Chinese New Year always starts on a new moon, when the Moon is between the Earth and Sun and it looks all dark in the night sky. Because new moons happen about every 29.53 days but the year set by Pope GregoryXIII is 365.2425 days long, the Chinese holiday moves to different days each year. The Chinese calendar adds a 13th month every so often to keep the seasons in the right place, so the first day of the new year always happens between January21 and February20 on the 2nd or 3rd new moon after the 1st day of winter. The chart on the right gives the day of each Chinese New Year from 1996 to 2031.