It is the most famous eclipsing variable star - it is the main representative of eclipsing variable stars with a subgroup of Algol type. Sometimes it is referred to as the "winking demon", which is related to its representation as the eye of Medusa. It was also depicted this way in ancient Greece, but there are no records proving that anyone noticed its light changes at that time. It was first observed by Italian astronomer Geminiani Montanari from Bologna in 1667, making it the only known variable star in the Middle Ages. Its true nature was correctly recognized by English astronomer John Goodrick in 1782.