Researchers have determined that ancient Egyptians were well aware of the variability of the Algol triple star system thousands of years before modern astronomers after studying the Cairo Calendar, which documents this star system's brightness.
As Phys.org reports, the Cairo Calendar has also been called the Calendar of Lucky or Unlucky Days and was determined to have been written between the years 1244 and 1163 BC.
This special calendar would have allowed Egyptians to learn what days were either favorable or unfavorable for them by assigning particular days, and even certain times during these days, as either good days or bad days.
But besides allowing ancient Egyptians the opportunity to decide whether certain days would be good or not, the Cairo Calendar was also found to have had an astronomical function, which included ascertaining the changing brightness of Algol.
The new study on this star system, Algol as Horus in the Cairo Calendar: the possible means and the motives of the observations, was written by Joonas Lyytinen, Perttu Kajatkari, Jyri Lehtinen, Jaana Toivari-Viitala, Sebastian Porceddu, Lauri Jetsu, Tapio Markkanen, and Joonas Lyytinen and analyzes how the beliefs about Set, the god of chaos, and Horus, the falcon-headed god, were also utilized in the calendar.Despite the discovery of the Cairo Calendar, researchers are still unclear as to who first began documenting the lucky and unlucky days along with the astronomical events that were witnessed by Egyptians thousands of years ago. However, the ancient scribes who concocted the special calendar did appear to believe that the objects in the sky that they were seeing, including Algol, were related to their gods.
Specifically, according to study author Sebastian Porceddu, Algol would have been related to Horus and the activities of this particular Egyptian god.
"The discovery of Algol's variability would have to be dated to thousands of years earlier than has been previously known. The star would have been a part of ancient Egyptian mythology as a form of the god Horus."The new research on the Cairo Calendar also lists 10 specific arguments that describe how the scribes of this calendar, who are also referred to as "hour watchers," would have had very good reasons to have documented the changing brightness of Algol.
The new study which describes how ancient Egyptians understood the variability of Algol thousands of years before modern astronomers, which was documented in their Cairo Calendar, has been published in Open Astronomy.