Gregorian calendar

The **Gregorian calendar** is the calendar that is used throughout most of the world. It began being used in 1582. It replaced the previous Julian calendar because the Julian calendar had an error: it added a leap year (with an extra day every four years) with no exceptions. The length of the Julian year was exactly 365.25 days (365 days and 6 hours), but the actual time it takes for the Earth to go around the Sun once is closer to 365.2425 days (about 365 days, 5 hours and 49 minutes). This difference is about eleven minutes each year. In Europe's Protestant countries, people feared that the new calendar was an attempt by the Catholic Church to silence their movement.  Since the Great Schism, Europe's Eastern Orthodox churches also ignored the Pope's decision and many continue to use the Julian calendar even today.

### British Empire
England and the rest of the British Empire (including what is now the US and Canada) adopted the Gregorian calendar in 1752. Because 1600 was a leap year in both calendars but the Julian calendar had a leap year in 1700 but the Gregorian calendar did not, this meant that *eleven* days needed to be skipped. Wednesday, September 2, 1752 was followed by Thursday, September 14, 1752.

### Russia 
In the USSR, the October Revolution of 1917 was celebrated in November. In 1917 the Russian Empire still used the old Julian calendar. Changing the calendar meant 365 days after the revolution started was now in November 1918.

### Churches 
In 1923 some Eastern Orthodox Churches changed to the Gregorian calendar. Christmas Day is the same as the Catholic and Protestant churches, but the date of Easter continues to be worked out differently.

The Russian Orthodox Church, as well as some other Eastern Orthodox Churches such as Georgian and Serbian, did not want this change, so Russian Christmas Day is about two weeks after the rest of Europe.

### Japan 
Japan adopted the Gregorian calendar's way of working out leap years on January 1, 1873, but the months have numbers instead of names. Japan also starts year one with each new reign, but uses reign names not the name an emperor might be best known by in the west. For example, the reign names *Meiji* year 1=1868, *Taisho* 1=1912, *Showa* (Emperor Hirohito) 1=1926, *Heisei* (Emperor Akihito) 1=1989, and so on. The "Western calendar" (西暦, *seireki*) using western year numbers, is also widely accepted by civilians and to a lesser extent by government agencies.

## *Old Calendar* in Britain 
### Old Style and New Style dates 
Some old dates in Britain were written and documented with two different years. This is because Britain did not start a new year until March 25, so for a few months it was one year in Britain and the next year in other countries.

The letters OS (for *Old Style*) and NS (for *New Style*) were used to help determine the year being used. For example, King Charles I died on January 30, 1649. In "Old Style" it is correct to say that Charles I died *January 30, 1648 (OS)*. Using "New Style", as we determine dates now, the correct date and year would be February 9, 1649.

### British Tax 
In the old calendar, the year started on March 25, this was the Quarter Day when rents and taxes fell due. This became April 5 which is why the tax year in the United Kingdom begins on April 6. 

## Timeline 

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  from:1896  till:1896  text:"1896~Korea"
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  from:1916  till:1916  text:"1916~Bulgaria"
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  from:1919  till:1919  text:"1919~Romania, Yugoslavia
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People sometimes use the term N.S. or New Style to mean the Gregorian calendar, with Old Style (or O.S.) meaning the Julian calendar.

## Related pages 
* Julian calendar
* Solar calendar

## Notes 
## References