As early as 2,500 years ago, about the Spring and Autumn Period
(770-476 BC), China had determined the point of Winter Solstice
by observing movements of the sun with a sundial. It is the
earliest of the 24 seasonal division points. The time will be
each December 21 or 22 according to the Gregorian calendar. The
Northern hemisphere on this day experiences the shortest daytime
and longest nighttime. After the Winter Solstice, days will
become longer and longer. As ancient Chinese thought, the yang,
or muscular, positive things will become stronger and stronger
after this day, so it should be celebrated. The Winter Solstice
became a festival during the Han Dynasty (206 BC-220 AD) and
thrived in the Tang and Song dynasties (618-1279). The Han
people regarded Winter Solstice as a "Winter Festival", so
officials would organize celebrating activities. On this day,
both officials and common people would have a rest. The army was
stationed in, frontier fortresses closed and business and
traveling stopped. Relatives a