Astronomical significance of architectural orientations in the Maya Lowlands: A statistical approach

A recently accomplished systematic study of 271 architectural orientations measured at 87 archaeological sites in the Maya Lowlands led to several conclusions about the underlying astronomical motives. In order to test these proposals, we have performed a number of statistical analyses, employing kernel density estimations (KDEs) and cluster analyses without preconceived ideas on the directionality of the different buildings. Since most buildings have roughly rectangular ground plans, both north-south and east-west orientation axes were analyzed. Our KDE analyses, in which the errors assigned to alignment data were considered, are based on the assumption that the direction in which a particular orientation group was astronomically functional is indicated in histograms by narrower maxima with larger amplitudes. The distribution of azimuths and declinations suggests that the orientations were functional predominantly in the east-west direction, largely referring to the Sun, but the existence of alignments to the major extremes of Venus and the Moon on the horizon is also highly likely. The analyses of the distribution of sunrise and sunset dates corresponding to solar orientations, as well as of the intervening intervals, support the idea that the orientations recorded the dates separated by multiples of 13 and 20 days, allowing the use of easily manageable observational calendars intended to facilitate a proper scheduling of agricultural activities and the associated rituals. As revealed by cluster analyses, the East Coast and the Usumacinta basin share similar orientation trends, which are, however, notably different from those in the rest of the Maya Lowlands, probably reflecting regional variations observed also in other cultural elements.