Stars Reveal Age of the Pyramids

Nov. 15 -- Just how old are the pyramids? The answer may lie in the stars.

Current estimates for the construction of the pyramids, based onsurviving lists of the pharaohs, are believed to be accurate towithin about 100 years.

But Cambridge University Egyptologist Kate Spence says that byanalyzing the relative position of Earth and two stars, she hasdated the construction of the Great Pyramid at Giza — one of theSeven Wonders of the Ancient World — to within five years of 2478B.C.

That means the Great Pyramid is 4,478 years old — or 75 yearsolder than one commonly accepted estimate.

Arranged by the Stars

Her estimate comes from her proposed solution to anothermystery: How did the ancient Egyptians align their pyramids so thattwo sides ran so precisely north-south?

She suggests that they used a pair of stars found in the Littleand Big Dippers.

But because Earth wobbles on its axis, those two stars wouldhave given different indications for “north” over the centuries.So by calculating when that pair of stars would have been in anorthern alignment, Spence says she can figure out when thepyramids were built.

In Thursday’s issue of the journal Nature, Spence says thetwo-star method could explain the various degrees of inaccuracy inthe orientation of pyramids built at different times.

Today’s north star, Polaris, was in the wrong position in thosedays to help the pyramid builders. Spence instead employs the starsMizar, found in the Big Dipper’s handle, and Kochab, in the bowl ofthe Little Dipper.

When the pyramids were built, these stars circled nightly arounda point over the North Pole. So, when one star appeared directlyover the other, the Egyptians could have used a plumb line to findnorth, Spence says.

Pointing North

It’s not clear whether the Egyptians really did that, but “thetechnique she argues for seems very reasonable” and deservesfurther study, says Edwin Krupp, director of the GriffithObservatory in Los Angeles. The paper could provide “severalpieces of a very intriguing puzzle.”