ILLUMINATION EFFECTS IN CELANOVA AND AGÜERO SPANISH MEDIEVAL CHURCHES

An aspect of undoubted interest in the study of Romanesque architecture refers to illumination effects, when the sunbeams mark significant points in a church. But these lighting effects can be accidental. Any opening or hole would allow the entry of a sunbeams that could unintentionally illuminate a certain element, some day of the year. The objective of this article is to establish reasonable conditions to distinguish casual phenomena from premeditated ones. The methodology used for the study of solar trajectories and the calculation of the dates and times of the sunbeams incidence at a given point, is based on the use of solar charts. It is a simple, effective and precise method that can be used in further studies carried out even by researchers with basic knowledge of astronomy. A very simple construction method has also been analysed with the elements avail-able to a medieval builder, which has made it possible to analyse the different solar orientations and to be able to distinguish lighting effects that have been deliberately projected from purely accidental ones. This method-ology has been applied to two notable Spanish buildings: The Mozarabic chapel of Celanova (Ourense, Spain) as an example of a questionable solar phenomenon and the Romanesque church of Agüero (Huesca (Spain) as an example of a demonstrable phenomenon. This article may be a useful contribution for the study of these phenomena and to analyse their intentionality and the way in which they could have been projected by their builders.