Answer: Lunar Cycles

In the Western world, the New Year is rung in with fixed precision—at the exact moment the date changes from December 31st of one year to January 1st of the next year, per the Gregorian calendar, the New Year has arrived.

The Chinese New Year, however, is a different matter entirely and, while celebrated in proximity to the Western New Year, does not have a fixed calendar date. Instead, the Chinese New Year is determined by the lunar cycle.

Per tradition, the Chinese don’t herald in the New Year upon the first day of the Gregorian calendar, but by following the Chinese lunar calendar, which usually begins with the second new moon after the winter solstice (or the third new moon on rare occasions if an intercalary month intervenes). As such, the Chinese New Year can fall in a date range of anywhere from January 21st to February 20th. In 2014, for example, the New Year was January 31st, but in 2015 it was February 19th.