Space Science in Ancient Egypt


Ancient Egypt intrigues general audiences. Its pyramids, Sphinx, and complex supernatural belief system have often attracted the attention of pseudoscience. Erich von Daniken’s popular and controversial book Chariots of Gods, for instance, speculated that extraterrestrials influenced ancient Egypt’s religion and civilization.

Entertaining as such conjecture may be, scientists provide us with sounder explanations of ancient Egypt, including of its astronomical traditions. They have explained, for instance, why the Great Pyramid is more accurately aligned to True North than the Greenwich Observatory’s Meridian Building: builders aligned pyramids by observing two circumpolar stars.

The Ancient Egyptians wrote Calendars of Lucky and Unlucky Days that assigned astronomically influenced prognoses for each day of the year. Lauri Jetsu and Sebastian Porceddu discover the actual rules in the appearance and behavior of deities during the whole year.

Filling Space spoke with Mr. Sebastian Porceddu of Helsinki University, who has studied ancient Egyptian calendars about luck associated with certain days of the year. One calendar in particular, the so-called Cairo Calendar, has been a focus of his research. Dr. Porceddu spoke with Filling Space about his experience with ancient Egyptian astronomy.


How did you end up studying so much ancient Egyptian astronomy?

Right away when I started my studies of astronomy in the University of Helsinki I had the idea to take a few courses on Egyptology or Assyriology because of my interest in these cultures. I was thinking of Egyptology as something like recreation, to relax the mind from the mathematical approach of astronomy with the ancient texts that had always fascinated me. Egyptologists in the university were a small and tight group so there was lots of support for me to continue the studies further on the side until I found myself doing two master’s degrees at the same time. At that point, it was natural to specialize in ancient astronomy. But it was almost by accident that we chose to analyze the Cairo Calendar, a choice that yielded surprising discoveries.

What modern relevance does understanding ancient Egyptian astronomy have?

Ancient Egyptian astronomy is in general more interesting to Egyptologists than it is to astronomers, even though it is a common subject in popular science and pseudoscience. In ancient cultures, a clear delineation between religion and science did not exist, so in general ancient astronomy yields very little astronomical data, though we were lucky to find data when studying the Cairo Calendar. Understanding the development of myths and observations is of course relevant for the philosophy of science because the ancient people were not that different from us – they had similar brains but not all the tools.

What is the most exciting thing you have found during your research that you would like other people to know?

My colleagues and I found recordings of the brightness variability of a star called Algol – thousands of years before modern astronomers first noted this variation. We are not the first to suggest ancient astronomers knew of this brightness variation, but using time series analysis we were able to calculate the period of variability from the Cairo Calendar. This provided a piece of astrophysical information from long before astrophysics existed. Throughout our research, it was also exciting to discover the belief system that motivated the observations. It was a world where scribes held the keys to both science and magic, where writing itself was considered powerful and dangerous.