Astronomical expert： February 3 rd in beginning of spring is very rare. The last time it happened was 120 years ago.

　　Xinhua News Agency, Tianjin, February 2 (Reporter Zhou Runjian) beginning of spring is the first of the 24 solar terms in the lunar calendar. In many people’s impression, February 4th is usually the right day in beginning of spring, but this year it is February 3rd in beginning of spring. Astronomical experts said that the 3rd beginning of spring is rare, the last time happened in 1897, 120 years ago, and the next time happened in 2021.

　　It is understood that 24 solar terms is divided according to the position of the sun on the ecliptic (that is, the earth’s orbit around the sun). Depending on the sun starting from vernal equinox (longitude zero, at this moment the sun shines vertically on the equator), every 15 degrees forward is a solar term; After running for a week, I returned to vernal equinox, which is a tropical year, which is 360 degrees, so it is divided into 24 solar terms.

　　Shi Zhicheng, a member of Chinese Astronomical Society and director of Tianjin Astronomical Society, said that the length of a tropical year is 365.2422 days, so the average time period of each solar term in the Gregorian calendar year is about 15.25 days, and its starting date is generally fixed. However, the annual apparent motion of the sun is not uniform, and the length of the calendar year is also different, with 365 days in a normal year and 366 days in a leap year, so the specific time of solar terms will change slightly.

　　For the same solar term, every year is 6 hours or 5 hours behind the previous year, and in leap years, it is 24 hours ahead of schedule. In this way, the reflection on the date is that the same solar term remains unchanged or lags behind by one day in the normal year and the previous year; In leap year, it remains the same as the previous year or one day earlier. In this way, the starting point of the same solar term has three different Gregorian calendar dates. Take beginning of spring as an example, there are three situations: 3 February, 4 February and 5 February.

　　Shi Zhicheng said that the statistics from 1900 to 2000 showed that there were only February 4th and February 5th in beginning of spring, but there was no February 3rd, while the statistics from this century showed that there were only February 3rd and February 4th, but there was no February 5th in beginning of spring.

　　"According to the astronomical almanac, beginning of spring is the most common on the 4th. Although beginning of spring on the 3 rd or 5 th is rare, it is also a normal calendar phenomenon, and the public should face it with a normal heart. " Shi Zhicheng stressed.