Egyptian astrologers discovered change star

Scarred description of the change of light from the changeable star Algol already 3, 200 years ago

Was the god Horus in the ancient Egyptian Cairo calendar for the variable star Algol? © public domain
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Astronomical know-how under pyramids: Even the ancient Egyptians could have discovered the variable star Algol and used for calendar calculations. For the change in brightness of this star, which is visible to the naked eye, is represented by the god Horus in the more than 3, 000-year-old Cairo calendar, as Finnish researchers have found out in analyzes of the text. Whenever the star was particularly bright, Horus appeared and made it a good omen.

Astronomy is not an invention of modern times - on the contrary: Millennia before the invention of the telescope, people observed the movements of the moon and the sun and even set up observatories. Particularly advanced were the cultures of the Orient, as evidenced not least by the biblical "three wise men from the East" who followed a celestial event as far as Bethlehem.

Is the Cairo calendar astronomical?

But also in Egypt people started to run calendars and to divide times according to celestial events. The so-called Cairo calendar from the period 1244 to 1163 BC testifies to this. In it the Egyptians listed which days promised their prognosis for luck or misfortune. This is circumscribed about mythological figures, for example: "Horus jubilee. Feast of the entry of heaven and the two benches. "Or" The day on which Horus gives the white crown. "

Extract from the approximately 3, 200-year-old Cairo calendar, framed is the term "Horus" © Lauri Jetsu

"So far, there was only speculation that many of these mythological texts in the Cairo calendar based on astronomical phenomena, " explains Sebastian Porceddu from the University of Helsinki. To clarify matters, he and his colleague Lauri Jetsu analyzed certain words and their assignment to days in the calendar and checked which celestial events they might coincide with.

A changeable star

The result was surprising in several ways. Because the Egyptians not only aligned their calendars with the moon and its phases and movements, but apparently also after a star: the changeable star Algol in the constellation Perseus. It changes its brightness at a regular rhythm of 2.85 days, because a larger, darker star in this system precedes a small, very bright one and dims its light slightly. display

The star Algol changes its brightness periodically, as a darker star passes in front of a lighter star partner. Fabien Baron, University of Michigan / CC-by-sa 3.0

This change in brightness can already be seen with the naked eye. It is therefore not surprising that a description of this star already appears in the Arab astronomers of the Middle Ages. They gave him his name: "Algol" comes from the Arabic "Ras al-Gul" and means as many as "head of the D mons".

God Horus as a star representative

But as it turns out, the ancient Egyptians may already have discovered and observed this changeable star. For in their calendars cycles of 2.85 days often appear - exactly the time that Algol needs for one cycle of its brightness fluctuation. "Algol was represented in the calendar by Horus, " Porceddu and Jetsu conclude from their analyzes. The god Horus symbolized divinity and dominion.

"The lyrics describing Horus's actions are in keeping with what an observer would have seen with his naked eye on Star Algol, " the researchers say. The particularly bright phases of Algol were attributed positive days in the calendar. "This supports our thesis that the Cairo calendar is the oldest historical testimony to such a changeable star." Incidentally, the moon also appears in the G tter shape on the Cairo calendar: He is represented by the patron deity Seth.

Discovery nearly 3, 000 years earlier

"We are sure that the actions of the gods described in the Cairo calendar over the course of the year are linked to the regular changes of Algol and the Moon, " says Porceddu. "In contrast to previous attempts, we have uncovered the rules behind the appearance and behavior of these gods."

Should this be confirmed, the discovery of the star Algol and its change of light must be postponed by three millennia into the past. In the Middle Ages, as early as 1200 BC, scholars in ancient Egypt observed this changeable star. (PLOS ONE, 2015; doi: 10.1371 / journal.pone.014414)

(University of Helsinki, 30.12.2015 - NPO)