There are more, but in my travels, I have discovered three different calendars that people use in the world today. Most of the people who live in the west use the Gregorian Calendar. The Orthodox Church uses the Julian Calendar, and some of the people in the east use the Lunar Calendar while others use the Gregorian Calendar in the east. This causes holidays to be celebrated at different times in different countries. Today, January 7th, is the Orthodox Christmas, but most of us had Christmas back on December 25th. We have just celebrated the New Year, but the older people in Korea and the Chinese won’t celebrate New Year this year until January 25th. If you go to Romania, there are two Easters every year. They may only be a week and sometimes two weeks apart. They call one the Catholic Easter, and the other, the Orthodox Easter. The Catholics use the Gregorian Calendar, and the Orthodox use the Julian Calendar in Romania. The Japanese use the Gregorian Calendar, and the younger Koreans use the Gregorian Calendar, but they also like the benefit that the whole country also uses the Lunar Calendar, and so they get several weeks off of school or work for the Lunar New Year, what the rest of the world calls “the Chinese New Year.” What is going on here?
In the west, the Julian Calendar was made by Julius Caesar in 46 B. C. It was to replace the old Roman calendar. The Julian Calendar is a solar calendar. It has 365 days per year, but every fourth year, it has 366 days, and that year is called the leap year. The names of the months are on this calendar are: December, Ianuarius, Februarius, Aprilis, Maias, Iunius, Quintilis, Sextilis, September, October, November. I got these from Wikipedia, but I have actually seen a Julian calendar that had only ten months and the names of the months were slightly different.
The Gregorian Calendar, a new and improved solar calendar, has replaced the Julian calendar in most places except in the Orthodox church. Pope Gregory XIII created the Gregorian calendar in 1582 B. C.. Everyone didn’t adopt it right away, but slowly, many countries have adopted it. English adopted it in the 17 hundreds which means it was brought to America when they came. Japan adopted it in 1873. Korea adopted the Gregorian calendar in 1872, but not for all purposes. They also still use the lunar calendar in Korea. The Chinese adopted it in 1912, but also continued using the lunar calendar for certain things. Slowly, country by country, they have adopted the Gregorian Calendar. Most countries in the world today use the Gregorian calendar, and many use another calendar too that was already in use in their county when they adopted the Gregorian calendar. Non Catholic countries, Arab countries, and others that were not European took longer to adopt it than most European countries. It has become a standard calendar for most of the world.
The lunar calendar dates back to the 14th century B. C., and the legend says that a Chinese emperor invented it. When we lived in S. Korea, we had a church calendar hanging on our wall that my daughter’s father in law gave us every year. For every month and day, the Gregorian month and day were marked, and so was the month and day of the Lunar Calendar. I have a cell phone I still use from S. Korea, and on my cell phone, it gives me the Gregorian date and the Lunar date. Today, January 7th, is December 13th on the Lunar Calendar. Some countries keep the old ways and go on and embrace the new at the same time.
The continuity of everyone using the same calendar helps things runs smoothly internationally. However, I can see some benefit to the countries who also keep the old calendars. We have lost the real birth date of Jesus, but most agree he was probably born in the spring rather than in the winter. . Different people celebrate Easter at different times, but there is agreement that Jesus was, at least, crucified in the spring even if they can’t agree on which day. If we keep the old calendars, we have some reference point for history. However, this is why holidays are celebrated at different times in different countries. Everyone had a calendar before the Gregorian calendar was invented, and some countries or religions still use the old calendars.