Who invented the calendar? Why do the calendars for the same year have different dates? Who made up the calendar every year?

In the world, China was one of the first countries to invent the calendar, and its emergence had a certain impact on the development of China's economy and culture. The lunar calendar, one of the traditional Chinese calendars, is also known as the "lunar calendar", the "Yin calendar", the "ancient calendar", the "yellow calendar", the "summer calendar" and the "old calendar". The Lunar Calendar is a combination of Yin and Yang calendars. On the one hand, the lunar orbit around the earth is one "month", and the average length of the month is equal to the "lunar month", which is the same as the principle of the Lunar Calendar, so it is also called the "Lunar Calendar"; on the other hand, it sets up the "intercalary month" in order to make the average length of each year as close to the year of return as possible, and at the same time it sets up the twenty-four Solar Terms in order to reflect the characteristics of the changes of the seasons, so the Lunar Calendar combines the characteristics of the Lunar and Yang Calendars, and it is also known as the "Lunar and Yang Calendars". It is also known as the "yin-yang calendar". Almost all Chinese people around the world, as well as in countries such as the Korean Peninsula and Vietnam, still use the Lunar Calendar for traditional festivals such as the Spring Festival, the Mid-Autumn Festival and the Dragon Boat Festival. The wise Chinese invented the calendar and the festivals through years of labor. Legend has it that a long time ago, there was a young man named Wannian who, one day, while going up the mountain to cut firewood, sat down to rest in the shade of a tree because it was too hot in the sun. Suddenly, the movement of the shadows on the ground inspired him. After returning home, he spent several days and nights designing a sundial to measure the sun's shadow and count the time of day. However, when it was cloudy, rainy or foggy, the sun was not shining, and the measurements were not good enough. Later, the dripping spring on the cliff aroused his interest, and he made a five-tier funnel. Over time, he realized that the length of the day would repeat itself every 360 days or so. The king of the country at that time was called Zuyi, and the unpredictability of the weather also made him very upset. When Wannian heard about this, he took the sundial and the funnel to the king and told him the reason why the sun and the moon were running. Zu Yi was very happy to hear this, and thought it was very reasonable. He left Wannian behind and built the Sun and Moon Pavilion in front of the Temple of Heaven, the Sundial Terrace and the Leaky Pot Pavilion. Zu Yi said to Wannian, "I hope you can measure the sun and moon, calculate the exact time of morning and evening, and create a calendar for the benefit of the people of the world." Winter and spring came and went, year after year. Later, Wannian, after a long period of observation and careful calculation, formulated an accurate solar calendar. When he presented the solar calendar to the succeeding king, he was already covered with a silver beard. The king was so impressed that he named the solar calendar "Wannian Calendar" in honor of Wannian's achievement, and named Wannian the Longevity Star of the Sun and Moon. The Chinese calendar was formed by the year, month, and day based on the cycles of the sun, the moon, and the earth, as well as the laws of nature and the four seasons of spring, summer, fall, and winter. In ancient China, there were three types of calendars, the solar calendar, the lunar calendar and the combined lunar and solar calendar. The solar calendar is also known as the solar calendar; the lunar calendar is also known as the Taiyin calendar and the lunar calendar; and the yin-yang combined calendar, which is commonly known as the lunar calendar. The yin-yang calendar has been used until today. Why has the lunar calendar been used until today? In today's view, the creation of the calendar was the result of the ancient Chinese people's long-term observation of the astronomical operations in order to grasp the time of agricultural work (referred to as the agricultural time). The Chinese lunar calendar is called the "yin-yang" calendar because it has not only the elements of the solar calendar, but also the elements of the lunar calendar. It combines the rules of the sun and the moon into a single calendar, making an end of the influence of both on agriculture, so the Chinese lunar calendar is more practical and convenient than the purely lunar calendar or the solar calendar commonly utilized in the West. The lunar calendar is one of the representatives of traditional Chinese culture and is often regarded as a source of pride by the Chinese for its accuracy and ingenuity. Why there are two Julys in a year in China's lunar calendar? According to astronomical experts, the Chinese lunar calendar is a yin and yang calendar, and is written using the "19-year, 7-leap method". "Nineteen years, seven leap method" that is, in the 19 lunar years, the provisions of 12 flat years, 12 months a year; the other seven years each year, an additional month, to become 13 months, this increase in the number of months will be called "leap month