Pyramid alignment to north

How straight is straight

The builders of the 4th Dynasty set out the great pyramids so that their sides face north, south, east and west with errors far smaller than a degree. The Great Pyramid of Khufu is the most accurate. Kemet had no magnetic compass, and true north is not marked by any bright star today, so this accuracy needed careful observation of the sky. That the pyramids are aligned this precisely is Documented. How the builders did it is Debated, and several named scholars have put forward methods.

The star method (Spence)

In 2000 the Egyptologist Kate Spence of the University of Cambridge proposed in Nature that the builders hung a plumb line and waited until two stars on opposite sides of the celestial pole, Kochab in the Little Dipper and Mizar in the Big Dipper, lined up vertically. At that moment the line points to true north. Because the slow wobble of Earth's axis (precession) moves the stars over centuries, this method would have drifted slightly from one generation to the next. Spence found that the small errors in a series of pyramids follow such a drift, and she used it to date the start of the Great Pyramid to about 2480 BCE, roughly 80 years later than many chronologies.

Critics replied that her drift rate contained a mathematical error. When corrected, they argued, it points to a different pair of stars and does not require shortening the chronology. The astronomer Juan Antonio Belmonte of the Instituto de Astrofísica de Canarias proposed instead that the builders watched the stars Phecda and Megrez, which would fit a date around 2562 BCE (IAC).

The sun method (Dash)

The engineer Glen Dash proposed a simpler method in 2017. On the autumn equinox, the tip of a shadow cast by a vertical rod traces an almost straight east–west line across the day. Dash tested this at his home in Connecticut, and the small counter-clockwise error he got resembles the error found in the Great Pyramid, Khafre's pyramid and the Red Pyramid. He suggests the builders could have found the equinox by counting days from the summer solstice. Dash himself notes that no direct evidence shows the method was used.

Where this leaves us

Every proposed method works in principle, and none is confirmed by an ancient text. What is clear is that Kemetic surveyors combined astronomy, geometry and patient fieldwork to set out monuments of a size and accuracy unmatched for thousands of years. The claim that the Giza pyramids were laid out as a map of the stars of Orion is a separate idea, examined in Esoteric Studies under The Orion correlation theory.