Avebury and Newgrange as Planetary Calendars

Big Stones! Avebury

In the category ‘my hunebed’ we invite people to write about their own personal thoughts about hunebeds and megalithic monuments. Here is a story of Peter van den Hoek.

Article version: 27-11-2021

Peter van den Hoek

For many years I have been researching the mystery behind stone circles, dolmens and other structures from the Megalithic Culture. These thousands of years old structures reveal again and again in their orientation that their builders tried to capture the movements of celestial bodies in huge structures of stone.

In the stone circle of Avebury (98 stones) and the kerbstones around Newgrange (97 stones) the different cycles of the visible planets (mercury, venus, mars, jupiter and saturn) seem to have been recorded. In this article, I’m going to explain how I see this.

South Circle Avebury


Let’s start with the stone circle of Avebury in Great Britain, see ground plan. This is the largest stone circle in the world with a diameter of no less than 330 meters. Presumably, it was built around 2800 BC. and therefore about 300 years older than the nearby Stonehenge¹.

Looking at the ground plan, this stone circle seems to be made up of two small circles within a large circle. The two small circles like to tell us something about the moon. The upper circle (North Circle) consists of 27 stones and that is the period of a sidereal month. This is the period in which the moon again occupies exactly the same position between the stars.

The lower circle (South Circle) consists of 29 stones plus one stone that is placed slightly inwards. This is the period of a synodic month (29.5 day), or from full moon to full moon, that we know best. The moon is then in exactly the same position viewed from the earth-sun perspective.

In this circle stood the largest stone of the entire complex, on the spot where a concrete obelisk (The Obelisk) now stands. Due to its size, this huge stone emphasized this synodic circle and thus formed in my opinion an indication that a synodic cycle could also be referred to in the outer circle.

While puzzling, I discovered that when these 98 stones are multiplied a number of times you get remarkably close to the synodic cycle of the visible planets, see the table below. These are mercury, venus, mars, jupiter and saturn.

Especially for venus, mars and jupiter, the difference is very small with the average from the table. In reality, the successive synodic cycles of a planet also differ by a number of days.

It is also not at all difficult to arrive exactly at the average in counting, because this can be achieved simply by counting the number of stones and therefore days forward with a plus number at the end (see table) in the first round and counting backward the number of stones/days with a minus number.

Let’s take venus as an example: For this planet make 6 rounds multiplied by 98 rocks/days 588 days. On average, venus does 584 days over this cycle, so that’s 4 days (+4) too much. By counting 4 days/stones forward in the first round, this problem is solved just like that.

There could have been counted with a different type of rock for each planet and the number of rounds could have been tracked by adding one extra stone for each new round.

Presumably, the Aubrey circle of the nearby Stonehenge had a similar function for tracking lunar standstills (two rounds) and eclipses (four rounds). In my documentary about Stonehenge¹ on Youtube I explain this further.  

Let’s return to the huge stone on the spot where the obelisk now stands, see ground plan. I believe that this place was the center to observe the setting of the sun, moon and the visible planets.

From this point, looking west, you could see every synodic moonset, for example, when the moon was full. In winter, the full moon sets the northernmost and two weeks later the southernmost. The builders of Avebury knew that every year this point moved a little more towards north and south until an extreme position was reached. We call this a major lunar standstill. After this, the moon returns annually to its least northern and southern setting point. We call this a minor lunar standstill.

The shortest period between these two standstills is exactly 9 years and that has been recorded by the builders in a row of 9 stones in front of the obelisk, see ground plan. The first stone indicates the place where the moon sets the southernmost during a major lunar standstill. The ninth stone is the place where the moon sets the northernmost during a minor lunar standstill.

Also, the northernmost sunset during midsummer is marked by the builders with a stone on the right side diagonally above the just mentioned ninth stone. When you look over this stone from the obelisk, the sun sets exactly there on June 21 every year.

In a stone construction in the north circle called ‘The Cove’ the sunrise during midsummer is recorded. The sun then illuminates exactly the front of stone 2 on June 21 during rise. Perhaps there was even a capstone on this construction to make the light spectacle even more beautiful?!?

From the huge stone at the site of the obelisk, I think the sets of the visible planets (mercury, venus, mars, jupiter and saturn) in the west was also observed. Especially the moment that they could be seen again after a period of overexposure by the sun during their set was probably well kept. A synodic cycle had been completed and the counting could then start again, as is the way with every calendar.

I can well imagine that the two stones on either side of the western entrance were used as the first (1) and last (98) counting stones to record the number of days between two synodic cycles of a planet when it sets. That is why my count of the stones also starts and ends there, see ground plan.

As with the moon, the setting point of the visible planets differs from each synodic cycle. Yet, in practice, the various planets never set further north or south than the moon does. In this way, the 9 stones in front of the obelisk help to indicate roughly in which angle a planet will set. Stone 1 even indicates this very precisely. It is also very coincidental that the outer circle in line with this stone exactly makes a bend at the point of stone 83. Or was this done intentionally?

Outer Circle Avebury


With this knowledge in mind, let’s look at the dolmen with huge mound of Newgrange in Ireland. The dolmen itself with a length of 24 meters is presumably aligned with the sunrise during midwinter on December 21. The mound has a diameter of no less than 80 meters. This structure was probably built around 3200 BC. and therefore about 400 years older than Avebury.

Around the huge mound there are 97 kerbstones and that differs only one stone from the large circle of Avebury. Could it be that these stones were also used as a counting system and calendar to count the synodic cycles of the visible planets? I think so. In the table below this is worked out in numbers.

The synodic cycle of venus is almost exact here, except for 2 days. On a cycle that lasts more than a year and a half, two days is of course negligible. Venus is a special planet! After sun and moon, venus is the brightest object in the sky. The Mayas were completely fascinated by this planet and even developed their own calendar system for it of 260 days (Tzolkin), the period where venus could alternately be seen as a morning star or evening star.

Would the builders of Avebury and Newgrange have had the same kind of fascination for this planet? This could very well be possible, because the synodic cycle of venus corresponds most closely to 6 rounds of 97 or 98 stones, as we have been able to see.

But also the synodic cycle of mars can be tracked with both counting systems very accurately, see tables. So I think our closest neighboring planets were followed very well with this system.

For our planets mercury, jupiter and saturn, the two stone circles are less accurate. I have to say this in all honesty. Nevertheless, I believe it is quite possible that both counting systems could have been used to record the synodic cycle of all visible planets. This can be done quite simply by counting the difference in stones and days forwards or backwards in the first round, as I have already explained.

On average, there is a difference of +/- 9 days with the reality of these five planets. If we made a circle of 96 or 99 stones, the average difference would suddenly be 12 days and that is 1/3 more. It is therefore very remarkable that the number of stones used at Avebury (98) and Newgrange (97) comes closest to reality.

But Newgrange does not stand alone! On either side in the Boyne-valley lies the same kind of mound (Dowth and Knowth) wich are also marked with kerbstones. On one side, the mound of Dowth is enclosed with an estimated 115 or 116 kerbstones, because half of the stones have disappeared. This is exactly the average synodic cycle of mercury (116), the innermost visible planet of our solar system.

On the other side, the mound of Knowth is marked with 127 kerbstones. Three rounds makes 3 x 127 = 381 stones/days. That only differs three days with the average synodic cycle of saturn (378), the outer visible planet of our solar system.

As I have already indicated, the difference in days with the counting stones of Newgrange and Avebury is the largest with these two planets. Could that be the reason why the builders have chosen to represent these cycles in the Dowth and Knowth kerbstones?

Finally, I would like to add one more point about Newgrange as an additional contribution to my theory. In front of the entrance of the dolmen with mound is a beautifully decorated kerbstone resting, see drawing ‘The Entrance Stone’. On the front of this stone, five complete spirals are notched. I believe these spirals represent the five planets what this article is about.

The two spirals on the right turn the other way around than the three on the left and they seem to be separated from each other. The two spirals on the right could represent the inner planets (rotate between sun and earth) mercury and venus. The three spirals on the left the outer planets mars, jupiter and saturn. Isn’t it all wonderful!?!

Peter van den Hoek

Nieuwstraat 22 D

3811 JZ Amersfoort


Noot:1. https://www.youtube.com/watch?v=Fq516VKysw8


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