On Yi Nationality New Year

Yi nationality people have two New Year in each year. This phenomenon originates from the primitive Yin and Yang ideals in the ten-month solar calendar traditional astronomy calendar for the nationality. The period from the first to the fifth month of each year is called Yang, the period from the sixth to the tenth month is Yin. The establishment of the calendar was based on the observations of the time length of the solar tropical year and the direction of the handle of the Big Dipper was used as a reference. Thus, in this calendar one year has ten months, each month has 36 days, the remaining 5 or 6 days of a year are arranged to be the New Year days. The precession of the equinox and the proper motion existed in the Dipper constellation are discussed in this paper and it is shown that we cannot determine the seasons accordingly using this calender. In the ten-month calendar, the summer Solstice and the Winter Solstice are used as the first day of the Yin and the Yang respectively, through the Observation of the time when the sun reaches the Tropic of the Cancer and the Tropic of the Capricorn. The winter New Year called Ten-Month Year has 4 remaining days and the summer New year called Torch Festival has 1 or 2 remaining days.