It turns out that Ancient Egyptian Astronomers discovered an eclipsing Binary Star 3000 years before modern Astronomers did.
While many people believe that Italian Astronomer Geminiano Montanari discovered Algol in the 1660’s, it turns out that the star was discovered much earlier by the Ancient Egyptians. This discovery is proof that thousands of years ago, civilizations like the ancient Egyptians had the skill, knowledge and means to observe the cosmos with extreme precision.
Algol is actually a three-star system (Beta Persei Aa1, Aa2, and Ab) in which the large and bright primary β Persei Aa1 is regularly eclipsed by the dimmer β Persei Aa2. (Source)
According to a very badly damaged ancient Egyptian Papyrus, ancient astronomers from the land of the Pharaohs discovered the binary star Algol and knew the period of the eclipsing patterns of the Star, meaning that they were among the first astronomers on the planet to discover such a phenomenon and all of that thanks to naked-eye observations.
Researchers have come to the conclusion that the ancient Egyptian papyrus ‘Cairo 86637’ is the oldest preserved historical document of naked-eye observations of the variability of Algol or beta (β) Persei.
Research made by scientists from the Department of Physics and the Department of World Cultures of the University of Helsinki shows that the 2.85-day period seen in the Cairo Calendar is, in fact, equal to that of the eclipsing binary Algol, demonstrating that in ancient times, Algol was represented as Horus in ancient Egypt and was considered both divinity and kingship.
Scientists have concluded that the ancient text describing the actions of Horus are in fact identical with the course of events witness thousands of years ago by a naked-eye observer of Algol, which proves that this ancient Egyptian document is, in fact, the oldest preserved historical record of the discovery of a variable star.
According to researchers, each day of one Egyptian year was divided into three equal parts in the calendar. A good or bad prognosis was then specifically assigned for each part of the day, meaning that the calendar aimed to predict which days of the year would be lucky and which were not.
“The texts regarding the prognoses are connected to mythological and astronomical events,” says Master of Science Sebastian Porceddu.
“First of all, they discovered Algol 3,000 years before modern astronomers,” Dr. Lauri Jetsu, a researcher at the University of Helsinki in Finland and lead author of the study, told The Huffington Post. “Secondly, they used this information in constructing the prognoses of CC. The moon and Algol had religious meanings to them. Of these, the role of Algol is something completely new.”
Their naked-eye observations performed by ancient Egyptians allowed them not only to observe the star but to identify its regular dimming pattern.
“They probably noticed that their constellation containing Algol changed,” Jetsu said. “It is the star where it is easiest to discover periodic variability with naked eyes.”
“This variability was considered strange and threatening behavior from a star they considered a divine being,” Porceddu said. “We were rather surprised to find the period of Algol in the Cairo Calendar because it wasn’t known beforehand that this star would have had mythological properties to the ancient Egyptians.”