Portugal’s 6,000-year old prehistoric tombs possibly served as astronomical ‘telescopes’


When it comes to the antediluvian scope of 6000-year-old passage graves in Portugal, there was possibly more to the ritualistic side of affairs than just providing a resting place for the dead. According to researchers at the University of Wales Trinity Saint David, the elongated ambit of these tombs may have served as some form of astronomical ‘tool’ that rather aided in observing the stars more clearly. More specifically, the structural orientation of the complex suggests that the tombs were aligned to enhance the view of Aldebaran, the red star (and the brightest one) of the Taurus constellation.

Now it should be noted that from the historical perspective, the study of astronomy and stars had more to do with their cyclical scope that corresponded to our earthly calendars. Simply put, many of our ancestors recorded the movement of stars so as to mark their timetable based on approaching seasons. For example, in the case of the Aldebaran, the star’s first appearance (each year) during early morning could have heralded the start of summer when the ancient folks moved their flocks to the suitable grazing grounds above mountains. As Dr Fabio Silva of the University of Wales Trinity Saint David, made it clear –

This first rising of Aldebaran occurred at the end of April or beginning of May 6,000 years ago, so it would be a very good, very precise calendrical marker for them to know when it was time to move into the higher grounds.

But the question still remains – how can ancient 6,000-year old tombs work as rudimentary astronomical telescopes? Well according to the researchers, the corridors present inside these rooms were possibly oriented and shaped to allow a glimpse of the rising red star. In other words, their spatial characteristics allude to a tunnel vision effect with the small entrances (at one end of the corridors) acting as windows that open into the horizon. So from the optical perspective, the viewer’s attention could have been focused on these entrances/windows, while the side walls would block out the ‘distracting’ effects of early sunlight and other external conditions. Furthermore, since such scenarios took place in late-night/early-morning phases, the viewer’s eye would have been accustomed to the darkness inside the tomb. This in turn possibly enhanced the person’s capacity to discern some faint light from a distant star through a strategically placed (entrance) opening – thus turning the tombs into telescopes without lenses.


But of course, all of these factors still fall in the category of hypothesis, as opposed to proven facts that entail ancient ‘telescopes’. To that end, the researchers are looking forth to try out pertinent experiments on actual live subjects (viewers) from inside these prehistoric tombs. As Silva said –

We are going to simulate this star rising at twilight conditions and allow people to tell us when they can see it. Then [we will] compare that with a control group of people that are in a room which would replicate the conditions of being outside the passage grave.

Dr Marek Kukula, public astronomer at the Royal Observatory Greenwich, further added –

As any archaeologist will tell you, trying to understand what was going through the minds of the people who built these prehistoric monuments is a difficult task. But this team is carrying out a fascinating study into how the human visual perception of a small patch of sky can be affected by the narrow views along the passages of the Portuguese structures.


The study was originally presented at the Royal Astronomical Society’s National Astronomy Meeting at the University of Nottingham.

Source: TheGuardian / All Images Credit: University of Wales Trinity Saint David/Nottingham Trent University

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