The light of the Pillirina

• Circular aperture in the vault of the cave, with edges that appear worked.
• Patch of light projected onto the water and the floor, its position varying over the day and over the year.
• Photographs taken on 21 June 2026, close to the summer solstice.

• Diameter and height of the aperture relative to the water surface.
• Aperture–water–floor geometry: distances and angles.
• Position of the patch of light at the hours of survey.
• Reference sea level at the time of the measurements.

A solar model reconstructs the path of the patch of light over the year from the measured geometry. A lunar model does the same for the Moon, whose declination oscillates over a cycle of about 18.6 years: this produces configurations that recur with their own periodicity and that may leave a recognisable signature.

• The hypothesis of a lunar signature bound to the position of the patch of light in particular configurations of the lunar cycle.
• The artificial nature, total or partial, of the working of the aperture.
• The chronology of any human intervention.
• Any ritual, calendrical or observational function.

• A geological assessment attributing the aperture entirely to karst processes or to natural collapse.
• A reconstruction of sea level that, at the epochs compatible with human occupation, would make the cave inaccessible or completely submerged.
• A topographic survey contradicting the aperture–water–floor geometry described here.
• The absence of any evidence of human occupation in the deposits.

• Archaeological verification: test trenches and analysis of the deposits, with the competent authorisations.
• Geological verification: an assessment of the genesis of the aperture and of the traces of working.
• Topographic verification: independent instrumental survey of the cavity and of the aperture.
• Direct observation on the dates predicted by the solar and lunar models.