The Great Cold, New Year's Eve and Spring Festival are "happily linked" only five times in this century!

Science Fiction Network, January 19 (Jin Kaiyi) The Lunar New Year is approaching, and some people have discovered that January 20 is the Great Cold, January 21 is New Year's Eve, and January 22 is the Spring Festival. These three days are "happily connected." Astronomy popularization experts said that in the 100 years of the 21st century, this coincidence has only occurred 5 times.

Why are these three days next to each other? Experts explain that the current 24 solar terms are determined by the position of the sun on the tropic ecliptic, that is, on a 360-degree circumference of the "ecliptic", it is divided into 24 equal parts. It is agreed that when the earth reaches zero degrees of ecliptic longitude, it is the spring equinox. Every 15 degrees is a solar term, starting from the beginning of spring and ending at the great cold. Most of their names come from agricultural production activities, climate and phenology in the Yellow River Basin of my country.

The lunar calendar is formulated according to the cycle of the moon phases and the tropical year. Each lunar phase change is one month, and the length of the solar year is taken as a reference. The 24 solar terms and the leap month are added to make the average calendar year compatible with the tropical year. Although the two follow different rules, they take each other into account and are related to each other. For example, the leap month of the lunar calendar is set according to the 24 solar terms.

The Great Cold solar term begins when the sun reaches 300 degrees of ecliptic longitude. Its date in the Gregorian calendar is basically fixed, usually on January 20 or 21, and on January 19 in very rare years. However, the dates of New Year's Eve and Spring Festival, which are adjacent to each other, are not fixed in the Gregorian calendar. As far as the 100 years of the 21st century are concerned, New Year's Eve will occur on any day between January 20 and February 18 in the Gregorian calendar. This also makes it uncommon for the Great Cold, New Year's Eve and Spring Festival to be "connected".

According to statistics, in the 21st century, there have been five coincidences of the Great Cold, New Year's Eve and Spring Festival, namely 2012, 2023, 2042, 2061 and 2080. In some years, the Great Cold and New Year's Eve even fall on the same day, such as 2004 and 2099. This is the result of the Chinese traditional calendar following the laws of the movement of the sun and the moon, and is a normal calendar phenomenon.