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Astronomy and the Great Pyramid

J. Donald Fernie

Anatomy of a Pyramid

Whatever the excesses of its advocates, the Great Pyramid is one of the most remarkable structures ever made, if only in terms of sheer workmanship: The fact that it is the only standing remnant of the seven ancient wonders speaks for itself. Built roughly 4,500 years ago, it towers over the Giza plain some 16 kilometers west of Cairo amid several smaller pyramids, 60 or more of which stretch down the western bank of the Nile. The base of the Great Pyramid covers 13 acres, or about seven midtown blocks in Manhattan. It rises in 201 stepped tiers comprised of more than two million pieces of limestone and granite, averaging two or three tons apiece (with some a good deal more), to the height of a modern 40–story building. It was the tallest construction in the world until the Eiffel Tower was erected in the 19th century.

For the first 3,000 years or so of its history, the Great Pyramid was encased in brilliant polished limestone—about 22 acres of it. The slabs were up to 2.5 meters thick and were fitted together with joints so fine they could scarcely be seen, according to Herodotus, who visited in 440 B.C. This must have been a dazzling sight in the Egyptian sun! Unfortunately, the covering was stripped in medieval times to build palaces and mosques in Cairo, and now we can only see the rough building blocks.

Under this shining canopy lay the interior structure. Strabo, after a visit in 24 B.C., described an entrance on the north face of the pyramid made of a hinged stone that could be raised but was otherwise indistinguishable from the stones around it. So indistinguishable, in fact, that its location was lost during a period of neglect in early Christian times. Much later, in the early 9th century, an Arab potentate named Al–Mamun, following rumors of vast, hidden wealth, forced a new entrance near the base of the north side. So impregnable was the structure that his engineers could proceed only by building fires against each huge stone in their path and, having heated it to a high temperature, dousing it with cold vinegar to shatter it. The residue was cleared, and they repeated the process on the next stone. Inching forward in this way for some 30 meters, and almost at the point of giving up, they broke through into a pre–existing tunnel, later termed the Descending Passage because it started high on the north face and sloped smoothly into the pyramid's depths below ground level. Unlike the ragged tunnel gouged by Al–Mamun's men, the Descending Passage, about a meter square, was astonishingly straight. It was so exact that in 1881, Flinders Petrie, an experienced, professional surveyor and skeptic, using the best equipment then available, found that the average departure from a perfect line over the full length of some 100 meters was less than 7 millimeters.

Of less interest was the discovery of another tunnel, the so–called Ascending Passage, which led off of the Descending Passage and headed up to what the potentate's henchmen called the King's Chamber because it had a flat ceiling, which was an Arab custom for male deceased. An offshoot of the Ascending Passage led to the Queen's Chamber, so called for its gabled ceiling. The dimensions of these rooms, along with the overall dimensions of the pyramid itself, provoked endless discussion among luminaries such as Isaac Newton and John Herschel, who speculated that the measurements might hold the key to converting biblical units to their modern equivalents. Although this numerical Rosetta Stone never emerged, Newton did conclude that the builders must have employed more than one unit of length.

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