Saša Caval / Tomaž Podobikar / Ivan Šprajc

(Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia)

Archaeo-astronomy is a sub-science of archaeology that can be applied to almost all archaeological periods, exploring the important connections between cultures and astronomical events that are reflected in their architecture. Previously, such research has been used to examine the orientations of early mediaeval graves in Slovenia.
Following research carried out in other European countries (including Italy, Croatia, Hungary, Spain, France and Germany), we conducted a research project to study the astronomical orientations of Romanesque churches in Slovenia. Prior research had found that early Christian churches, including those of the Romanesque period, were aligned toward saints, main natural feasts and to the main feasts of important church representatives or orders. Computer simulations were employed to model and examine possible relationships between astronomical events and archaeological sites or structures. We used digital recordings of all Romanesque churches, made by the Surveying and Mapping Authority of the Republic of Slovenia, and computer programs to calculate the historical declination of the sun to compare structural orientations with the positioning of the sun. We converted our data into calendar dates, subtract the days difference between Gregorian and Julian calendar (in Romanesque period they were still using the Julian calendar), in order to compare the orientations of the churches in our study at the time of their construction.
In checking the accuracy of the survey information obtained from the Surveying and Mapping Authority (we manually surveyed 25% of the churches in our sample), we discovered many inaccuracies in the measurements supplied (with alignment variations of up to 3°). The imprecision of the survey information was a problem for our study, but the large sample size allowed us to extract useful information and with additional fieldwork, we managed to eliminate most of the errors and yield invaluable information about the manifestation of mediaeval beliefs in their architecture.