Newsgroup: it.discussioni.misteri
Titolo: [Bauval] smontato dal Prof. A.P. Fairall

http://users.iafrica.com/m/mi/mikeyb/Orion_Fairall.html
Precession and the layout of the Ancient Egyptian pyramids
by
Prof. A. P. Fairall
Dept of Astronomy, University of Cape Town
Planetarium of the South African Museum.
Many members of the public have been captivated by recent
books and video presentations concerning the pyramids and
the sphinx of ancient Egypt. The books by Graham Hancock,
Robert Bauval and Adrian Gilbert make the rather astounding
proposal that the layout of the site at Giza goes back to
10500 BC. In archaeological terms, it is somewhat
preposterous, to say the least. But the basis for fixing
that date lies in astronomy. Bauval, in particular, explains
the workings of precession, and sees it as the key to fixing
the time of the layout back in the distant past.
The topic is one well suited to a planetarium. Based on
lectures that I had given to our local Egyptian Society in
the planetarium in Cape Town, I designed and scripted a
prerecorded presentation (that opened in December 1998). I
had found the Bauval argument ingenious, but somewhat
unconvincing. However, further checks revealed further
holes, as I shall report below.
The pyramids have a strong astronomical association. The
four faces of an Egyptian pyramid are precisely aligned with
the four cardinal points of the compass. Given that the
Egyptians never recognised a North pole on the Earth, they
could have only done this by means of the rotation of the
sky about the North Celestial Pole. The most obvious way of
fixing azimuthal North would be by the symmetry of the
rising and setting points of stars. The great pyramid of
Khufu is level to a centimetre and aligned to a twentieth of
a degree, a tribute to the accuracy of ancient surveying
skills.
Khufu's pyramid also contains four "star shafts", aimed
towards the meridian in the sky. When the pyramid was built
(c. 2500 BC), these shafts aimed at the transitpoints of
Thuban (Alpha Draconis - then pole star), Orion's Belt,
Sirius and Kochab (Beta Ursa Minoris), clearly intentionally
and not coincidentally. The shafts apparently served to
direct the ka, or spirit, of the dead pharaoh towards these
key stars. Thuban and Kochab were circumpolar "Imperishable
ones" (stars that never die), Orion represented the deity
Osiris, and Sirius his consort, Isis. Precession has since
changed the transit points, so the shafts no longer function
in this manner.
Khufu's pyramid is the largest of a line of three - together
with that of Khafre and the much smaller pyramid of
Menkaure. Given the surveying skills of the Egyptians, many
have wondered why the line of the three pyramids is slightly
crooked. One possibility is that the design would allow for
the smaller pyramid to be later enlarged (retaining its
south and east faces) to form a straight line of three
almost identical pyramids. Another is that the deviation of
the line closely matches that of the three stars of Orion's
Belt - which are also slightly crooked. This has suggested
that the lay out at Giza may be an attempt to portray
Orion's Belt. If so, the orientation of the line, with
respect to the cardinal points, is wrong - for 2500 BC.
Precession, however, changes the angle that the Belt makes
in the sky. Bauval claims that going back to 10500 BC gives
"a perfect match".
Or does it? My own investigation showed that, while the line
of the two outer pyramids is set 38 degrees from north, the
angle of Orion's Belt to north in 10500 BC is close on 50
degrees! Hardy an exact match. I calculate that circular
precessional motion would give 47 degrees, whereas including
nutational terms makes it slightly higher. Measurements in
the planetarium agree. Bauval, on the other hand appears to
have used computer programmes. He implies that only with
modern sophisticated computers can we examine the ancient
skies! I wonder if he also made the mistake of measuring
angles off a flat screen.
Bauval's choice of 10500 BC (when Orion is furthest south in
its precessional cycle) also supposedly fits with the Milky
Way aligning with the Nile. But the course of the Nile is
variable, and we do not now know where it ran in 10500 BC
with any accuracy.
A parallel assertion of Hancock and Bauval is to say that
10500 BC would be during the astrological "Age of the
Lion" - a connoctation they seek with the sphinx. However
the Vernal Equinox of 10500 BC would lie at 2000: 11h40m,
+2.2 degress, which though close to the star pattern we now
know as Leo, still lies decidedly in Virgo. Again, not a
perfect match.
Finally, as my colleague in the planetarium world, Ed Krupp,
has pointed out, the otherwise straight line of the pyramids
is deformed towards the north, but the line of Orion's Belt
is deformed towards the south.
The astronomical basis for arguing that the layout at Giza
goes back to 10500BC is therefore very thin. It would be
well if more could be done to counter the publicity of
books, put out to the public, that base so much conjecture
upon such flimsy science.
Anthony Fairall,
Dept of Astronomy, University of Cape Town,
Rondebosch, South Africa, 7700.
-------
References
Bauval R. & Hancock G. 1996, Keeper of Genesis, Mandarin
(London).
Fairall A. P. 1998, The Astronomy of the Great Pyramid,
Planetarium presentation, South African Museum, Cape Town.
Krupp E. 1997, Sky & Telescope, 93, 2-64.
Back to Early Ancient Egyptian History

 Planetarium of the South African Museum.
[maxi cut]
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dell'erosione pluviale della Sfinge (o del Leone?)...
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angles off a flat screen.
eh? ma lha mai usato un programma come skyglobe questo qua?? :)
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