Father Antoine Thomas and the Birth of ‘Modern Astronomy’ in Thailand

‘Modern astronomy’ was introduced to Siam (present-day Thailand) when the Belgian Jesuit missionary-astronomer Father Antoine Thomas carried out astronomical observations in 1681 and 1682 in order to determine the latitude and longitude of Ayutthaya. Three years later a contingent of French Jesuit missionary astronomers observed a total lunar eclipse from Lop Buri, which marked the start of an intensive two-and-a-half year period of observational activity at Lop Buri under the sponsorship of King Narai. This ended only with King Narai’s premature death in July 1688, and Western missionary-astronomers were then expelled from Siam.