Ancient Egyptian Calendar Reveals Earliest Record of 'Demon Star'

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 “Demon Star” lies in the constellation Perseus as one of the eyes of Medusa’s head. The constellations are shown here in Johannes Hevelius’ “Perseus” from Firmamentum Sobiescianum sive Uranographia (1687). CREDIT: Public Domain)
“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 entry for each day is prefaced by three hieroglyphics that indicate either good or bad luck, with the characters often derived from events of mythology. Astronomers at the University of Helsinki in Finland had previously discovered that some of the fortunate days recurred in a pattern, every 29.6 days. This almost exactly matches the length of the lunar cycle — the time between two full moons. New moons may have been associated with bad luck.”
“The scientists also detected another pattern in the calendar, one ...