Ancient Time Keepers, Part 3: Archaeoastronomy

Part 3: Archaeoastronomy

Archaeoastronomy is the study of how people in the ancient past have understood and used the phenomena in the sky, and what role the sky played in their cultures.

Ancient monuments and writings from around the world are undeniable proof that thousands of years ago people had advanced astronomical knowledge. We propose that in fact all ancient sites of any major significance were constructed in order to allow astronomical observations and time tracking – and often, as the record/expression of their knowledge.

  In this article we explore connections of famous ancient sites to astronomy (Note:  In Part 4 we explain ancient calendars and units of measure.)

Sun-god Viracocha from the Gate of the Sun (Puerta del Sol), Tiwanacu. The frieze on the gate serves as a calendar and provides “instructions” how to use 11 pillars on the nearby structure called the “calendar wall”.  Note: Viracocha, Kukulkan, and Quetzalcoatl were all the same individual.  His other names were, Gucumatz in Central America, Votan in Palenque and Zamna in Izamal.    As Viracocha he was teacher to the Incas.  As Kukulkan he taught the Maya everything from Astronomy to Irrigation.  “Quetzalcoatl” was his name to the Aztecs and he taught them as well.

Stonehenge – an ancient observatory (2900 BCE)

Seshat (left image above), Egyptian goddess of writing and wisdom and  Ibis depiction of Thoth (right) – god of magic, wisdom and writing

The Northern [Bottom] and Southern [Top] Panel ‘Decan Chart’ from the Tomb of Senmut [c 1500 BC]. [In reality this panel is about 4 m long.] The decan system was actually used as a clock for time keeping in the night hours and through the year – modern Egyptologists call them Egyptian sidereal clocks.


The heliocentric universe was known in antiquity

Thousands of years before Copernicus published De Revolutionibus Orbium Coelestium people considered the Sun as the center of our planetary system.

In De Revolutionibus Orbium Coelestium  (published 1543) Copernicus re-established the order of planets and proposed a heliostatic universe.
However he was not the first to propose it.

Aristarchus of Samos (ca. 310-230 BC) and others proposed that the sun was motionless in the center of an infinitely large sphere of fixed stars, and that the earth revolved about it, as well as rotating about its axis. The story is told in Sir Thomas Heath’s Greek Astronomy (1932, New York: Dover, republished 1991) and Aristarchus of Samos, the Greek Copernicus (1913). The lack of an adequate theory of motion and inertia as well as the position of the Church) caused the usual view of a fixed earth to prevail.

Aristarchus also estimated the distances of the sun and moon from the earth. The measurements were not accurate enough to give a correct result, but did show that the sun was much more distant than the moon. Eratosthenes, somewhat later, estimated the radius of the earth, obtaining a value that happened to be accurate, although his estimate was thought too large (which encouraged Columbus). These accomplishments are of the greatest significance, as we can see from our perspective. No other science or religion in history came within miles of a similar understanding.

Archimedes discusses Aristarchus in his Sand-Reckoner. A translation is: Aristarchus of Samos proposed certain hypotheses in writing, from which it followed that the universe was much larger than is now commonly believed. He proposed that the firmament and the sun were unmoving, and the earth described a circle about the sun, which was located at the centre of the orbit, and that the sphere of the fixed stars was as great relative to the orbit of the earth as a sphere is to its center.

Antikythera Mechanism is undeniable example of advanced astronomical knowledge possessed by astronomers thousands of years ago.

3.1 Astronomical Alignments of Ancient Monuments (Pyramids and Temples)

The evidence of  very good understanding by the ancient people of astronomical cycles of our planet can be found in their monuments (pyramids and temples) and  surviving written records (found in Mesoamerica, Egypt and India). Places like Stonehenge and Pyramids of Egypt and Mesoamerica reveal in their location, orientation, shape and dimensions incredible astronomical knowledge.

The easiest way to record spatial observations — other than by framing them against a prominent topographic features — was by erecting durable markers of their own in the landscape (including pyramids and temples)  to calibrate the rising or setting azimuths of the sun, moon, planets and stars.

Most of the ancient structures were used as astronomical markers/observatories and functioned as calendars. Below we are presenting just a few examples.

Nabta, Egypt

STANDING STONES at Nabta in the Nubian desert  predate Stonehenge and other astronomically aligned sites in Europe (site’s age estimate: between 6400 and 4900 BC)
They are the oldest dated astronomical alignment discovered so far and bear a striking resemblance to Stonehenge and other megalithic sites constructed a millennium later in England, Brittany, and Europe.

In Nabta, there are six megalithic alignments extending across the sediments of the playa, containing a total of 24 megaliths or megalithic scatters. Like the spokes on a wheel, each alignment radiates outward from the complex structure.

A stone circle at Nabta Playa in Egypt's Western Desert is thought to act as a calendar and was constructed around 7000 BC

Fig.1 Calendar Circle at Nabta

Fig.2 A line of megalith (ca 4,800 B.C.) which coincides with the rising position of Sirius
in Nabta during the summer solstice (image courtesy of M. Shaltout)

Fig. 3 In the Sahara Desert in Egypt lie the oldest known astronomically aligned stones in the world: Nabta. Over one thousand years before the creation of Stonehenge, people built a stone circle and other structures on the shoreline of a lake that has long since dried up. Over 6,000 years ago, stone slabs three meters high were dragged over a kilometer to create the site. Shown above is one of the stones that remains. Little is known about the ultimate purpose of Nabta and the nature of the people who built it. Photo credit: J. M. Malville (U. Colorado) & F. Wendorf (SMU) et al.  Source:

 These standing megaliths and ring of stones were erected from 6.700 to 7,000 years ago in the southern Sahara desert. Although more research needs to be done, many scientists, believe that the alignments had an astronomical significance.

Three hundred meters north of these alignments is the stone calendar circle. Compared to Stonehenge, this circle is very small, measuring roughly 4 m in diameter. The calendar consists of a number of stones, the main ones being four pairs of larger ones.

Fig. 4 & 5
The stone calendar circle near Nabta

Each of these four pairs were set close together to form “gates.” Two of these pairs align to form a line very close to a true north-south line, and the other two pairs or gates align to form an east-west line. The east-west alignment is calculated to be where the sun would have risen and set from the summer solstice 6,500 years ago (4,500BC).  


Stonehenge, England

Archaeologists suggest that the iconic stone monument was erected around 3000BC – 2500 BC. Many Stonehenge alignments exist which undoubtedly indicate the astronomical significance of Stonehenge’s construction. For  example, the axis of Stonehenge aligns approximately to the midsummer rising sun azimuth.

Stonehenge is a megalithic monument on the Salisbury Plain in Southern England, composed mainly of thirty upright stones (sarsens, each over ten feet tall and weighing 26 tons), aligned in a circle, with thirty lintels (6 tons each) perched horizontally atop the sarsens in a continuous circle. There is also an inner circle composed of similar stones, also constructed in post-and-lintel fashion.


Fig. 1                                                   Fig.1b

Fig. 1c The axis of Stonehenge aligns approximately
to the midsummer rising sun azimuth.

Fig. 3 Aerial View of Stonehenge


– – –

In the foregoing picture a line (blue) originating at Stonehenge’s centre, dissects the centre of the Heel stone. The azimuth angle of this line, off North, is 51.18333 degrees, which equates to 51 degrees, 11 minutes. This is the official latitude designation for Stonehenge (51 deg. 11 minutes).

Note how the line relates to the Avenue set of circles (magenta) and brushes the northern side of the large post marker adjacent to the Avenue circles. A nearby line of posts extends toward the Heel Stone, as if to indicate this “latitude” line.

It is normal carpentry or surveying practice to have “sighting-lines” run to the “side” of pegs or posts, rather than to the centres, as far greater accuracy is achieved and the surveyor is able to visually verify the accuracy of the full alignment. When a line runs to the centre of a stone, the stone itself will generally have a peaked or pointed top to finitely indicate the refined intended position of the alignment.

Another circle of immense importance, which links Stonehenge to the Lunar codes of the Khafre Pyramid of Egypt. It will be noted that this circle (2nd inward red) brushes two component positions on the Avenue, one of which has the official designation “B”. The diameter of this circle is 472.5 feet, which is exactly the intended vertical height of the Khafre Pyramid of Egypt. The base measurement of Khafre was 15/16ths that of the Great Pyramid or 708.75 feet. It was also built to a 3,4,5 triangulation code, with 1/2 the base length acting as the adjacent (354.375 feet), the vertical height acting as the opposite (472.5 feet) and the diagonal face acting as the hypotenuse (590.625 feet).

Each of these values was in deference to the lunar month and lunar year (based upon 29.53125 days per lunar month or 345.375 days per lunar year).

The diameter of this Stonehenge circle is, therefore, coding the height of the Khafre Pyramid in increments of 16 X 29.53125-days/ feet. This value of 472.5 days was also integral to the ancient method of measuring the 18.613-year lunar nutation cycle, which was calibrated to endure for 6804-days (230.4 lunar months of 29.53125-days or 14.4 time periods of 472.5-days duration). Note also that 230.4 is an expression of the very important ancient number 11.52.


Chankillo, Peru

Possibly the oldest solar observatory in the Americas has been found, suggesting the existence of early, sophisticated Sun cults, scientists report.

It comprises a group of 2,300-year-old structures, known as the Thirteen Towers, which are found in the Chankillo archaeological site, Peru. The towers span the annual rising and setting arcs of the Sun, providing a solar calendar to mark special dates. The study was published in the journal Science.

The Thirteen Towers constitute an ancient solar observatory

When viewed from the western observation point, the Sun appears to the left of the left-most tower

Clive Ruggles, professor of archaeoastronomy at Leicester University, UK, said: “These towers have been known to exist for a century or so. It seems extraordinary that nobody really recognised them for what they were for so long.

“I was gobsmacked when I saw them for the first time – the array of towers covers the entire solar arc.” The Thirteen Towers of Chankillo run from north to south along the ridge of a low hill within the site; they are relatively well-preserved and each has a pair of inset staircases leading to the summit.

The rectangular structures, between 75 and 125 square metres (807-1,345 sq ft) in size, are regularly spaced – forming a “toothed” horizon with narrow gaps at regular intervals.

About 230m (750ft) to the east and west are what scientists believe to be two observation points. From these vantages, the 300m- (1,000ft-) long spread of the towers along the horizon corresponds very closely to the rising and setting positions of the Sun over the year.

“For example,” said Professor Ruggles, “if you were stood at the western observing point, you would see the Sun coming up in the morning, but where it would appear along the span of towers would depend on the time of the year.”

“So, on the summer solstice, which is in December in Peru, you would see the Sun just to the right of the right-most tower; for the winter solstice, in June, you would see the Sun rise to the left of the left-most tower; and in-between, the Sun would move up and down the horizon.”

This means the ancient civilisation could have regulated a calendar, he said, by keeping track of the number of days it took for the Sun to move from tower to tower.

Sun cults

The site where the towers are based is about four square kilometres (1.5 square miles) in size, and is believed to be a ceremonial centre that was occupied in the 4th Century BC. It is based at the coast of Peru in the Casma-Sechin River Basin and contains many buildings and plazas, as well as a fortified temple that has attracted much attention. The authors of the paper, who include Professor Ivan Ghezzi of the National Institute of Culture, Peru, believe the population was an ancient Sun cult and the observatory was used to mark special days in their solar calendar. Professor Ruggles said: “The western observing point, and to some extent, the eastern one, are very restricted – you couldn’t have got more than two or three people watching from them. And all the evidence suggests that there was a formal or ceremonial approach to that point and that there were special rituals going on there.

A lot of attention at the Chankillo site has focused on what is thought to be a fortified temple.

“This implies that you have someone special – the priests perhaps – who watched the Sun rise or set, while in the plaza next door, the crowds were feasting and could see the Sun rise, but not from that special perspective. Written records suggest the Incas were making solar observations by 1500 AD, and that their religion centered on Sun worship. “We know that in Inca times, towers were used to observe the Sun near the solstices, which makes you speculate that there are elements of cult practice that go back a lot further,” Professor Ruggles told the BBC News website.

Story from BBC NEWS:  © BBC 2011 


Tiwanacu (Tiahuanaco), Bolivia

1,500 BC is the “official age of ruins near Tiwanacu, however there is strong evidence that this site could be as old as 15,000BC …The main archaeological site at Tiwanaku has five primary structures, including the Akapana pyramid and the Kalasasaya temple. Less than a kilometre to the south lies Puma Punku, with its man-made platform and megalithic ruins. For centuries the sites have been looted, vandalized and used as a quarry for stone, and all the walls now standing have been reconstructed. Many of the statues were smashed during a campaign by the Catholic church to wipe out idolatry.  Excavations of the Akapana have revealed a sophisticated, monumental system of interlinked surface and subterranean water channels. Alan Kolata comments that the system, ‘although superbly functional, is over-engineered, a piece of technical stone-cutting and joinery that is pure virtuosity’.

Ruins of Tiwanacu

Drawing of the Kalasasaya by Squier, 1873
It shows there were 11 pillars (9 standing, 2 on the ground)

But it is an established fact that whatever calculation might be used to determine the age of the Temple of the Sun of Tihuanacu, on the basis of the variation of the obliquity of the ecliptic from those times until today, would demonstrate that [this] American solar observatory is more ancient than any monument of man in the world of which we know up to this time.“ 

– Arthur Posnansky
( Ancient Ruins of Tiwanacu and PumaPunku)


Ruins of Tiwanacu, Google Earth satellite view (top) and panoramic view (bottom). Click to enlarge.

Tiwanaku, Local Winter (summer in northern hemisphere)  Solstice. Click to Enlarge

Tiwanaku, Equinoxes. Click to Enlarge

Tiwanacu, Summer (Winter in Northern hemisphere) Solstice. Click to Enlarge

Alternative Observation Point.

Alternative Observation Point. It matches key dates (equinoxes and solstices) for sunrise (red lines).
There are 2 observation points and 26 “markers” (yellow) : (2 rows of 7 + 11 pillars +1 gate)  which mark sunset ( blue lines) and sunrise (red lines)on significant days of the year. Click to enlarge.

Jim Allen suggests that originally it was the extreme corner pillars of the Kalasasaya which were used to observe the sunrise (and/or sunset) at solstices. Solstice lines marked in blue, green and red [ from possible observation points] are parallel to lines of sight for solstices. Click to enlarge.

The Gateway of the Sun is carved with extreme precision out of a single block of very hard andesite granite. It is 4.7 m long, 2.2 m tall, and weighs about 10 tonnes. The top of the monolith has been broken, perhaps by an earthquake. The gateway displays intricate carvings and four deep rectangular niches, cut to an accuracy of ½ mm. Above the door is a frieze consisting of four lines of sculpture in low relief and a central figure sculptured in high relief, standing on a three-tiered pyramid.

Sun-god Viracocha from the Gate of the Sun is the personification of the Sun.
provides the key to understanding astronomical significance of Tiwanacu.

The figure is widely believed to represent Viracocha, or the Aymara weather god Thunupa, and is sometimes called the ‘weeping god’ and likened to the ‘staff god’ of the Chavín culture. Its elaborate headdress has 24 ray-like projections ending in circles or puma heads, and it holds two staffs ending in condor heads. On either side of the central deity are a total of 48 other figures, arranged in three rows (8 per row); the outermost figures are unfinished. They include 30 winged attendants, or ‘angels’, with human or avian heads, who are either kneeling or running. In addition to the central figure, there are also 11 other frontal faces with solar masks, located in the lowest row of the frieze (the ‘meander’). Some scientists believe that these figures represent a solar calendar with 12 months and 30 days in each month.

Let’s have closer look at the frieze of Sun-god (notice 17 rays with rings at the and and 6 puma heads; 24 segments around the head in total counting the “small head” in the middle).

Click on images below to enlarge.

Another stonework at Tiwanaku
showing of almost identical image
of the Sun-God Viracocha


This wonderful graphic by Ken Bakeman
shows colored version of the Sun-god
from the Gate of the Sun relief.
Image source:


On the Gateway of the Sun, the famous carved figure on the decorated archway in the ancient pre-Incan city of Tiwanako most likely represents Wiracocha, flanked by 48 winged effigies — 32 with human faces and 16 with condor heads.

The photo of the frieze with superimposed colors marking repetitive “modules” (Click to enlarge)

Graphic showing part of the frieze with winged figures converging on the central deity

 Artur Posnansky  was one of the first explorers who discovered there was obvious connection of the Tiwanaku’s architecture with astronomy. The image below explains his interpretation of the Gate of the Sun  as a calendar.

Arthur Posnansky’s calendrical interpretation of the frieze (Notes on Peruvian antiquities, pp. 445-7). Click to enlarge.

Jim Allen discovered the Gate of the Sun is not the actual calendar but the key to operating the calendar… Here is what he writes:

Many people have stood in front of the massive stone monument known as the “Gate of the Sun” in the ancient city of Tiwanaku in the Bolivian Andes. They admire the craftsmanship of the small carved figures known as “Chasquis” or “Messengers of the Gods” and ponder over the use of the gate as an ancient calendar. But in fact, the gateway itself is not the calendar, the calendar is a little known row of 11 giant upright stones, now built into a wall which exists just behind the gateway. Today, there are only 10 stones in the wall and the missing 11th stone lies face down some distance out in the field behind the wall. When the 11 stones were in their original positions in a row, the sun would set each evening over the row of stones so that priests standing in the centre of the adjacent courtyard could easily calculate the time of the year in a remarkable calendar which divided the year into 20 periods of 18 days and also meshed with a lunar calendar so that three solar years equalled 40 sidereal lunar months which was 2 “zocam” years and even more remarkably it also meshed with a Muisca lunar period of 37 months. This meant that every 30 solar years was at the same time 20 Muisca Zocam years of 20 sidereal months of 27.32 days and 10 Muisca Acrotom years of 37 synodic months of 19.53 days. Additionally every thirty years an extra month had to be added to both lunar calendars to keep them synchronised with the solar calendar and this is commemorated in the Gateway of the Sun with thirty Chasquis marking the solar years and forty condor’s heads marking the lunar months. So the Gate of the Sun is not the actual calendar but the key to operating the calendar…

 – – –

The following is part of the article by Jim Allen

Copyright Jim Allen, Presented with Permission of the Author

LOST CALENDAR OF THE ANDES, the calendar of Tiwanaku and of the Muisca

Jim Allen is author of “Atlantis: the Andes Solution” and “Atlantis: Lost Kingdom of the Andes” (Floris Books, 2009)


In the year 2,000, I found myself in Tiwanaku with the Discovery Channel filming for “Atlantis in the Andes” and in the company of Oscar Corvison, a Bolivian Archeoastronomer who was keen to explain his interpretation of the vigesimal (base 20) system of the Tiwanaku calendar.  Oscar explained that it was not the Sun Gate which was the Tiwanaku calendar, but a wall which today is to one side of the Sun Gate, inside a courtyard called the “Kalasasaya”. He was particularly upset because he said, in the reconstruction of the western wall of the Kalasaya, one of the large stones which had originally been part of the calendar had not been restored, but left laying in a field a couple of hundred metres to the west of the wall.

The Gate of the Sun with the calendar wall behind. The position of the missing pillar is arrowed.

Oscar Corvison shows us the missing pillar in the field behind.

View from the field showing the reconstructed wall, the position of the missing pillar can be easily seen, just behind where the person appears to be running.

Oscar gave me a self-produced booklet which explained how the wall functioned, and it seemed simple enough to understand that the year had been divided into 20 parts as he claimed, so I thought no more of it until the end of December 2008, when it became necessary to give some book references to my editor who was going over the draft of my “Atlantis: Lost Kingdom of the Andes” for publishing on 21 May 2009 by Floris Boooks.

Since my own fascination is for ancient measurements rather than calendars, I began to study Posnansky’s measurement of the wall, and discovered the wall was not simply a solar calendar as had been previously thought, but incorporated a sophisticated calendar based on sidereal lunar months.
The rest of this essay and the discovery of the sidereal lunar calendar follows on from Oscar Corvison’s pioneering discovery of the base 20 system in the Tiwanaku calendar.

Tiwanaku Calendar

The stone gateway which is today in the Kalasasaya is baptised ‘the Gate of the Sun’ and ‘Kalasasaya’ according to Arthur Posnansky who spent a lifetime studying the site, simply means ‘standing stones’. When he investigated Tiwanaku the stone pillars had more of the appearance of a ‘Stonehenge’, there was no wall there as there is today, (most of the wall was assumed to have been carried off so in the 1960’s as part of a reconstruction project the spaces between the pillars were filled in to form a wall, at the same time the Gate of the Sun was moved to its present position inside the Kalasasaya and next to the calendar wall) and only 10 of the giant pillars remained. The 11th missing pillar may be found laying face down in a field some 229 metres to the west. According to Oscar Corvison, a Bolivian archeo-astronomer who studied the site, the eleven pillars represented the division of the year into periods of 20 (Corvison 1996). This seems more logical, since if you count from the central pillar (representing the equinox) out to the end pillar on the right (representing the north solstice), then back past the centre to the far left pillar (representing the south solstice), then back to the centre again, you arrive at a division of 20.

 This is how it works. In the centre of the Kalasasaya courtyard there is a large block of stone which is said to represent the original observation point. From here the sun could be watched setting on the horizon over the pillars each night. When the sun set over the central pillar, the day would be the 22nd September (equinox) and Spring would begin (seasons reversed in southern hemisphere). . When the sun set over the next pillar to the left, one twentieth of a year would have passed and so on until reaching the pillar at the far left a quarter of a year later on the 21st December marking the Summer Solstice.

This satellite image shows the Kalasasaya courtyard with the calendar wall to the west and the observation stone marked the viewing position. Click to enlarge.

Photo-reconstruction showing the wall with the missing pillar restored.
The pillars seen in plan view. The sun follows the numbering as shown below from 1 to 20.

The sun would now begin to move back towards the centre, reaching here another quarter of a year later on March 22, marking the Autumn equinox, then it would continue to the right, reaching the end pillar on June 21st marking the winter solstice and the beginning of the Aymara New Year (the great festival of Inti Raimi when the sun appears to “stand still”) and returning back over the centre pillar one year later on the following 22nd September to mark the beginning of another Spring. (Explanation thanks to Oscar Corvison).

Posnansky seems to have considered the row of pillars as representing a calendar based upon a month of 30 days – probably because 30 small figures called “Chasquis” appear on the Gate of the Sun – and states that the solar year of twelve months was used with the sun showing through the gap between the pillars each month. But there’s a flaw with that. With eleven pillars, there are only 10 gaps or spaces, not 12 …

 In order for this type of calendar to count twelve months, it would have been necessary to construct thirteen pillars, not eleven and a row of thirteen towers has recently been found in Peru, which according to the system above would represent the division of the year into 24 and correspond to 12 solar months, suggesting the ancient calendar was later reformed into 12 months of 30 days which may have misled some scholars in their attempts to understand the original Andean calendar. (see “Chankillo”  report we mentioned earlier)
Posnansky would have done better to pay attention to one of his own quotes, in section E, note 78 of his own book “Tihuanacu, the Cradle of American Man” where he quotes a sixteenth century Peruvian historian as saying ‘They divided the year into twelve months by the moons. Already each moon or month had its marker or pillar around Cuzco, where the sun arrived that month.’ (Ondegarda 1571)

The Inca were sometimes said to be people of the sun, whereas the Aymara were sometimes said to be people of the moon, so I wondered whether in fact the pillars may also have been a soli-lunar calendar since what is called the ‘Saros’ cycle of lunar eclipses repeats itself every 20 ‘Inca’ years and 20 ‘Inca years’ of 12 months of 27.32 days is very close to 18 solar years of 365.24 days (Allen 1998 and Aveni 1990) and the people who built Tiwanaku were a race long before the Inca and possibly even before the Aymara. On the other hand, if used for agricultural purposes, it may simply have marked the winter and summer solstices with the appropriate pillar or space between the pillars marking the return of the sun to a suitable time for plantings crops, which is what Posnansky thought the purpose of the calendar was in the first place.

Although Corvison was correct in identifying the use of a solar calendar based on divisions of 20, (and this should not be a surprise since both the Aztec and Maya civilisations used a base 20 calendar) he does not seem to have considered the possibility it could also have been a lunar calendar.

 Although Corvison was correct in identifying the use of a solar calendar based on divisions of 20, (and this should not be a surprise since both the Aztec and Maya civilisations used a base 20 calendar) he does not seem to have considered the possibility it could also have been a lunar calendar.

When the sun crosses from the centre to the first pillar, 1/20th of the solar year has passed giving a month of 18 days counting the year as 360 days. The remaining 5¼ days are “lost” when the sun stands still at each end of the calendar.

Tiwanaku lunar calendar. When the sun has crossed 1½ pillars, one sidereal lunar month will have gone by.

On the above basis, when the sun reached the first pillar it would have travelled a 1/20th of a solar year which is 18.26 days. By the time it reached midway to the next pillar, it would have travelled half as much again, which when added to the first figure means 27.39 days would haved passed — virtually a sidereal lunar month —   every one and a half pillars would add another sidereal month and continuing the process would take us back to the central pillar after 13 and a third such sidereal lunar months (or divisions) had passed, completing a solar year and making it a dual purpose, soli-lunar calendar.

Click to enlarge this animation.

Now I wondered if this in some way tied in with the Saros cycle and since it takes thirteen and a third sidereal lunar months to circle round the calendar stones in order to complete one ‘lap’ and come back to a full year, how many ‘laps’ would it take to fulfil the Saros cycle?

Well, three ‘laps’ round the pillars would make the sun once more over the central pillar and represent 40 sidereal lunar months and since each lap around the pillars is a solar year, a total of 18 ‘laps’ round the pillars would complete the Saros cycle, the sun would be back again over the central pillar and the cycle would all begin all over again!

Maybe that’s why the Amautas (mathematicians) of the Aymara thought they had discovered the most perfect calendar in the world. Could this be the calendar of Atlantis? Some people thought so (Corvison 1996), but they failed to realise the Altiplano was Atlantis.

In addition to counting the Inca lunar year of 12 sidereal lunar months (328 days) the calendar also represents a year of 360 days as well as a year of 365.24 days. How it could do that may be something like this. From the centre to the centre of the end pillars is taken as 360 days (counting from one end to the other end then back again) then the distance from the outside to the outside of the opposite pillar (and back again) would represent 365.24 days. In this way, the calendar could mesh the Solar calendar with the Lunar calendar, the extra five and a quarter days being ‘lost’ (to view) when the sun reaches the end pillars and appears to stand still before returning in the opposite direction. Each division from pillar to pillar would be 18 days, which could be arranged in groups of 2 x 9 days.

It seems that in the Andes, a work period of six weeks of nine days was used, which would therefore correspond to three divisions of the pillar calendar and be two sidereal lunar months.

The key to the calendar was said to be built into the Gate of the Sun, today found near the Kalasasaya pillar wall and put there when the Kalasasaya was restored. It consists of a giant block of stone with a gate cut into its lower half and an elaborate decoration on the upper part. In the centre of the decoration there is a representation of the ‘weeping’ god — presumably Viracocha and in his hands he carries two staffs, which look like measuring or mathematical staffs since although the rest of the monument is symmetrical, the staffs are different, the one in his right hand has two sets of three circles and the one in his left hand has two vertical lines over three circles. But who can read the monument today?

The upper part of the Gate of the Sun shows the key to using the calendar. Click to enlarge.

On the upper level, on each side there are three rows of iconic figures called ‘chasquis’ — messengers of the gods, each row has eight chasquis, but it is thought that the outer three were meant to be a continuation on the walls each side of the gate which today are missing. They are arranged so that each side of the central figure there are two blocks each of three rows of five chasquis. It can also be noted that two rows of two x five of the chasquis making twenty chasquis have faces looking forwards and one row of two x five chasquis making ten chasquis has condor heads looking upwards.

The frieze with eleven icons represents the eleven pillars of the wall.  Lower image highlights the continuous “flow” of the “maze” line. Click to enlarge.

Beneath these chasquis there is a continuous row of smaller icons arranged so that eleven of them stand apart from the rest. We can assume that these eleven represent the pillars of the calendar. Now it has usually been wrongly assumed that because the upper chasquis in horizontal rows total fifteen on each side (not counting the outer ones) that the total of thirty chasquis represent a month of 30 days since a solar year of 360 days divided by 12 months would give a 30 day month. But as explained above, the actual calendar is divided by 20, which would make solar divisions of 18 days. And work periods of 18 days were used in the Andes.

The reason why people can’t see the correct number of chasquis on the lower freize of the Sun Gate is because the eleven chasquis in a row represent a circular or elliptical orbit, so the two end chasquis represent the solstices when the sun reaches the ends of the orbit, but the remaining nine chasquis conceal another chasqui behind them so to speak (if viewing the orbit in plan view) so the total is two end chasquis plus eighteen ‘double’ chasquis making 20 all told.

Apart from the end chasquis, each chasqui conceals a twin behind it representing the same position on the other side of the orbit. Click to enlarge.


This is clearly shown on the freize itself where there is like a route marked round the chasquis telling you to go round the calendar in an orbit, then there are 20 condor head symbols in pairs on the upper part of the freize, and 20 condor head symbols on the lower part of the freize in pairs, telling you to count in twenties and forties.

The frieze shows forty condor heads in two rows of twenty also indicating that the calendar is based upon divisions of twenty. Click to enlarge.

Many people have mistakenly thought that the Gate of the Sun was the calendar, but it isn’t. The pillar stones built into the west wall are the calendar and it could be instead, that the chasquis are telling you how to operate the calendar.

Instead of reading horizontally, if we read vertically, they seem to be saying, ‘count in blocks of three.’ But blocks of three what? When we studied the operation of the stones on the wall, we found that every one and a half pillars represented one sidereal lunar month. Therefore every half division between the pillars represented one fortieth of the year or a third of a sidereal lunar month, the month itself being the prime unit. Now on the Gate of the Sun there are a total of 48 Chasqui icons which could therefore represent 48 sidereal lunar months. Tahuantinsuyo, the empire of the Incas was ‘the land of the four quarters, or four divisions’ so dividing the 48 Chasquis by 4 results in 12 Chasquis — meaning 12 sidereal lunar months — which was the Inca lunar year of 328 days. In turn 328 days divided by 4 gave the 82 day (three month) period at the end of which the moon would be visible against the same group of stars etc and that I believe, is the message of the Chasquis — how to operate the calendar.

Above, the “Gate of the Sun” at Tiwanaku, Bolivia, the 30 Chasquis represent 30 Solar years,  equal to 20 Zocam years of 20 sidereal lunar months or 10 Acrotom years of 37 synodic lunar months. At the end of this period, 1 x lunar month had to be added to the lunar calendars to bring them back into phase with the solar year… Beneath the chasquis can be seen the freize with 11 smaller chasqui heads representing the 11 pillars on the calendar wall which in turn divide the solar year into 20 months of 18 days, and the 40 condor heads represent the 40 sidereal months which mesh with the solar calendar every three years.

The 30 Chasquis represent 30 Solar years, equal to 20 Zocam years of 20 sidereal lunar months or 10 Acrotom years of 37 synodic lunar months. At the end of this period, 1 x lunar month had to be added to the lunar calendars to bring them back into phase with the solar year…

Above, when the sun reached the end of the pillars, it appeared to “stand still” before beginning its journey back in the opposite direction.

Copyright Jim Allen
Presented with Permission of the Author

Books by Jim Allen

 Note: More about this and other calendars will be posted soon in Part 4

– – –

Mayan Astronomy

The Maya were expert sky-watchers, careful observers of the motions of the celestial bodies. Proof of the Mayan fascination with astronomy is literally carved in stone in the grand architecture at sites such as Teotihuacan, Chichén Itzá, Uxmal, Uaxactun, Edzna, and dozens more. At many of these sites, hieroglyphic carvings refer to celestial bodies and cycles. Often, the buildings they adorn have been built to align with significant cyclical astronomical events — solstices, equinoxes, the shifting moon, or the rise of planets and stars.

Some ancient observatories were located in flat, desert-like areas (e.g. Teotihuacan), other (e.g. Chichen Itza,  Tikal) were built in a jungle and required very tall foundations for observation platforms and pyramids in order to observe  the sky from above the jungle canopy.

Slim and Tall structures of Tikal allowed observing the sky without obstruction of the jungle trees.

“El Caracol” and  El Castillo at Chichén Itzá

Teotihuacan, Mexico

The city of Teotihuacán is meticulously laid out on a grid which is offset 15º.5 from the cardinal points. Its main avenue, the “Street of the Dead,” runs from 15º.5 east of north to 15º.5 west of south, while its most impressive structure, the Pyramid of the Sun, is directly oriented to a point 15º.5 north of west — the position at which the sun sets on August 13.

Teotihuacan’s orientation commemorates August 13th, “the day the world began” according to the ancient Mesoamericans!
The bottom image show in orange sunset on Aug 13.
Note: There are 15 platforms surrounding pyramid and platform in the middle.

Here, on the Plateau of Mexico, cityplanners had built a ceremonial center with a configuration commemorating a date whose calendrical importance had first been recognized 1000 km (600 miles) away to
the south more than a millenium earlier. And, in addition, they had located the city with such precision that it was also aligned to the highest mountain in all of Mexico at sunrise on the winter solstice –Citlaltépetl, or Orizaba (5700 m, or 18,700 ft. in elevation). To be sure, a low ridge obscures the mountain from the direct view of anyone standing atop the Pyramid of the Sun, but the alignment is so exact that in a paper published in 1978 I hypothesized that a “relay station” of sorts must have been constructed on the intervening ridge to alert the priests of the solsticial sunrise. In January, 1993, with the help of a GPS (i.e., global position-ing system) receiver I managed to confirm that such a “station” had in fact existed.  — Professor Vincent Malstrom.

There is no doubt that the Palace of Quetzalcoatl and the surrounding platforms functioned as an astronomical observatory (and calendar). The strong clues come from the direction of the sunrise and sun set on key days over the year. We suggest that the platforms were used for observing not only the sun but also the moon and the stars. Below are few undeniable examples.

In 2011 the September equinox occurs on September 23, 2011.
The Sunset-Sunrise lines remain exactly the same for the Spring Equinox (in 2011 on March 20).
Also the rising Sun is aligned with one of  the pyramid steps.
Click to enlarge!

In 2011 the Winter Solstice occurs on Dec 22.
The leftmost platform is aligned with the setting Sun when viewed from the observation platform. Also the rising Sun is aligned with one of  the pyramid steps. Click to enlarge!


Edzna, Mexico

This is a Maya archaeological site in the north of the Mexican state of Campeche. The most remarkable building at the plaza is the main temple. Built on a platform 40 meters high, it provides a wide overview of the surroundings. It was one of the Mayan astronomical observatories.

Edzna archaeological site. Credit: Wikipedia


Edzna Map

On the east side of the plaza, a large staircase ascends into the Great Acropolis, of about 10 structures standing on a raised platform about 170 meters to a side. Medium-sized pyramids topped by temples flank the stairs to the left and right, and in the center is a square altar platform. After that stands the large Building of the Five Stories, also called the Palace. 

“The Temple Of The Five Floor Building”.  Image by G. DeLange

The Temple Of The Five Floor Building

The Palace faces west and is aligned so that on May 1 and August 13 at the suns zenith at this latatude -the setting sun shines into its rooms.


The gnomon at the base of Edzná’s principal pyramid,“Cinco Pisos”. It consists of a tapered shaft of stone surmounted by a stone disk having the same diameter as the base of the shaft. At noon on the days of the zenithal sun passage, the entire shaft is in the shadow of the disk; at other times, the shaft itself casts a shadow, as in the photograph above.  Photo by Professor Vincent H. Malmström Source:

 Astronomical alignment on days of Solstice. Edzna was a luni-solar observatory. Click to enlarge.

Edzna, Casa Grande is in front of the Cinco Pisos. This is an obvious component required for “naked-eye” horizon based astronomy.

 The astronomical importance of Edzná may be gauged from these facts:

  1. only at its specific latitude could the beginning of the Maya new year be calibrated, here with the assistance of a remarkable gnomon;
  2. the “day the world began” was commemorated in the “gun-sight” orientation between the doorway of Cinco Pisos and the small pyramid across the plaza; and
  3. lunar cycles were measured by using the line of sight between Cinco Pisos and “La Vieja” on the northwestern horizon.

Although we cannot be certain when the Maya finally succeeded in working out the lunar eclipse cycle, it would seem that most of the basic “research” on the problem was carried out at Edzná. Located some 300 m (1000 ft) to the northwest of Cinco Pisos is the ruin of a lofty pyramid which Matheny has termed “La Vieja,” or the “Old One.”[…] Even in its dilapidated condition it is still high enough to intersect the horizon as seen from the top of Cinco Pisos; indeed, it is the only manmade construction which does so. This fact immediately prompted me [Dr. Vincent H. Malmström ] to measure its azimuth as seen from Edzná’s commanding edifice, and the value I obtained was 300º. This means that the summit of the pyramid lies exactly 5º beyond the sun’s northernmost setting position at the summer solstice. Because the moon’s orbit is just a hair over 5º off that of the sun, it seems very likely that the Northwest Pyramid, or “La Vieja,” had been erected as a horizon marker to commemorate the moon’s northernmost stillstand. Not only is “La Vieja” an eloquent testimonial to the patience and accuracy of Maya “science,” but because of its specialized function, it is also probably worthy of being designated as the oldest lunar observatory in the New World. (Indeed, if Matheny’s dating of “La Vieja” is accurate, then it is apparent that the Maya had succeeded in measuring the interval between lunar stillstand maxima at least by A.D. 300.)

Source:  Calendar Reform and Eclipses-  The Place of Edzná

Chichen Itza, Mexico

As practitioners of naked-eye, horizon-based astronomy, it is obvious that the Maya never recognized the existence of “nodes”, or points where the moon’s orbit intersected that of the sun; the simple reason was that they had no means of defining any celestial position other than the zenith. At least by marking the northernmost setting point of the moon against the horizon they obtained a fixed point from which they could count the number of days that elapsed between two lunar events.  For the Maya the easiest way to record spatial observations — other than by framing them against a prominent topographic features — was by erecting durable markers of their own in the landscape to calibrate the rising or setting azimuths of the sun, moon, planets and stars.

El Castillo, Chichen Itza, Mexico (Image Copyright

The Maya were known to be great mathematicians and are credited with the invention of the “zero” in their counting system. They were also great astronomers, and EL Castillo is a perfect marriage of their sciences with their religion. By far the most amazing aspect of the pyramid is the accuracy, significance, and relevance it has within the Mayan calendar and social system. There are many numerical details regarding the location of this structure that could not have all occurred by accident. Each side of the pyramid is made up of nine larger tiers or layers with a staircase in the center of each side leading to the temple at the top. Each stairway consists of ninety one steps, with one step at the top common to all four sides, for a total of three hundred and sixty five steps, the exact number of days in a solar year. Each side of the pyramid has fifty two rectangular panels, equal to the number of years in the Mayan cycle (at the conclusion of which they typically constructed a newer structure over an older one). The stairways divide the tiers on any given side into two sets of nine for a total of 18 tiers which corresponds to the 18 months in the Mayan calendar. The “square” that makes up the overall base of the structure is exactly 18 degrees from the vertical. Every aspect of the structure relates in some way to the Maya and their culture. The very physical presence of this structure and the shadows it casts, are also significant within the Mayan culture and are more fully explained in here the section detailing the Shadow Of The Equinox.

The Maya universe was comprised of 13 “compartments” in 7 levels with each compartment being ruled over by a different god. El Castillo reflects these beliefs as seen in the shadows it casts. 7 levels are shown in the 7 light triangles. 7 Triangles of light and 6 darker triangles give 13 triangles in all corresponding to the 13 overall levels of the underworld.

Suffice it to sum up here and say, the pyramid casts unique and identifiable shadows on the exact days of the year that represent the solstice and equinox that occur twice a year. This shows the Maya were aware of the rotation of the sun and the exact length of a year. Indeed, we know that the Mayan Calendar was more accurate than the one we use today.

The phenomenon that El Castillo is famous for occurs twice each year, at the spring and fall equinoxes. (In fact, the effect is viewable for a week before and after each equinox.) As the equinox sun sets, a play of light and shadow creates the appearance of a snake that gradually undulates down the stairway of the pyramid. This diamond-backed snake is composed of seven or so triangular shadows, cast by the stepped terraces of the pyramid. The sinking sun seems to give life to the sinuous shadows, which make a decidedly snaky pattern on their way down the stairs.


Other features of El Castillo suggest astronomical understanding and intent on the part of the Mayan builders. The structure as a whole seems to be aligned with an important astronomical axis: The west plane of the pyramid faces the zenith passage sunset. Meanwhile, each of the four (exceedingly steep) stairways that climb the pyramid has 91 steps, with a final step at the top making a total of 365, the number of days in a solar year. Ninety-one is also the number of days that separate each of the four phases of the annual solar cycle: winter solstice, spring equinox, summer solstice, and fall equinox.

Using the patterns of light and shadow appearing on El Castillo throughout the year, the Maya could easily have tracked the seasons and marked these four annual solar events—the two solstices and two equinoxes. And so it seems the ancient Maya may have used this structure as, among other things, a calendar to signal appropriate times to plant, harvest, and perform ceremonies.

El Caracol seems to be carefully aligned with the motions of Venus. Venus had tremendous significance for the Maya; this bright planet was considered the sun’s twin and a war god.
The grand staircase that marks the front of El Caracol faces 27.5 degrees north of west—out of line with the other buildings at the site, but an almost perfect match for the northern extreme of Venus, Venus’s most northerly position in the sky. Also, a diagonal formed by the northeast and southwest corners of the building aligns with both the summer solstice sunrise and the winter solstice sunset.

Image Source:

Image Source:

In the half-ruined higher tower of El Caracol, three openings survive. These three openings are small, narrow, and irregularly placed, suggesting that they are actually viewing shafts. It turns out that these windows do in fact align with important astronomical sightlines. Looking through these windows a thousand years ago, observers could have watched for Venus rising at its northern and southern extremes, as well as the equinox sunset. The three window shafts that remain in the upper tower of El Caracol seem to align with various celestial events on the horizon.

Image Source:

At Chichén Itzá, the zenith passage is experienced on May 23 and July 20, give or take a day.

Parts of the above segment belong to

Tikal, Guatemala

The erection of five great pyramids, all of them more than 60 m (200 ft) in height (this was required to view the sky over the jungle canopy, ofter shrouded in fog) has to be one of the most impressive accomplishments of any early people in any part of the world. The spectacular grandeur of Tikal is in large part a result of this remarkable engineering triumph. But what makes this accomplishment even more impressive is that all five of these pyramids were conceived and built with such exacting precision that they continue to function as a giant astronomical matrix to this day!


While it may be of interest to know that some of the pyramids of Tikal also served as the final resting place of members of the Mayan elite, their primary function was to serve as observation platforms for priests working with the calendar.

Dr. Malmström discovered that pyramids had been constructed as an astronomical matrix whose purpose it was to calibrate the most important dates in the Maya year.

The five major pyramids of Tikal were all constructed within a 40-year period beginning in the mid-eighth century A.D., apparently as part of an ingeniously designed astronomical matrix.

The sight-line between Temple I and Temple IV (the highest of the pyramids) marks the sunset position on August 13, whereas the sunrise position at the winter solstice is perpetuated in the sight-tine between Temple IV and Temple III. Because Temple I and Temple III are sited due east-west of each other, they mark sunrise and sunset alignments at the equinoxes. Although there was no star located directly above the earth’s pole of rotation in Maya times, a sight-line from Temple V to Temple II appears to have marked the most westerly position of the Maya’s equivalent to a polestar, Kochab.

The western horizon at Tikal as seen from Temple I. The low, squat structure in the middle foreground is Temple II, which serves not only as an architectural counterweight to Temple I as seen across the plaza of Tikal but also as a horizon marker for the enigmatic “8º west of north” orientation when viewed from Temple V. The latter orientation was present at La Venta about 1000 B.C., but also shows up at the Maya capital about A.D. 800. Farther to the left, Temple III defines the equinoctial sunset position as seen from Temple I, while the highest of the skyscraper pyramids — Temple IV, on the right — fixes the sunset position on August 13 as seen from Temple I.



The Giza Pyramids

“…it appears that there was drawn a plan of the Great Pyramid which included the calculation of the stars to be observed in order to obtain the direction of the north. After this plan was drawn, the ground of the Pyramid had to be cleared in order to proceed to the ceremony called “stretching the cord,” which for the Egyptians was the equivalent of our laying of the first stone. This ceremony had the purpose of establishing the direction of true north and, as the Egyptians saw it, suspending the building from the sky by tying the building with an imaginary string to the axis of rotation of the vault of heaven.” (Tompkins, Secrets of the Great Pyramid, pp. 380 and 381). 

In ancient Egypt rope stretchers were surveyors who measured property demarcations and foundations using knotted cords which they stretched in order to take the sag out of the rope. When performed by kings during the initial stage of temple building the Stretching of the Rope was probably a religious ceremony rather than a surveying job.

 Egyptian architects, surveyors and builders are known to have used two specialised surveying tools, the merkhet (the ‘instrument of knowing’, similar to an astrolabe) and the bay (a sighting tool probably made from the central rib of a palm leaf). These allowed construction workers to lay out straight lines and right-angles, and also to orient the sides and corners of structures, in accordance with astronomical alignments. ( Read more about orienting pyramids here: )

It is clear that the Egyptians were using their knowledge of the stars to assist them in their architectural projects from the beginning of the pharaonic period (c.3100-332 BC), since the ceremony of pedj shes (‘stretching the cord’), reliant on astronomical knowledge, is first attested on a granite block of the reign of the Second-Dynasty king Khasekhemwy (c.2650 BC). Some of the Ancient Egyptian architecture was used for calendric (timekeeping ) purposes. 

It seems that Egyptian pyramids layout was designed to mark key dates in Egyptian calendar by position of the rising and setting sun ( just like in the case of the pyramid of Kukulcan in Chichen Itza).
It also appears that shadows of the Giza pyramids were designed to mark the key calendar dates.

From a very early time, the ancient Egyptians had a form of calendar based upon the phases of the moon followed by a solar calendar system of 360 days, with three seasons, each made up of 4 months, with thirty days in each month. The seasons of the Egyptians corresponded with the cycles of the Nile, and were known as Inundation (Akhet which lasted from mid June  to October ), Emergence (Perety which lasted from mid October to February ), and Summer (pronounced Shemu which lasted from mid February to June ).


Sunrise over the Pyramids

Sunset on February 15 (first day of harvest season Shemu)

Sunrise on Feb 15 – Sun is rising over the causeway

Evening shadows on Dec 21 solstice. Two images superimposed to show shadow at two different times. Shadow of the Second Pyramid touches the corner of the First Pyramid and later both shadows align.


To be continued — we are preparing much more material on this subject…

Related Links

 Archaeoastronomy Resources

Lists of General Archaeoastronomy Links

Native American/ MesoAmerican Archaeoastronomy

Archaeoastronomy of Prehistoric Britain and Ireland

World Archaeoastronomy


  1. Goczey András says

    The three big pyramids are a time keeper!
    Mykerinos is the 28 days for the whole year “Menkaure hidden calendar” ,
    Khefren is twice 6-6 months for the year “Nabta Playa Giza”, and
    Khufu is the four time to show the date for the year. “Khufu hidden calendar”
    I can sand it to you these interesting places to know how in order to show the days how they run!
    Andras G?czey from Budapest

  2. says

    This “Ancient Time Keepers” article is so intense, I need to read it again some other time because it is too much to take in on one night.

    Thank you so much for all the effort and scrutiny you put into this!

    All the best,


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