The Gregorian calendar currently used in the world is a solar calendar, with 365 days in ordinary years and 366 days in leap years. There is a leap every four years, and there is one less leap every 100 years. There will be another leap every 400 years, that is, every 400 years. There are 97 leap years in the year. The average length of the Gregorian calendar year differs from the tropical year by only 26 seconds, and it would take 3,300 years to accumulate just one day.
The origin, change and development of the current Gregorian calendar
The Gregorian calendar currently in use around the world is the solar calendar that we are most familiar with. This calendar is steeped in the civilization created by mankind over thousands of years. It was learned by the ancient Romans from the Egyptians and spread throughout the world with the expansion of the Roman Empire and the rise of Christianity.
The earliest source of the Gregorian calendar can be traced back to the solar calendar of ancient Egypt. The Nile River is the lifeblood of Egypt. It was the need to calculate the flooding cycles of the Nile River that gave rise to ancient Egyptian astronomy and the solar calendar. Seven thousand years ago, they observed that after the day when Sirius first rose at the same time as the sun, the Nile River would begin to overflow five to sixty days later, so they used this day as the beginning of the year and calculated , this day is July 19th. Initially, a year was designated as 360 days, but later it was changed to 365 days. This is the world's first solar calendar. Later, they divided the year into three seasons based on the flooding of the Nile River and agricultural production, called flood season, winter and summer. Each quarter is 4 months long, each month is 30 days long, with 10 days in one week and 5 days in one week. There are 12 months in the whole year, plus 5 days at the end of the year, which are the year-end sacrificial days.
This calendar year with 365 days as one year was determined by observing Sirius and is called the Sirius year. It differs from the return year by about 0.25 days, so the start time of each year on the calendar is getting earlier and earlier. After 1461 calendar years, each date coincides with the original season again, and then gradually deviates from it. It seems that the Sirius year seems to be wandering around the tropical year cycle, so it is also called the wandering year or the wandering year. The 1461-year cycle is called the Sirius cycle.
Later, through astronomical observations, the Egyptians discovered that the true cycle of the year is 365.25 days. However, in order to maintain the "sacred" status of the religion in order to allow Egyptian festivals to be held at the same time as the worship of gods, the monks preferred to maintain Years of wandering. Later, a stone tablet was unearthed, with inscriptions in Egyptian and Greek, recording an order issued by Emperor Ogied in 238 BC: Every four years, after the five-day sacrificial day at the end of the fourth year , before New Year's Day next year, add another day, and hold the festival celebration of Emperor Ogied on this day so that everyone can remember it. Emperor Ogid corrected the defects of the previous calendar. The year with an additional day is called a fixed year, and the other years are called irregular years.
The calendar used by the ancient Romans went through the development process from the lunar calendar to the lunisolar calendar and the solar calendar. Rome was a small village in Italy in ancient times. The Romans first unified Italy and then became a large empire spanning Europe, Asia and Africa. At the earliest, the ancient Roman calendar had 10 months in the year, some with 30 days, some with 29 days (which is very similar to the lunar calendar), and 70 days of rest days at the end of the year. During the period of Romulus, the first king of Rome, the months had names and were arranged in order. There are 10 months in the whole year, some months have 30 days, some months have 31 days, and the other 60 days are year-end rest days. Taking the year when the city of Rome was founded, 753 BC, as the first year, this is the Roman Era. Some European historians continued to use this chronology to record historical events until the end of the 17th century.
The second king, Numa, reformed the Greek calendar, adding the eleventh and twelfth months, and also adjusted the number of days in each month to 1, 3, 5, and 8. There are 31 days in each month, 29 days in 2, 4, 6, 7, 9, 10 and 11. December is the shortest month with only 28 days. According to Roman custom at that time, even numbers were unlucky, so all the condemned prisoners for the year were executed in this month. In this way, the calendar year has 355 days, which is more than 10 days less than the tropical year. In order to correct the deviation of dates and seasons year by year, two supplementary months are added every four years. The first supplementary month has 22 days and is added in the second year. The other 23 days is added in the fourth year. The increase is The number of days is placed between the 24th and 25th of December. This is actually a lunisolar calendar. The average length of a calendar year is 366.25 days. At the same time, the method of adding or subtracting supplementary months is used to remedy the shortcomings of the calendar and the weather. But this only adds to the confusion: the months move around haphazardly. For example, the chief priest in charge of the calendar would forcefully insert a month into the year when his friend was in power, and when his enemy was in power, he would add less months to shorten his term. The execution of folk contracts was also affected. Sacrifice festivals and fasting days were gradually moved, and the harvest festival that was supposed to be in summer was actually held in winter.
When Julius Caesar became consul for the third time, he appointed a group of astronomers headed by the Egyptian astronomer Sosichenius to develop a new calendar, which was the Julian calendar.
The main content of the Julian calendar is: a leap year is set up every three years, with 365 days in an ordinary year and 366 days in a leap year. The average length of a calendar year is 365.25 days. The original November 1st was used as the beginning of the year, so that it would coincide with New Year's Day when the Roman consuls took office. The Julian calendar is divided into 12 months each year. The 1st, 3rd, 5th, 7th, 9th, and 11th months are the big months, and the big month has 31 days each month.
The 4th, 6th, 8th, 10th and 12th months are small months with 30 days in each month. The second month (the original twelfth month) has 29 days in ordinary years and 30 days in leap years. Although the month sequence is different from before the calendar change, it still retains its original characteristics and is the shortest month of the year.
The Julian calendar was implemented in 709 AD, that is, January 1, 45 BC. In this year, in order to make up for the annual difference between the Roman calendar and the solar year, in addition to the 355-day calendar year and an additional 23-day month, two more months were inserted, one of which had 33 days and the other had 34 days. In this way, there are 355+23+33+34=445 days in this year. This is what history calls "the years of chaos."
The Western calendar has finally gotten on the right track since the implementation of the Julian calendar. What’s funny is that the priests who issued the almanacs had the ability to predict good and bad fortunes from the battles of crows, but they misunderstood the order to change the calendar to “set up a leap year every three years” as “set up a leap year every three years.” This error was not corrected until Augustus ordered it in 9 BC.
Augustus means sacred, solemn and sublime. In ancient Rome, this title was only awarded during religious ceremonies. In 27 BC, the Senate awarded it to Octavian. He was the son of Julius Caesar's sister and the first heir to Caesar's will.
I think back then, the great Emperor Julius Caesar fought in the north and south, conquered the east and west, was a man of great talent and arrogance, and later became a de facto dictator. The tree is big and attracts the wind, and is envied by many people. In 44 BC, when Caesar intended to proclaim himself emperor publicly, he was assassinated in the Senate chamber. At this time, Octavian was not yet 20 years old, but he was quite intelligent and skillful, and gradually accumulated strength. By 30 BC, he defeated all opponents and became the "first citizen" of Rome. Octavian was actually the only ruler with unlimited power, and he ended the Roman War. Therefore, Rome, which began in 27 BC, was historically called the Roman Empire.
When Augustus was about to correct the leap year error, there had already been three extra leap years, so he ordered that leap years be stopped from 8 BC to 4 AD, that is, 5 BC, 1 BC and AD 4 was still an ordinary year, and later it returned to a leap year every four years. In order to commemorate his achievement, the Roman Senate passed a resolution to rename the eighth month of the Julian calendar as "Augustus", the month of Augustus, because he had achieved great military victories in this month. But this month is a small month, which is a bit inferior. Besides, the Romans regarded odd numbers as auspicious, but 30 days is an even number, so they took one day from February and added it to the month of Augustus, making August 31 days. Well, poor February only has 28 days in normal years, and only 29 days in leap years that occur every four years. July, August, and September were all big months for three consecutive months, which looked very unpleasant and inconvenient to use, so we changed September to 30 days, October to 31 days, November to 30 days, and December to 30 days. 31 days. In this way, the pattern of large and small moon phases was destroyed, and it is still affected today, two thousand years later.
The format of the calendar revised by Augustus is exactly the same as the current Gregorian calendar, but its era, that is, the starting point for calculating the era is not the first year of the Christian era, and its leap year method is not completely consistent with the current Gregorian calendar. . These two differences are closely related to the origin and development of Christianity.
Christianity originated in Palestine in the first century AD. The word "Christ" is a transliteration of ancient Greek, meaning "Savior." Legend has it that the founder of Christianity is Jesus. As the savior, he promised that the poor would ascend to heaven after death, while it was harder for the rich to enter heaven than for a camel to pass through the eye of a needle. Because it touched the heartstrings of the lower class people, Christianity gradually spread and caused uneasiness among the Roman rulers. During the era of Emperor Tiberius, the Roman governor in Judea had Jesus crucified. But on the third day, Jesus resurrected from the tomb and ascended to heaven. He will also execute the last judgment on all the dead and living in the future. Later, Christians recorded these legends and Jesus' words and deeds and compiled the New Testament.
Early Christianity was suppressed many times because it broke the theocratic rule of the Roman Empire. Later, as the Roman Empire declined and slavery disintegrated, the original upper-class members of society joined Christianity one after another in hesitation, and gradually took control of it, trying to seek support from the rulers for the church. The rulers turned to adopt a soft policy toward the church, and by the end of the fourth century, the Roman Empire finally declared Christianity as its state religion.
The era of the Gregorian calendar is calculated from the year "Jesus was born". This is closely related to the rise of Christianity.
After that, the Julian calendar was considered to be an accurate calendar, so people fixed March 21 as the vernal equinox, but it brought unexpected troubles. As time went by, people discovered that the true vernal equinox was no longer consistent with the calendar at that time. The date when day and night were equal became earlier and earlier, and by the end of the 16th century it had been advanced to March 11. The reason why the spring equinox is gradually advancing is because the Julian calendar is not the most accurate calendar. Its average length of the calendar year is equal to 365.25 days, which is still 11 minutes and 14 seconds longer than the return of the tropics. Although this difference is not large, it adds up to a difference of 128 years. One day is just over three days short of 400 years.
In order not to violate the provisions of the synod and to meet the church's requirements for the calendar, Pope Gregory XIII set up a special committee to reform the calendar. After comparing various plans, he decided to adopt the method used by Italian doctors. Leo's plan would eliminate the three extra leap years in the Julian calendar in 400 years.
On March 1, 1582, Gregory issued an order to change the calendar, which read:
1. The day after October 4, 1582 is October 15, and It is not October 5th, but the week numbers are still calculated continuously. October 4th is Thursday, and the next day, October 15th, is Friday. In this way, the old debt accumulated since 325 AD was written off.
2. In order to avoid the phenomenon of spring equinox drifting away in the future, the method of changing the leap year is as follows: Any AD year that can be divisible by 4 is a leap year, but when the AD year is followed by "0" with two "0" Century year", the year must be divisible by 400 to be a leap year.
The average length of the Gregorian calendar year is 365 days, 5 hours, 49 minutes and 12 seconds, which is 26 seconds longer than the return period. Although based on this calculation, there will still be an error of one day in about 3,000 years, but this accuracy is already quite remarkable.
Because the content of the Gregorian calendar is relatively concise, easy to remember, has high accuracy, and is consistent with the weather, it is gradually adopted by governments around the world. Our country officially used the Gregorian calendar on January 1, 1912, according to the provisional government after the Revolution of 1911.
This is a bit of knowledge about astronomy. I hope more people like astronomy.
Meixiang Xuehai Brief description on the Internet at the end of September