The Gregorian calendar (1582- ) is the main calendar in the West. It is how days, months and years have been counted in English since 1752. It is the old Julian calendar of Julius Caesar as reformed by Pope Gregory XIII in 1582.
Today in different calendars:
- Gregorian: September 30th AD 2006
- Roman: September 17th 2758 AUC
- Alexandrian: September 17th AM 7498
- Byzantine: September 17th AM 7514
- Athenian: Puanepsion 7th Olympiad 696/2
- Hebrew: Tishri 8th 5767
- Muslim: Ramadan 7th 1427 AH
- Persian: Mehr 8th 1385
- Mayan: 126.96.36.199.6 (19 Chen 5 Cimi)
On the Gregorian calendar today is the 30th day of the ninth month (September) of the 2,006th year after the birth of Christ.
The day on the Gregorian calendar starts at midnight, following the Roman practice.
Week: Every seven days make a “week”. The days of the week are called:
Today is Saturday.
The Jewish Sabbath runs from Friday at sunset to Saturday at sunset.
Months: there are 12 months in a year:
- January (31 days)
- February (28 or 29 days)
- March (31 days)
- April (30 days)
- May (31 days)
- June (30 days)
- July (31 days)
- August (31 days)
- September (30 days)
- October (31 days)
- November (30 days)
- December (31 days)
January 1st, the first day of the year, falls on the 12th day of winter (in Europe) in most years, as it did in 2006.
Leap years: a year has a leap day (February 29th):
- If it ends in two zeros, like 1700 or 1600, and can be divided by 400 with no remainder. Example: 1600 and 2000 are leap years, but 1700 and 1900 are not.
- Otherwise, if it can be divided by 4 with no remainder. Example: 2004 and 2008 are leap years, but 2005 and 2006 are not.
The Julian calendar only had the second rule. By the 1500s it was 11 days off. With some advice from Copernicus, Gregory added the first rule and said that October 4th 1582 would be followed by October 15th – the very night St Teresa of Avila died.
The Gregorian calendar took hundreds of years to spread:
- 1582 Papal States, Venice, France, Belgium, Spain, Portugal, Latin America, Poland, Lithuania, Holy Roman Empire (Catholic states), part of the Netherlands
- 1584 Bohemia
- 1587 Hungary
- 1590 Transylvania
- 1612 Prussia
- 1648 Alsace
- 1682 Lorraine
- 1700 Denmark, Holy Roman Empire (Protestant states), north-eastern Netherlands
- 1750 Tuscany
- 1752 British Empire, Sweden
- 1867 Alaska, Finland?
- 1873 Japan
- 1916 Bulgaria
- 1917 Ottoman Empire/Turkey
- 1918 Russia
- 1919 Romania
- 1922 Soviet Union
- 1924 Greece (except Mount Athos)
- 1949 communist China
Switzerland came over messily in bits and pieces, most of it by 1701.
Both Shakespeare and Cervantes died on April 23rd 1616, but Cervantes died in Spain under the Gregorian calendar while Shakespeare died in Britain 11 days later under the Julian.
In the English-speaking world September 2nd 1752 was followed by September 14th.
Years are counted from the birth of Christ. Years after Christ are sometimes marked with AD (anno Domini) or CE (Common Era); years before Christ with BC (Before Christ) or BCE (Before the Common Era). For example:
- Aristotle was born in 384 BC, or 384 BCE or, simply, -384.
- Shakespeare was born in AD 1564 or 1564 CE or, simply, 1564.
There is no year zero.
– Abagond, 2006, 2016.
- calendar conversions:
- Christian Era (AD/BC)