  The Nabateans built several monuments in Petra and elsewhere displaying a
decoration with a preference for astronomical motifs, possibly as a reflection
of their religion. However, due to the lack of direct written accounts and the
scarcity of inscriptions we do not have a clear knowledge on the precise nature
of such believes and how these reflected on the calendar or the religious
time-keeping system of this ancient society. A statistical analysis of the
orientation of their sacred monuments demonstrates that astronomical
orientations were often part of an elaborated plan and possibly a trace of the
astral nature of Nabataean religion. Petra and other monuments in the ancient
Nabataean kingdom have proven to be marvellous laboratories of the interaction
between landscape features and astronomical events showing impressive
hierophanies on particular monuments related to cultic times and worships.
Among other findings, the famous Ad Deir has shown a fascinating ensemble of
light and shadow effects, perhaps connected with the bulk of Nabataean
mythology, while from the impressive Urn tomb, a series of suggestive
solstitial and equinoctial alignments emanate which might have lately helped
its selection as the cathedral of the city. This paper demonstrates that the
sky was a substantial element on Nabataean religion and reveals new evidence
for cultic worship centred on the celestial sphere.
