National Science Day is observed in Thailand every August 18, celebrating the anniversary of a total solar eclipse that occurred in 1868, which was predicted by King Mongkut two years earlier. King Mongkut, also known as Rama IV, is highly regarded in Thailand for his contributions to science, having studied astrology, astronomy, and mathematics during his monkhood. His achievements included reforming the official Buddhist calendar and predicting the solar eclipse, which is the focal point of this holiday. In 1982, he was declared the Father of Science in Thailand, leading to the establishment of National Science Day as an annual celebration. This day has since become one of the most significant public holidays in the Thai calendar.