Thai Wisdom of Thum–Mong and the Moon Phases From Thai Lunar Calendar (KHUEN–RAEM): The Tool for Easily Computing the Accurate Time of Moon Rise and Moon Set in Thailand

Abstract

The Sun rise and The Sun set are normally at the same time each day, but not for the Moon rise and the Moon set. The Moon rises at 48-52 minutes lately each day, so it is very difficult to predict the time for the Moon rise on the day concerned; but with the Thai wisdom, Thai people in the old days had the knowledge of how to predict the time for the Moon rise i.e. by calculating the exact time for the Moon rise each day. They used the constant number of 8 to multiply with the number of the day according to the Moon phase at each day, in the Lunar Calendar, that the result of the Moon rises (interpreted from the result at the first digit or at the first and second digits) be at the “Mong - Hour” for the day on the first fifteen days of the Lunar phases and be at the “Thum - Hour” for the night on last fifteen days of the Moon phases with which the last digit of the result must be the “Baht” that was multiplied by 6 to be “the minute” in the present time. The result calculated is so accurately that the Moon rises not different more than 1 hour and a quarter when compared with the result calculated by the Thailand Astronomical Society. Furthermore, the time for the Moon set is approximately 12 hours from the time of the Moon rise each day. So, it should be studied and used efficiently by historian students for understanding the situations in the past that were involving the lunar calendar, and by the tourist guides that they could lead the tourists well in the field of the dark sky for the star gazing party at night or for travelling in the national park at night up country; and this knowledge should be preserved as a Thai national heritage for the next generations as well