Algol double star. Artwork of the stars in the eclipsing binary star system Algol (Beta Persei). This double star comprises a cool orange star and a smaller, brighter, hotter white star. The stars orbit each other in the same plane as seen from Earth. This leads to regular and periodical dips in the brightness of the system. When the orange star passes in front of the white one, the star dims considerably. It dims by a lesser amount when the white star passes in front of the orange one. The stars orbit each other every 2.87 days, and are separated by less than 15 million kilometres. Algol lies around 93 light years from Earth in the constellation Perseus.