EarthSky Tonight—Algol, a famous variable star, dimmest tonight
Algol is what astronomers call an eclipsing binary star. In other words, the single point of light that we see as Algol is really two stars.
EarthSky Tonight—Oct. 30, As Halloween approaches, find the Ghoul Star of Perseus
This star’s proper name comes from the Arabic for head of the ghoul, or head of the demon.
EarthSky Tonight—September 17, Close-up on constellation Perseus the Hero and Demon Star
Thus, Algol is what has been called an “eclipsing variable star.”