. The interpretation of the image, however, is up to the fantasy of the human mind.