Which moon phase marks the first day of Chinese New Year?

The first day of Chinese New Year falls on a new moon.

Chinese New Year begins on the first day of the first month in the traditional Chinese lunisolar calendar. Astronomically, that day is tied to the new moon, when the Moon’s Earth-facing side is not illuminated by direct sunlight. The holiday therefore moves through the Gregorian calendar each year, usually occurring between January 21 and February 20.

The date is not simply the first new moon after January 1. Chinese calendar rules generally place New Year on the second new moon after the winter solstice, though an intercalary month can affect the calculation. This is why the celebration may begin in late January or February. The Lantern Festival follows on the 15th day of the first lunar month, around the first full moon of the new year.