Why is my birthday 19880507 (solar calendar) not the same day as the lunar calendar after19 years?

Calendar based on the apparent movement of the sun, referred to as "solar calendar" or "solar calendar"; lunar orbit

A calendar based on the apparent movement law of the moon is called "Lunar Calendar" or "Lunar Calendar" for short. 【 1 】 Lunar calendar, one of the traditional calendars in China, is also called lunar calendar, lunar calendar, ancient calendar, yellow calendar, summer calendar and old calendar. The lunar calendar determines the moon according to the law of its movement: the orbit of the moon is called the white road, and both the white road and the ecliptic are two great circles on the celestial body, which intersect at five degrees and nine minutes. The moon goes around the earth and appears on the ecliptic twice, which lasts for 7 hours and 43 minutes 1 1.5 seconds on the 27th, and is called "Stellar Moon". Only when the moon revolves around the earth, the position of the earth also changes. The forward count is more than 27 degrees, and the moon runs 13 degrees 15 minutes every day, so it takes 12: 44: 2.8 to return to the moon on the 29th, which is called "the first moon", and it is called the moon according to customs, which means the first moon.

The basis of the lunar calendar is the year of the tropic of Capricorn and the first month. The tropic year is the time required for the sun to pass through vernal equinox twice in a row, that is, 365.2422 days (365 days, 5 hours, 48 minutes and 46 seconds). "The first month of the lunar calendar" is the time between two consecutive new moons (new moons) or two full moons (full moons), that is, 29.5306 days (June 29th 12 hours, 44 minutes and 3 seconds).

Because 12 "Wang Shuoyue" is only 354.3672 days, which is more than 10 days different from 365.2422 days in the tropic year, this difference adds up to a leap month. As early as the Spring and Autumn Period in 5600 BC, the calendar of China adopted the arrangement of seven leap months in nineteen years.

19 years later, the solar calendar and the lunar calendar you mentioned are not one day, which is the difference. It is not easy for our ancestors to determine the time, that is, the new calendar is in February, sometimes with 29 days and sometimes with 28 days.