Only four times this century! Why is February rare?

March 22 is Kui rabbit year leap February first. Astronomy science experts say that as a calendar phenomenon, February is relatively rare. In the 21st century, there have been four Februaries. Over the next few centuries, the frequency of Februaries declined, either once or twice, or not at all.

Yang Jing, member of the Chinese Astronomical Society and director of the Tianjin Astronomical Society, introduced that China’s current Gregorian calendar and the lunar calendar, the length of a Gregorian year is 365 days or 366 days, the length of a lunar year is 354 days or 355 days, the Gregorian year and the lunar year difference is about 11 days. “After years and months” will occur in the lunar year months and seasons do not correspond to each other, the phenomenon of cold and summer reversed.

In order to make the lunar year and the Gregorian calendar year can be basically corresponding, the lunar calendar adopts the method of “19 years and 7 leap months”, that is, in 19 years to arrange 7 leap months, the rules of placing leap months are determined according to the 24 solar terms. The 24 solar terms are the earth’s orbit around the sun, namely the ecliptic, divided into 24 parts at 15 degrees intervals, and then into 12 solar terms and 12 medium Qi, which are arranged alternately. According to the lunar calendar, each lunar month has a Zhongqi. If a month does not contain Zhongqi, the leap month of the previous month is considered as a leap month.

March 21 lunar February 30, is the spring equinox, the next middle-air grain rain on April 20 lunar March first, which March 22 to April 19 of the lunar month only one solar term Qingming, no middle-air, so this lunar month is a leap month. Since it precedes February, it is called February.

Why are there such months? “On average, a lunar month is 29.5306 days long, which is less than the interval between the two Zhongqi, so there must be a cumulative solar term without Zhongqi month.