cairo calendar
A page of the Cairo Calendar with the hieratic writing for the word 'Horus' in the superimposed rectangleLauri Jetsu

The Ancient Egyptians linked the changes of Algol and the Moon to their deities in their calendar, a new study has revealed. Algol, the variable star which reaches its brightest point every 2.85 days, and the moon, which appears full every 29.6 days, are heavily connected to the actions of the Gods in the Cairo Calendar.

The theory that the ancient Egyptians took astronomical cycles into account in their calendar has long been thought to be true, but the research carried out at the University of Helsinki proves that it is indeed true. This also means that the first variable star – in the form of Algol and its period were discovered almost 3,000 years before Geminiano Montanari first 'discovered' it in 1667 – were included in the Egyptian's calendar between 1244BC and 1163BC.

The research, which was published in PLOS One, also confirms that the moon and Algol had positive connotations for the Ancient Egyptians. However, the researchers say that there will continue to be sceptics who refuse to believe how far ahead of the times the ancient Egyptians were.

Lauri Jetsu from the Department of Physics at the University of Helsinki said: "I would have serious doubts, if someone claimed, for example, that the Bible contains information about water in Mars. We claimed that Ancient Egyptian religious texts contain astrophysical information about Algol. It was no surprise to us that there were, and there still are, sceptics."