HELSINKI, Finland, Dec. 17 (UPI) -- Researchers have finally confirmed the ancient Egyptian's direct knowledge of variable star Algol and its periodic eclipses.
Algol is one of the best known eclipsing binaries. The pair is commonly known as the Demon Star, and can be found in the constellation Perseus. Eclipsing binaries are a pair of stars that rotate around a shared center of gravity. When they momentarily align, one star eclipsing the other, the stars appear to dim.
Researchers have previously speculated that ancient Egyptians observed the periodic dimming of Algol's binary system, but definitive evidence was hard to come by.
Recent analysis of a well-preserved ancient Egyptian calendar, however, offers the most convincing argument yet that ancient Egyptians observed and recorded Algol's eclipse.
The Cairo Calendar, CC for short, dates to between 1244 and 1163 BCE. Its contents include information about deities represented in the stars. Changes among the stars were interpreted as auspices.
Researchers at the University of Helsinki were able to show that Algol is linked with the mythological figure Horus. They also found direct correlations between the actions of Horus in mythological texts and changes in the brightness of Algol. These changes are reflected in periods of improving and worsening luck on the CC.
"We have presented evidence that the 2.85 days period in the lucky prognoses of CC is equal to that of the eclipsing binary Algol during this historical era," researchers wrote in a paper describing their discovery, published this week in the journal PLOS ONE.
Researchers acknowledge that skeptics will likely remain, but argue their latest analysis is more comprehensive than all previous studies.
"These descriptions support our claim that CC is the oldest preserved historical document of the discovery of a variable star," researchers concluded.