Do any numbers in between 80 and 85 (or thereabouts) hold any relatively important or relatively obvious meaning in ancient astronomy ?

A few clarifications:

  • By ancient I mean related to human antiquity. (Thus, for instance, although in modern times there are indeed 88 known constellations, almost half of them were unfortunately unknown to the ancients).

  • The meaning in question could refer, for instance, to the number of time periods in a specific time cycle, or to the number of stars in a certain constellation, etc.

  • By relatively important or relatively obvious I mean something as self-evident and meaningful to an ancient sage as the fact that there are roughly 360 days a year, or that the number of constellations in the northern and southern hemispheres are 21 and 15, respectively (as known to the ancient Greeks, for instance).

Some background information:

About a century ago, an archaeological site, located in a clearing in the woods, and dating back to the first two centuries BC, was discovered at 45.62°N and 23.31°E, at an altitude of roughly 1,000 meters.

The structure, oriented on a NNW-SSE axis, consists of four concentric circles, the second and fourth of which (counted from the exterior towards the interior) have a clear calendrical and astronomical interpretation, pointing to a semester of 180 days, divided into exactly six months of thirty days each, and to a number of 21 + 13 constellations in the boreal and austral hemispheres, comparable to the figure given by the astronomer Claudius Ptolemy in his famous Almagest. I was wondering whether the third circle, consisting of a number of no less than 82, and no more than 84 pillars, might not also have a similar meaning. Now, don't get me wrong, interpretations abound, but most of them tend to be either slightly forced, or are outright pseudo-science.

As an interesting aside, there were, initially, only 68 pillars still standing, which just so happened to be double the number of those which constitute the inner horseshoe (as it is called), making many archaeologists speculate that its builders were aware of the fact that after 68 semesters of 180 days, corresponding to a number of 21 + 13 = 34 years of 360 days, the calendrical error would amount to almost an entire semester. All nice and tidy, but this proposed solution suffered a devastating blow when further excavations, performed by the son of the man who initially discovered the site (both were historians by profession) revealed that the number of pillars comprising the third circle was much higher than previously thought. Furthermore, a certain scientist has already started speculating that the number of elements should be about 84 long before the excavation in question even happened in the first place! (He based his ideas on the fact that if the second circle represents the solar year, and the fourth one basically corrects it, then there should also be a refinement to the nice-but-inaccurate 30 day month as well). However, even this little gem of a theory has a small and insignificant scratch: One of the main reasons why 84 year lunar cycles were even considered in the first place was because its value is a multiple of 28, the latter representing the number of years in a perpetual calendar synchronizing the seven day week to the solar cycle... Just one minor glitch, though: The civilization that built the structure had months of thirty days, divided into five six-day weeks, as is evidenced by the clear and uniform distribution of the pillars forming the second circle. (Certainly, it is not completely impossible for them to have borrowed such a time-correcting mechanism from other neighboring cultures, but it's not highly likely either). So, herein lies the dilemma...

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    $\begingroup$ Impossible to answer. You may as well take every stone circle, etc. in the world, count its number of stones, pillars or posts, and try to find an astronomical reason for every number. $\endgroup$
    – Andy
    Sep 8, 2016 at 6:28
  • $\begingroup$ @Andy: Almost all competent authorities involved in the study of said structure (from historians and anthropologists to mathematicians and engineers) agree that it serves calendric and astronomic functions, which is especially evident from the arrangement of the pillars forming the second and fourth circles. So no, this is not a wild goose chase. $\endgroup$
    – Lucian
    Sep 8, 2016 at 7:49
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    $\begingroup$ @Andy: Though many wooden pillars have indeed been reconstructed, their foundations, as well as the various pathway gaps, are made of stone, and have always been part of the site's historical pattern. $\endgroup$
    – Lucian
    Sep 8, 2016 at 10:15
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    $\begingroup$ What you're really asking (or should be) is whether the number has significance to the culture that built the structure. If, for example, the number 83 had some significance to the ancient Olmecs in Mexico and Guatemala, the fact that you're talking about a monument in Romania would certainly be relevant. You should mention the age and location of the monument in the question rather than dribbling out information a bit at a time in the comments. en.wikipedia.org/wiki/Sarmizegetusa_Regia $\endgroup$ Sep 8, 2016 at 15:03
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    $\begingroup$ "* ... although in modern times there are indeed 88 known constellations ...*" -- Constellations are invented, not discovered. "45.62°N and 23.31°E" -- You don't feel the need to mention where in the world that is? "The civilization that build the structure ..." -- And you don't say anything about that civilization. If nothing is known about the culture, you could at least say so in the question. According to Wikipedia, they were called the Dacians; why not mention that? $\endgroup$ Sep 14, 2016 at 20:00

1 Answer 1


The site to which you are referring is Sarmisegetusa in old Dacia, which was a well known royal citadel of the Illyrians in Roman times.

Sarmisegetusa was a fortress, not an observatory. The reconstructed posts there were used to hold up ceilings and walls.

Sarmisegetusa backs up against face of the mountain, so half of the horizon cannot even be seen from the site. That fact alone excludes the possibility that anyone was doing any astronomy there.

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    $\begingroup$ This is a good answer. It would be better with a few sources to back up the claims. $\endgroup$
    – James K
    Mar 3, 2018 at 20:29
  • $\begingroup$ Though perhaps not an actual observatory, the site in question is strongly believed by archaeologists to have been an important sanctuary inside the main citadel, so astronomical symbolism is certainly not excluded, even if no astronomical observation might have ever been performed there at all. $\endgroup$
    – Lucian
    Jun 12, 2018 at 18:13
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    $\begingroup$ I'd like to up vote your answer but I can't until I see some evidence that it's based in fact. Why not include a link to a supporting source for your assertion? $\endgroup$
    – uhoh
    Jul 19, 2018 at 1:32
  • $\begingroup$ Dacian Fortresses and Sarmizegetusa Regia are located there. A Google Translation of the second link says: Fort, Temple and Roman bath. That's it. $\endgroup$
    – Rob
    Jul 20, 2018 at 16:11

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