Egyptian papyrus turned out to be a precise description of a mysterious star.

An international team of scientists found that the Egyptian papyrus, known as the Cairo calendar, may be the oldest written evidence of observations of the varying brightness of the star Algol.

The study is published in the journal Open Astronomy, and briefly about it tells Phys.org. This is an ancient papyrus, which for many years was considered the calendar of happy and unlucky days. It dates from 1244-1763. BC. The calendar gives predictions for each day of the Egyptian year.

However, as early as 2012, astronomers from the University of Helsinki (Finland) noticed that the calendar also contains information about astronomical observations. In particular, the behavior of the unusual Algol triple system is described.

The star observed from the Earth is flickering: over time it becomes brighter and dimmer. European astronomers noticed this in 1667. Only in 1881 the second star of this system was discovered, and information about the third appeared relatively recently.

A new study showed that the ancient Egyptians accurately described the Algol phenomenon 3,000 years before the official discovery of this star. They used myths about the gods Horus and Seth. The study presents ten arguments that prove that unknown authors wrote down accurate data on Algol in the Cairo calendar.

“The discovery of the variable brightness of Algol should have been dated thousands of years earlier than previously thought,” said study co-author Sebastian Porssed of the University of Helsinki. “This star was part of ancient Egyptian mythology as a form of worship for the god Horus.”