Cairo Calendar shows Egyptians discovered binary Algol first
(PHYSorg.com Space & Earth)

(Phys.org) -- Algol, aka the Demon Star, is actually a binary star in the Perseus constellation, and has been the subject of speculation for hundreds of years. Now a group of Finnish researchers propose that the peculiar behavior of Algol was first noted by the Egyptians some 3200 years ago. They suggest, as they describe in their paper uploaded to the preprint server arXiv, that a document known as the Cairo Calendar, shows that not only did the Egyptians know about Algol, but that their observations can be used to further explain the erratic behavior of the binary seen today.