The Demon Star

Low in the north-east, just below the "W" of Cassiopeia, there's a star slowly winking at us. It's the "demon star" Algol, in the constellation of Perseus. In a cycle of three days, it first dims, then brightens.

Ancient astrologers thought it the most unlucky star in the heavens and that any enterprise begun under its influence would come to ruin. Algol represents the head of Medusa, whose gaze, according to classical mythology, would turn men to stone.

 Medusa, known to most of us as a monster, was not only that way. Originally a beautiful maiden, she aroused the desire of Poseiden, king of the sea, and was raped by him in the temple of Athena. Athena, enraged at having her temple polluted, and unable to punish Poseiden (he was too strong for her,) punished the only mortal available: Medusa.

In fact, Athena went further. Not only did she transform Medusa into a hideous Gorgon, she also punished her two sisters (who were completely uninvolved!) the same way. So hideous were these Gorgons that their gaze could turn men into stone. So much for Greek justice.

Modern astronomers, in about 1780, deduced that Algol "winks" because it has a faint companion circling it. Every three days this companion would be exactly between Algol and the earth, partially eclipsing it. That's why it dims periodically.

Because of the glare of Algol itself, this companion has never been seen through a telescope. It can only be seen with the mind. Deducing its existence was one of the triumphs of modern science.

(09/17/08)