1943, an ancient papyrus was bought by the Cairo museum.
It was written in Hieratic and although portions of it were eaten away by ants, it was a very precious ancient document.
The papyrus contained three separate books dealing with astronomy. One of the books was the Cairo Calendar, and now it reveals an ancient astronomical secret.
A research team from Finland is now suggesting that ancient Egyptians were familiar with the Demon Star and its odd behavior already 3200 years ago!
The period of the binary star Algol, was 2.850 days three millennia ago.
For religious reasons, the ancient Egyptians have recorded this period into the Cairo Calendar, which describes the repetitive changes of the Raging one. Cairo Calendar may be the oldest preserved historical document of the discovery of a variable star!
Ancient Egyptian scribes wrote Calendars of Lucky and Unlucky Days that assigned good and bad prognoses for the days of the year. The prognoses were based on mythological and astronomical events considered influential for everyday life.
The best preserved calendar is the Cairo Calendar (hereafter CC) in papyrus Cairo 86637 dated to 1271-1163 B.C.
Algol is remarkable in many ways.
It seemed to defy the general rule of astrophysics that more massive stars evolve faster, because the more massive Algol A has not evolved away from the main sequence, but the less massive Algol B has already evolved to the subgiant stage.
This famous “Algol paradox” was finally resolved only about half a century ago. Algol A was less massive than Algol B when this system was formed.
Algol brightens and dims every 2.867 days, a phenomenon first described in semi-modern western astronomy by John Goodricke, who wrote about what he saw with the naked eye back in 1783.
Although it is highly unlikely the ancient Egyptians could have known that the dimming was caused by one of the binary stars passing in front of the other, they recorded Algol’s unusual activity on regular basis. The Demon Star’s movements were described in the Cairo Calendar that has managed to survive over the thousands of years.
Ancient Egyptians were highly sophisticated astronomers who possessed knowledge that inspired them in their daily lives. Astronomical alignments also played a very important role in the orientation of ancient Egyptian temples.