World’s Largest Dolmen as Moon- and Sundial

Entrance of the Dolmen de Menga

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

In the Southern Spanish town of Antequera (Málaga) you can find a Dolmen made up of huge stones. The heaviest stone is a capstone that weighs no less than 180 tons.  This is more than four times the weight of the heaviest stone used at the well-known Stonehenge¹.   The structure that consists of a passage and room, see drawing Dolmen de Menga, is no less than 27,5 meters long, and the room measures up to 6 meters at its widest. In this room, three pillars are placed to wear the enormous weight of the capstones.

In the literature on this dolmen is described that it is aligned to a rock massif in the form of a human head called ‘Pena de los Enamorados’ (Rock of the Lovers) and to the Sunrise during Midsummer.

This last claim caught my attention, because looking at this dolmen, a Moon alignment seems more obvious at first than a Sun alignment. Reason enough for me to dive a little deeper into it as an Archaeoastronomer. This is an expensive word for someone who studies Archaeology from an Astronomical point of view, so Sun, Moon and Stars.

Indeed, this dolmen seems to have a very convincing alignment to the Moon, but the Sun also plays a significant role in this. The right side of the dolmen seems to act as a huge Moon- and Sundial! In this article, I’m going to try to explain how I see this:

When the Moon makes its longest orbit along the sky, it shines on the entire right wall of the dolmen during its rise. Her shadow begins exactly on the separation of stone B (Backstone) which marks the back wall and stone R1 (Right 1) which marks the beginning of the right wall, see drawing Dolmen de Menga. I don’t believe that this exact alignment is based on pure coincidence. This must have been done consciously by the builders some 5.500 years ago with a precision that really commands an incredible amount of respect. How exactly did they do it with such heavy stones?

When the Sun in turn makes its longest orbit along the sky with Midsummer, it shines during rise to the middle of the right chamber wall. His shadow begins on the separation of stone R4 and R5. Could that also be the reason why stone R4 jumps forward a little? I think so!

Unlike the Sun, the longest Moon orbit is not constant. With an average interval of 9,3 years, her light moves from the point between stone B and R1 (Major Lunar Standstill) to the point between stone R7 and R8 (Minor Lunar Standstill). To accentuate this alignment, stone R7 also jumps forward, with which this stone also marks the beginning of the room. How precisely did the builders have done this?

The Sun is easier to fathom than the Moon. Every year his light shines by rise during Midsummer around june 21 for about 10 days to the middle of the right chamber wall.  I can well imagine that the Dolmen Builders or Megalithic Culture honored this annual moment with a feast or celebration.

The Moon, as mentioned, does not have such a fixed position, but shines her light during rise on the right chamber wall from the beginning stone R7 (Minor Lunar Standstill) to the end stone R1 (Major Lunar Standstill). This event takes place within 9 to 9,5 years. Because the Moonlight is much weaker than the Sunlight, this can only be observed in the autumn, because the Moon then rises in its Standstill position at night. Fortunately, a Minor or Major Lunar Standstill lasts up to 1,5 to 2 years, which means that it can always be observed in the autumn, even if the exact moment takes place in the spring.

Inside the Dolmen de Menga

I can also very well imagine that especially a Major Lunar Standstill, at which the Moonlight of the rising Moon shines on the entire right wall to the back of the room was celebrated Grandly.

Has now everything been said about Dolmen de Menga? No, there’s more to come! Lunar Standstills always go hand in hand with eclipses of Sun and Moon. When the Moon rises in one of her extreme Standstill positions (Minor or Major), eclipses always take place in spring and autumn. If her rise is exactly in between, like the Sun with Midsummer, eclipses take place in summer and winter. In this way, these Dolmen Builders could also predict eclipses. How special is that!

Now we are not there with the whole story, because the stones in the passage also have a function as Moon- and Sundial! Just as the Sun makes its longest orbit along the sky during Midsummer, it makes its shortest orbit during Midwinter. This event has also been recorded by the builders in this dolmen, because at that moment the Sun shines only on the first part of stone R11 to the right side of the entrance during its rise.

Like the Sun, the Moon also makes her shortest orbit along the sky, but unlike the Sun every month and two weeks after her longest orbit. We call this the Minimum (Min.), as we refer to its longest orbit with the Maximum (Max.), see drawing Dolmen de Menga. When the Moon rises during her Minimum, she illuminates only the first stone R11 of the passage on the right side of the dolmen, like the Sun does during his shortest orbit. During a Minor Lunar Standstill, her light shines on the middle of this stone and during a Major Lunar Standstill on the first quarter of it. This means, in theory, that during a Major Standstill in a period of two weeks, the Moon moves her light over the entire right wall of the dolmen from the first stone R1 to the last stone R11. And then back in a complete cycle of 27 to 28 days.

I say:  ‘in theory’, because in practice the first half can only be seen in the autumn and the second half in the spring, because the Sun with his bright light will always claim the dolmen to be able to follow the whole cycle in one month. If you want to experience the spectacle for half, travel to Dolmen de Menga from 8 to 15 september 2025. Then you can see the Moonlight moving daily along the entire right wall of the room to the very back. What a beautiful daily light show that must be!

My comment ‘in theory’ also refers to half of this spectacle in the spring. In reality, this is not quite as I have described. This is because the entrance to the dolmen has been ruined. At least I believe so. I think that the very first capstone of the original dolmen is missing. In the drawing I indicated it with a dashed line. The supporting stones (R11/L10/L11) are still there, but half broken.

I believe that the precise alignment of this dolmen to Sun and Moon seems to help me with this conviction. Just look at how all the alignments in the drawing seem to be so accurate from the original design. Now the Sun and Moonlight shines into the dolmen from half of the broken stone L10, making all alignments seem to be much less accurate. From this I can only conclude that the original dolmen looked most like the floor plan I added. In this way, Astronomy can help us to reconstruct the original plan of such Archaeological Buildings.

Dolmens of this type (Passage Dolmens) are generally aligned in such a way that the inward shining light of Sun or Moon during rise or fall illuminate the backstone(s). As an example, I mention the beautifully and richly decorated Gavrinis in Brittany (France). The two stones that are positioned in the back of the room are illuminated by the rising Moon during a Major Lunar Standstill.

I do have a suspicion why the builders of Dolmen de Menga chose a different alignment. In my opinion, this has to do with the pillars that support the heavy capstones. These pillars catch the light away from the Sun or Moon shining inwards, so that you would only have a narrow strip of light on both sides of the backstone, if the usual alignment for this type of dolmen have been used. The builders didn’t want this, so they just adapted the plan very skilfully. If you study the drawing carefully, you will see that the light of the rising Moon shines inwards exactly along the pillar P3 during a Major Lunar Standstill to the very back of the right corner. With what incredible precision this dolmen is built!



Peter van den Hoek

Nieuwstraat 22 D

3811 JZ Amersfoort

The Netherlands


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