Algol is traditionally identified with Medusa’s eye in the constellation Perseus. Its name comes from the Arabic phrase meaning “the demon’s head,” reflecting the star’s association with the Gorgon’s head.
Algol is a variable star whose brightness changes noticeably over a regular cycle. Ancient and medieval sky traditions connected the constellation Perseus with the hero holding Medusa’s severed head, and Algol marked the head or one of its prominent features.
Algol is a multiple-star system, and its apparent variation is caused mainly by eclipses within the system. The primary star is periodically dimmed when a companion passes in front of it. This made Algol an important object in the history of variable-star astronomy.
The astronomical identification is symbolic rather than a claim that Medusa existed as a celestial object. Star maps preserve the mythological image by placing the Gorgon’s head in Perseus’s hand.