Archaeoastronomy investigates how ancient people used their knowledge of stars and the sky in their culture. It is necessarily multidisciplinary, encompassing astronomy, archaeology, anthropology, history, and statistics. Many civilisations used astronomy to build their most important structures. Stonehenge and Egypt’s Great Pyramid are prime examples of ancient monuments with astronomical associations. In Thailand, although east is the preferred direction for temples, many more are not perfectly aligned. Some are set to face the main transportation channels—a canal or a road. Yet there are those that turn toward seemingly arbitrary directions and have been dismissed as instances of primitive engineering.

The work of the History and Heritage of Astronomy Group at the National Astronomical Research Institute of Thailand (NARIT) has proven that assumption wrong. This lecture will tell you about the Group’s methodology and the results of their investigation in places like Prasat Phanomrung, Prasat Phimai, and Phrat That Doi Suthep. Their collaboration with BRIN, Indonesia’s National Research and Innovation Agency, yielded surprising results from Central Java’s World Heritage sites, including Borobudur, Prambanan and Candi Mendut.

The History and Heritage of Astronomy Group, based in Chiang Mai, has been working in many of Thailand’s important ancient monuments to find out whether there are any astronomical associations in those places. After a few initial scepticisms, their papers have been published in international journals and their reputation has meant that their field trips are always oversubscribed by local students.