fata morgana

Fata Morgana is the Italian name for Morgan le Fay (meaning "Morgan the Fairy"), a sorceress of medieval legends. This sister of the legendary King Arthur is sometimes portrayed as the ruler of the island paradise Avalon and is said to have had a number of magical powers, with which she caused a great deal of trouble. Among her powers, say some versions of the legend, was the ability to change shape, and she has been blamed for causing complex mirages over bodies of water, especially in the Strait of Messina. Today we know that such optical illusions are really caused by atmospheric conditions, but we still sometimes use "fata morgana" as a synonym of "mirage."