The Sirius Eclipse: Precessional Invisibility of Sirius from Northern Latitudes and the Pre-Sirius Phase of Sacred Architecture (c.13000–7000 BCE)

Sirius (α Canis Majoris) undergoes a multi-millennial precessional arc during which its declination drifts far enough south to render it invisible from the northern Mediterranean latitude band. Epoch-corrected calculation shows that Sirius reached its precessional minimum declination of approximately −60.1° at approximately 11,820 BCE — at which point the star was invisible from all latitudes above approximately 30°N. From this minimum it has been drifting northward ever since, re-crossing the horizon thresholds of successive latitude bands in a sequence whose dates are calculable with precision. This paper presents that sequence, defines it as the ‘Sirius eclipse’, and proposes a framework — the pre-Sirius phase — for interpreting sacred architecture built during or immediately after the eclipse at latitudes where Sirius was recently absent or newly returned. Three consequences follow. First, any monument at latitude ≥37°N built before approximately 9,200 BCE is a pre-Sirius monument regardless of its other astronomical encodings. Second, monuments at Levantine latitudes (32–34°N) built before approximately 8,000 BCE similarly could not encode Sirius as a contemporary alignment target; orientations at these sites encoding Sirius’s rising direction necessarily encode an ancestral bearing from the pre-eclipse epoch. Third, the re-emergence of Sirius at each latitude band marks a horizon — the moment at which the tradition’s primary calibration star became available again — that is encoded in the site record. Göbekli Tepe (37.22°N, c.9500 BCE) is identified as the defining pre-Sirius monument. The Trilithon of Baalbek (34.00°N) is identified as an ancestral-bearing monument whose 135° axis encodes Sirius’s position at approximately 6,035 BCE, within the post-eclipse re-emergence window at that latitude.