A solar term is one of the 24 points in traditional East Asian lunisolar calendars that matches a particular astronomical event or signifies some natural phenomenon. The points are spaced 15° apart along the ecliptic and are used by lunisolar calendars to stay synchronized with the seasons. Solar terms originated in China, and then spread to Korea, Vietnam, and Japan.
The (1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th 12th) solar terms in the above diagram are called Jit “". I have put an * next to it. There are total of 12 Jits representing 12 months. The starting of the Jit is the starting of the month.
So in Chinese Astrology Bazi Four Pillars of Destiny, solar terms, "Jit" is used as the cut off point for the year and month. For example, the first Jit, Start of Spring, is the starting point of the year. It is also the starting of the first Chinese month. The Start of Spring is normally falls on the 4/5th of February.
The Jit - "Start of Spring" is a special one. It has two functions. It is the starting point of a new Chinese year and the starting point of the first month of that year.
The Solar terms is corresponding to the lunisolar months. It is not hard to remember that the Chinese lunar month starts about one month and one week later than the western calendar month. For example, the first month in lunar calendar starts on the 4th or 5th in February. The second Chinese lunar month starts on the 5th or 6th in March. The third Chinese lunar month starts on the 4th or 5th in April and so on. Please refer to your 10000 years calendar or Tung Shu when your plotting a Chinese Astrology Bazi Four Pillars of Destiny Chart manually.
The correct year, month, day and birth hour is very important in constructing a Bazi Four Pillars of destiny chart.