The twin central pillars of Göbekli Tepe's Enclosure D.



Andrew COLLINS(1) and Rodney HALE(2)

Abstract: Göbekli Tepe consists of a series of stone enclosures built during the Early Holocene on an isolated mountaintop plateau in southeast Anatolia (Turkish Asia Minor). Speculation has mounted regarding the possible orientation of these monuments with respect to stellar targets, with the rising of Sirius (a CMa A) being proposed as the primary focus of three key monuments-Enclosures B, C & D. The authors demonstrate that such a conclusion is thwart with problems, due to Sirius's faint appearance and unsuitability as a stellar marker during the epoch of construction at Göbekli Tepe.

Key words: Göbekli Tepe, Giulio Magli, archaeoastronomy, Sirius, Orion, Cygnus, atmospheric extinction, aerosols, diurnal arcs, Pre-Pottery Neolithic, Deneb.

1. Author of From the Ashes of Angels (1996), The Cygnus Mystery (2006) and Göbekli Tepe: Genesis of the Gods (2014). 2. Chartered engineer MIET.

Göbekli Tepe is perhaps the most enigmatic discovery in archaeology for a long time-a series of megalithic structures constructed primarily by a hunter-gatherer society who thrived in the northernmost extension of the Fertile Crescent in the Early Holocene. The stone structures are located in a layered occupational mound (Arabic tell, Turkish tepe) situated at a height of approximately 780 m above sea level on an isolated mountain ridge at the western termination of the Ante-Taurus range (37°13'24.18" N, 38°55'20.85"E), some 15 km northeast of the city of Sanliurfa in southeast Anatolia.

Excavations under the auspice of the German Archaeological Institute (DAI) and Museum of Sanliurfa, and headed by Professor Klaus Schmidt of the University of Heidelberg, have taken place since 1995 and are ongoing today (see Schmidt 2012). An estimated ten percent of the tell has now been investigated, with four main enclosures and a large number of other structures being revealed.

Two types of structure are seen, one evolving from the other. The earliest enclosures, built c. 9500-8500 BC (Layer III, which corresponds to the Pre-Pottery Neolithic period-PPNA), originally incorporated twin monoliths with T-shaped terminations set up parallel to each other (see Fig. 1). Around them are in situ circles, or more correctly ellipses, of slightly smaller, standing stones (1.5-3 m in size), which are generally T-shaped in appearance and decorated with carved art showing zoomorphic forms and/or anthropomorphic features. These are arranged in a starburst fashion, their front narrow faces turned towards the center of the enclosure. They are set in stonewalls, which often incorporate stone benches (see Fig. 2).

Later structures, built c. 8500-8000 BC (Layer II, which corresponds to the Pre-Pottery Neolithic period-PPNB) are rectilinear in form and much smaller in size. They also contain T-shaped pillars, although here the stones, some of which are decorated, are reduced in size to no more than 1-1.5 m.

No evidence of domestic activity has been found at Göbekli Tepe, leading to speculation that it functioned as a regional centre of cultic activities during the tenth and ninth millennium. Its final sanctuaries were decommissioned and buried beneath the artificial mound around c. 8200-8000 BC (Schmidt, 2012).

Fig. 1. Enclosure C showing standing pillars in the perimeter wall.

Astronomical Targets

Even though the different forms of enclosure present at Göbekli Tepe prevents a single solution as to their overall function, the parallel alignment of the twin central monoliths has naturally prompted speculation regarding their possible alignment towards celestial objects, with Orion being proposed as a possible stellar target (Schoch, 2013) and also Cygnus (Collins, 2013a, 2013b, Collins & Hale, 2013). It is a line of enquiry worth pursuing, especially as the mountaintop plateau on which the occupational mound is situated would have had uninterrupted views of the local horizon.

Italian archaeoastronomer Giulio Magli dismisses Orion as being the target of the monuments at Göbekli Tepe as it would mean a much younger date for their construction, i.e. c. 8500-8000 BC, which does not match radiocarbon dating (see below). He dismisses also alignments towards Cygnus, which although correct, seem unnatural to what he sees as the natural orientation of the monuments towards the southeast. Instead, he proposes that the mean azimuths of twin central pillars in three key enclosures from Layer III-B, C, and D (see Fig. 2)-targeted the rising of Sirius between the dates 9100-8300 BC (Magli, 2013).

Magli points out that around 9300 BC Sirius began appearing low on the south horizon having been invisible from the latitude of Göbekli Tepe since c. 15,000 BC. The sight of this new "guest" star he suggests perhaps motivated the Proto-Neolithic communities of southeast Turkey to create the monuments of Göbekli Tepe.

Atmospheric Extinction

It is an intriguing theory, yet one thwart with problems from the outset. The biggest drawback with Sirius's use as a stellar target so soon after its reappearance is that it would have been barely visible to the naked eye, its usual bright magnitude diminished due to atmospheric extinction. This can be calculated using available mathematical formulae regarding the various sources of dimming affecting the apparent brightness of a star-see Schaefer (1993), with a further expansion by Flanders & Creed (2008). Using these formulae we can arrive at a measure of the likely magnitude loss, and therefore the visibility, of a star at any altitude above the horizon at the location of Gobekli Tepe. To achieve this, we must take into account a particularly variable component of the losses involving atmospheric aerosols, such as smoke, dust, moisture, etc, so we use a value representative of what is considered good viewing conditions. A widely accepted figure for the lower limit of human vision of a star is magnitude 6. Yet Schaefer, with good reason, finds that this figure should be magnitude 5.8, therefore we have adopted this value for the point at which a star is just visible.

Fig. 2. Plan of the main enclosures uncovered in the southeast section of Göbekli Tepe occupational mound.

Using these methods, we arrive at a mean value for the altitude at which Sirius becomes visible, which is 0.6°. Thus Sirius would not have been reliably visible at 0.5° altitude, the figure used by Magli to make his calculations. Having said this, there would undoubtedly have been occasions of better visibility when Sirius could have been dimly observed at this lower altitude. Yet this rather uncertain situation is enough on its own to make Sirius an unsuitable object for orientating such a major building project.
Diurnal arcs

Other factors also have to be considered regarding the observation of Sirius during the Early Holocene. The daily rotation of the Earth causes the stars to progress across the sky. In the case of Sirius, c. 9300-9000 BC, the star skims the southern horizon during its nightly transit. Yet as it becomes visible to the naked eye we find that for an increase of altitude above the horizon of half a degree, which occurs across a period of just 20 minutes, the star swings clockwise towards the south by no less than 3°.

So to use Sirius at an altitude of 0.5° to establish an accurate point of orientation, great precision would have been required to determine the presence of the star where it might or might not have become visible to the naked eye, a factor dependent on the atmospheric conditions existing at the time.

Fig. 3. Azimuths against the rising of Sirius at an altitude of
0.5 ° for the epoch 9500-8000 BC.
Mean Azimuths of Twin Central Pillars

Compounding the issues still further are inconsistencies in Magli's calculations of the mean azimuths of the twin central pillars of the monuments in question. His mean azimuths for the twin central pillars of the enclosures, and the dates they target the rising of Sirius at 0.5°, are given as follows:

Enclosure D 172° 9100 BC
Enclosure C 165° 8750 BC
Enclosure B 159° 8300 BC

For some reason, Magli's mean azimuths for two enclosures-B & D-differ from those suggested by the DAI's own site plan. Moreover, our own calculations suggest additional dating differences to those offered by Magli.

When these factors are taken into account, a slightly altered set of figures is achieved using the mean azimuths of the twin central pillars to determine their date of alignment towards the rising of Sirius at a height of 0.5° (and see Fig. 3):

Enclosure D 173° 9400 BC
Enclosure C 165° 8950 BC
Enclosure B 157° 8275 BC

In all instances the correlation date between Sirius rising and the alignment of the pillars has now altered slightly. For instance, in 9400 BC when the twin pillars of Enclosure D targeted the rising of Sirius, the star was barely visible to the naked eye across its entire transit of the southern horizon (see Fig. 4).

By 8950 BC when Enclosure C's twin pillars targeted the rising of Sirius, the star would still have been faint as it transited the meridian, due south.

Around 8275 BC, when the twin central pillars of Enclosure B targeted the rising of Sirius, the star climbed to make a more appreciable arc, reaching a maximum elevation of 6° as it crossed the meridian. Despite this encouraging fact, we now come into massive dating issues.
Bone samples taken from Enclosure B have provided radiocarbon dates in the range of 8306-8236 BC (Schmidt and Dietrich, 2010), coincident to the proposed date that its twin central pillars targeted the rising of Sirius. Yet according to the excavators these human remains probably come from intrusive burials made long after the structure's construction (Schmidt and Dietrich, 2010).

Fig. 4. Sirius's transit of the horizon at 9400 BC and 8950 BC showing its brightness relative to other key stars of the southern sky (Rodney Hale/Stellarium).

Indeed, Enclosure B is built on the plateau's bedrock immediately south of Enclosure D, and west of Enclosure C, which are both thought to have been in place by around 9000 BC (Schmidt & Dietrich, 2010). Thus there is every possibility that all three of these structures, along with Enclosure A, which lies immediately south of Enclosure B, are roughly contemporaneous. If so, then the twin central pillars of Enclosure B cannot have targeted the rising of Sirius at the time of their erection.


Taking all the evidence into consideration, Sirius's feeble appearance and unsuitability as a stellar marker during the epoch of construction at Göbekli Tepe makes it unlikely that the star's reappearance motivated the region's hunter-gathering society to give up its old lifestyle to construct the first monumental architecture in human history. For all these reasons the authors reject the proposal that the twin central pillars in Enclosures B, C & D at Göbekli Tepe were erected to target the rising of Sirius. They also reject the idea that its enclosures were oriented towards the southern horizon. Instead, they propose that the true orientation of the monuments was north, towards the polar region, where the mean azimuths of two key enclosures-C & D-target the setting of Deneb (a Cygni), the brightest star in the constellation of Cygnus, in the epoch c. 9400-8900 BC (see Collins, 2013a, 2013b, and Collins & Hale, 2013).


Collins, Andrew, "Göbekli Tepe: Its Cosmic Blueprint Revealed", 2013a,
Collins, Andrew, "Göbekli Tepe and the Worship of the Stars",
Collins, Andrew, and Rodney Hale, "Göbekli Tepe and the Rebirth of Sirius", 2013,
Flanders, Tony, and Phillip J, Creed, "Transparency and Atmospheric Extinction" Sky and Telescope, 10 June 2008 (October 2013 reprint),
Magli, Giulio, "Possible astronomical references in the project of the megalithic enclosures of Göbekli Tepe", [physics.hist-ph]
Schaefer, Bradley, Universities Space Research Association, "Astronomy and the Limits of Vision", Vistas in Astronomy 36 (1993), pp. 311-361
Schoch, Robert, Forgotten Civilization: The Role of Solar Outbursts in Our Past and Future, Inner Traditions, Rochester, VM, 2012
Schmidt, Klaus, Göbekli Tepe: A Stone Age Sanctuary in South-East Anatolia, ex oriente e.V., Berlin, 2012
Schmidt, Klaus, and Oliver Dietrich, "A Radiocarbon Date from the Wall Plaster of Enclosure D of Göbekli Tepe" Neo-Lithics 2/10 (2010), 82-83

öbekli Tepe: Genesis of the Gods
Published by Bear and Company, Rochester, VM