For the Egyptians, luck may have been written in the Demon Star
The blinking of a distant star may be chronicled in an ancient Egyptian calendar created more than 3,000 years ago to distinguish lucky days from unlucky ones.
Known today as the Demon Star, the three-star system Algol sparkles in the constellation Perseus, near the eye of Medusa’s severed head. Observers on Earth can see Algol twinkling when the two closest members of the system eclipse one another: Every 2.867 days, as the dimmer star crosses between Earth and the brighter star, the Demon Star’s light appears snuffed.
A repeating pattern of similar duration appears in the Cairo Calendar, a roll of papyrus dating to 1271 B.C. that characterizes each day as all good, all bad or a mix. The occurrence of all-good days matches Algol’s brightness fluctuations, researchers from the University of Helsinki report in a paper posted April 30 on arXiv.org.