Ancient Egyptian calendar reveals earliest record of 'Demon Star'

Ancient Egyptians may have chronicled the flickering of a star known as "the Demon," perhaps the earliest known record of a variable star, astronomers suggest.

The ancient Egyptians wrote calendars that marked lucky and unlucky days. These predictions were based on astronomical and mythological events thought of as influential for everyday life. The best preserved of these calendars is the Cairo Calendar, a papyrus document dating between 1163 and 1271 B.C.

The scientists also detected another pattern in the calendar, one that occurred every 2.85 days. Now the researchers suggest this approximately matches regular dimming of Algol, "the Demon Star," which lies approximately 93 light-years away in the constellation Perseus as one of the eyes of Medusa's head. Its name comes from the Arabic phrase, ra's al-ghul, which means "the demon's head."

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