The winter solstice, also known as the short solstice, winter festival, sub-year-old, winter worship and so on, has both natural and humanistic connotations. It is not only an important solar term among the 24 solar terms, but also a traditional folk festival in China. The winter solstice is one of the four seasons and eight festivals, which is regarded as a big holiday in winter. In ancient times, there was a saying that the winter solstice was as big as a year, so the ancients called it "sub-year" or "off-year". The custom of winter solstice is different in content or detail because of different regions. In some areas along the southern coast of China, there is the custom of offering sacrifices to ancestors and feasting on the winter solstice. In the northern part of China, it is a custom to eat jiaozi every winter solstice.
Astronomical significance of winter solstice
According to modern astronomical science, on the winter solstice, the sun moves to 270 (the winter solstice point), and the position where the sun directly hits the ground reaches the southernmost point of the year. The sun almost directly hits the tropic of Capricorn (also known as the winter solstice line), and the sunlight is most inclined to the northern hemisphere. Therefore, the winter solstice is the shortest day and the longest night in the northern hemisphere, and the higher the latitude, the shorter the day and the longer the night.