Greek solar terms

The ancient Greek calendar is a kind of lunar calendar, with the summer solstice as the beginning of a year, and the summer solstice from the summer solstice to the next year as 1 year, while the month adopts a new moon [that is, 29.5306 days], the big month is 30 days, and the small month is 29 days, usually alternating in size, and there are also continuous big months, so1February is about 354 days. The vernal equinox period of the earth's revolution is the Tropic of Cancer. This periodic unit is based on the vernal equinox. In a tropical year, starting from the sun center, the center of the earth has arrived in vernal equinox twice in a row; Seen from the center of the earth, the sun center has reached the vernal equinox twice in a row. From the point of view of the geocentric celestial sphere, the length of a tropic year is the time interval when the sun center passes through vernal equinox twice in succession on the ecliptic. 1 tropical year =365.24220 days =365 days, 5 hours, 48 minutes and 45.5 seconds. The period from this new moon (or full moon) to the next new moon (or full moon) is the cycle of moon phase change, which is 29th 12 hours, 44 minutes and 2.8 seconds, that is, 29.5306 days, that is, the first month of the lunar calendar. In 433 BC, the Athenian astronomer Merton (5th century BC) put forward the method of setting 7 leap in 19 on the basis of actual measurement. In 19, he arranged 235 lunar months (including Dayue 125 and Xiaoyue 165438). The corresponding regression age is 365.2632 days, and the corresponding lunar month length is 29.5438+092 days. Meton publicized this jumping placement method at a Greek Olympic Games, which was widely appreciated and unanimously adopted. These figures are listed in the temple forehead, which is the so-called "golden number" in the name of beauty, and now it is usually called "meton Composition". Later, people gradually found that after a period of time (19), the appearance of the new moon was delayed by a quarter of a day, so in 334 BC, Kalibo proposed a new law. He took 19 as four times, that is, 76 years as a cycle, and the total number of days in this cycle was reduced by 1 day, that is, 125 BC. Hipacus found that the length of the tropical year and the lunar month used by Kalipei was too large, so he subtracted/kl from the four times of Kalipei's week. In western countries, the abbreviation A.D. is taken from Latin Anno Domini, in which Anno means "year", Domini means "Lord", English means "year in our Lord" and "year in the era of Christ", which roughly means "era of our Lord" and "era of Jesus Christ". BC is abbreviated as B.C., which means "year in our Lord".

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At present, the calendars used all over the world are called solar calendars, which are essentially solar calendars.

The original solar calendar was founded by the ancient Egyptians. At first, a year was considered as 365 days. In order to coordinate the length of the calendar year and the tropic year, the Roman ruler Julius Caesar revised the solar calendar in 46 BC and formulated the julian calendar. In the 8th year BC, Augustus, Caesar's nephew, adjusted julian calendar. Julian calendar is divided into twelve months a year, with an average of 365 days a year; A year divisible by 4 is a leap year, ***366 days. In this way, the average length of julian calendar over the years is 365.25 days, which is 0.7078 days different from that of the Tropic of Cancer (365.2422 days) and about 3 days different in 400 years. From the implementation in julian calendar to the end of16th century, the cumulative difference was about10th day. In order to eliminate this difference, Pope Gregory XIII set the second day of julian calendar 1582/kloc-0 10 on the 4th of October as15, and eliminated10 in the middle. At the same time, julian calendar's leap year rule is modified: the year divisible by 4 is still a leap year, but for century years (such as 1600, 1700, ...), only the year divisible by 400 is a leap year. In this way, there are only 97 leap years in 400 years, three less than the original, making the average length of the calendar year 365.2425 days, which is closer to the length of the tropical year. After this modification, julian calendar was called the Gregorian calendar, also known as the Gregorian calendar. The Gregorian calendar was first used in Catholic countries, and was widely used all over the world at the beginning of the twentieth century, so it is also called Gregorian calendar. China adopted the Gregorian calendar in 19 12, but still used the year of the Republic of China. 1949 After the establishment of People's Republic of China (PRC), the Gregorian calendar was adopted.

In the lunar calendar, the moon revolves around the earth for one month, but this period is only 29 and a half days, which is much worse than a year, so the leap month method is used to correct it. If there is only one solar term in the first lunar month, a leap month will be added to synchronize with the solar calendar.