Thai astrology has a color of the day for each day of the week. The color is based on the color of the God who protects the day or Navagraha. For example, the God of Sunday is Surya which has as the red color. These colors of the day are the traditional Thai birthday colors. For example, King Bhumibol Adulyadej was born on Monday, so on his birthday places in Thailand will be decorated with the color yellow.