3,200-Year-Old Papyrus Contains Astrophysical Information about Variable Star Algol

Dec 23, 2015 by Sergio Prostak

Ancient Egyptians wrote Calendars of Lucky and Unlucky Days that assigned astronomically influenced prognoses for each day of the year. The best preserved of these calendars is the Cairo Calendar dated to 1244 – 1163 BC (Ramesside Period). According to scientists at the University of Helsinki, this papyrus is the oldest preserved historical document of naked eye observations of a variable star, the eclipsing binary star Algol.

The Egyptian Museum of Cairo purchased this unique hieratic papyrus from an antiquities dealer in 1943. Twenty three years later, Egyptian scientist Abd el-Mohsen Bakir published it as the Cairo Calendar No. 86637.

The document is divided into three sections (Books I, II and III). Its largest part, Book II, consists of 365 passages, one for each day of the 360-day Egyptian year plus five epagomenal days. The passages seem to concern religious feasts, mythological incidents, favorable or adverse days, forecasts, and warnings.

University of Helsinki researchers Lauri Jetsu and Sebastian Porceddu have now performed a statistical analysis of the texts of this document.

“Our statistical analysis leads us to argue that the mythological texts of the Cairo Calendar contain astrophysical information about Algol,” the scientists said.

The analysis revealed that the periods of the variable star Algol (2.85 days) and the Moon (29.6 days) strongly regulate the actions of deities in this calendar.

Ancient Egypt City Aligned With Sun on King's Birthday

by Stephanie Pappas

The Egyptian city of Alexandria, home to one of the seven wonders of the ancient world, may have been built to align with the rising sun on the day of Alexander the Great's birth, a new study finds.

The Macedonian king, who commanded an empire that stretched from Greece to Egypt to the Indus River in what is now India, founded the city of Alexandria in 331 B.C. The town would later become hugely prosperous, home to Cleopatra, the magnificent Royal Library of Alexandria and the 450-foot-tall (140 meters) Lighthouse of Alexandria, one of the wonders of the ancient world. Today, more than 4 million people live in modern Alexandria.

Ancient Alexandria was planned around a main east-west thoroughfare called Canopic Road, said Giulio Magli, an archaeoastronomer at the Politecnico of Milan. A study of the ancient route reveals it is not laid out according to topography; for example, it doesn't run quite parallel to the coastline. But on the birthday of Alexander the Great, the rising sun of the fourth century rose "in almost perfect alignment with the road," Magli said.

The results, he added, could help researchers in the hunt for the elusive tomb of Alexander. Ancient texts hold that the king's body was placed in a gold casket in a gold sarcophagus, later replaced with glass. The tomb, located somewhere in Alexandria, has been lost for nearly 2,000 years.

Ancient Egyptians Recorded Algol's Variable Magnitude 3000 Years Before Western Astronomers

A statistical analysis of a 3000-year old calendar reveals that astronomers in ancient Egypt must have known the period of the eclipsing binary Algol

The Ancient Egyptians were meticulous astronomers and recorded the passage of the heavens in extraordinary detail. The goal was to mark the passage of time and  to understand the will of the Gods who kept the celestial machinery at work. 

Egyptian astronomers used what they learnt to make predictions about the future. They drew these up in the form of calendars showing lucky and unlucky days. 

The predictions were amazingly precise. Each day was divided into three or more segments, each of which was given a rating lying somewhere in the range from very favourable to highly adverse.

One of the best preserved of these papyrus documents is called the Cairo Calendar. Although the papyrus is badly damaged in places, scholars have been able to extract a complete list of ratings for days throughout an entire year somewhere around 1200 BC.

An interesting question is how the scribes arrived at their ratings. So various groups have studied the patterns that crop up in the predictions. Today, Lauri Jetsu and buddies at the University of Helsinki in Finland reveal the results of their detailed statistical analysis of the Cairo Calendar. Their conclusion is extraordinary.