- New Theory On Pyramid Alignment
- By Robert C. Cowen
- Special to The Christian Science Monitor
- British archaeologist Kate Spence has a novel
solution to an Egyptian mystery. It explains how ancient surveyors
could have used stars to orient the pyramids at Giza when they had no
pole star to guide them. It reduces the uncertainty in the start date
for Great Pyramid construction from a century to a mere 5 years.
- While the Giza pyramids have not been accurately
dated before, investigators have marveled at the accuracy with which
they are aligned to the compass' cardinal points. The western and
eastern sides of the Great Pyramid, in particular, align with true
north to within 3 arcminutes - about a tenth the width of the full
- No one has explained such surveying skill
satisfactorily. Polaris had not yet taken up its position as our North
Star guide. Now Dr. Spence at the University of Cambridge in England
has found two other stars on either side of the pole that, taken
together, do the job.
- One - Mizar - is in the middle of the Big Dipper's
handle. The other - Kochab - is in the Little Dipper's bowl. Twice a
day these stars line up vertically - each lying about 10 degrees from
north. An imaginary line between them passes near the celestial north
pole. That line ran very close to the pole at the time of Egypt's Old
kingdom when the Giza pyramids were built 4,400 to 4,600 years ago. It
actually ran through the pole in 2467 BC.
- To find north, a surveyor had only to wait until the
daily rotation of the heavens brought that stellar lineup into
coincidence with a vertical plumb line on Earth.
- Spence notes that the Great Pyramid is the most
accurately aligned of the Giza group. She also notes that the stellar
lineup gave the most accurate northerly direction in 2467 BC.
Therefore she picks that date with an uncertainty of 5 years due to
pyramid measurement errors as the date for the start of the pyramid's
- Previous dating based on tracing the lengths of the
reign of successive kings dated construction to that general period
but couldn't come closer than 100 years. Radio carbon dating couldn't
do any better.
- Harvard University science historian Owen Gingerich
calls Spence's theory "the most interesting idea to come down the
pike in a long time for aligning the pyramids."
- A century or more of attempts to explain the
alignments astronomically had been disappointing. Dr. Gingerich says
that he was ready to dismiss this latest effort out of hand when the
journal Nature, which published Spence's account Nov. 16, sent it to
him for comment. But he adds that, as soon as he read it, he realized
"this is a very serious paper."
- He notes that one of its most persuasive aspects is
the way Spence's theory neatly accounts for the history of small
deviations from true north in the pyramids' construction.
- Beginning with the earliest pyramid, surveyor's
errors become progressively smaller until they reach a minimum with
the Great Pyramid. After that time, they became successively larger.
This history correlates with the way the Kochab-Mizar lineup first
comes closer to true north and then moves away due to the wobbling of
- The axis traces a circle on the sky every 26,000
years. This changes the positions of stars as seen from Earth. Ancient
Egyptians would not have noticed this unless they kept systematic
astronomical records for which there is no evidence.
- Meanwhile, Spence says there's more research to be
done. She calls the ability to fix the pyramid dates "an advance
in establishing a reliable absolute chronology for the second half of
the third millennium BC." But, she adds, "it does not solve
all the problems." This dating has to be fitted into the full