The Julian calendar (fl. -45 to 1582) was the Roman calendar as reformed by Julius Caesar. It was the main calendar used in the West till Pope Gregory XIII reformed it in 1582, giving us the Gregorian calendar, still the main Western calendar in 2018.
The English-speaking world used the Julian calendar till 1752, which is why George Washington has two birthdays – he was born under the Julian calendar on February 11th 1732, which was February 22nd on the Gregorian calendar.
Some Eastern Orthodox churches still use the Julian calendar, which is why Christmas and sometimes Easter falls on a different day than it does in Catholic and Protestant churches. December 25th on the Julian calendar is currently January 7th on the Gregorian.
It all began with Caesar and Cleopatra:
In the year -48 (48 BC), Julius Caesar fell in love with Cleopatra. At one of her parties he met Sosigenes, an astronomer. Egypt had the best calendar of the Mediterranean world. Sosigenes said it was different from the Roman calendar in three main ways:
- It kept in step with the seasons, not the phases of the moon. (The Roman calendar tried to do both and failed.)
- Its months added up to 365 days.
- Every fourth year had a leap day added.
Julius Caesar reformed the Roman calendar accordingly.
The year -46 was the Year of Confusion. It was 445 days long with a leap month after February and two after November. Caesar did that to get the first day of spring back on the traditional date of March 25th.
On January 1st -45, the Julian calendar began. It had these months:
- January (31 days)
- February (28)
- March (31)
- April (30)
- May (31)
- June (30)
- Quintilis (31)
- Sextilis (31)
- September (30)
- October (31)
- November (30)
- December (31)
Mercedonius, aka Intercalans, was dropped. It was the old Roman leap month added after February 23rd. The leap day, February 29th, took its place.
In -44, when Julius Caesar died on the Ides of March, the Senate named Quintilis after him, which is still called July in English.
In -8, Augustus named Sextilis after himself, the month in which he defeated Antony and Cleopatra. Some scholars say he robbed February of a day to make August as long as July.
From -8 to +8 there were no leap days. Because the priests had added too many, adding them every three years – “in the fourth year” according to inclusive counting.
In 321 Constantine added the seven-day week:
- Sun day (Sunday)
- Moon day (Monday)
- Mars day (Tuesday)
- Mercury day (Wednesday)
- Jupiter day (Thursday)
- Venus day (Friday)
- Saturn day (Saturday)
That year began on Sunday January 1st.
The week is a Babylonian invention from the -600s, which came to Rome by way of the Christians and Jews.
In the early 800s Charlemagne ruled most of the West and made common the practice of numbering years from the birth of Christ: AD and BC. But not everyone agreed when the year started. Some said it started in January, others in March.
In the 1500s the calendar was off by ten days. With the help of Copernicus, the pope in Rome reformed the calendar giving us the Gregorian calendar.
– Abagond, 2018.
Sources: mainly Google Images (2018); “Calendar” (1998) by David Ewing Duncan; “Calendar” (1989) in the Encyclopædia Britannica.
See also:
- calendars
- AD (Anno Domini)
- Eastern Orthodox Christmas
- people and places:
- Alexandria
- Eratosthenes
- Cleopatra
- Sosigenes
- Rome
- Julius Caesar
- Gregory XIII
- Copernicus
- Alexandria
554
Dude, it’s the Julian calendar and you’ve got an image of everyone except the namesake Julius Caesar!
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@ Solitaire
LOL!
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@ Solitaire
Put a picture of Julius Caesar at the top.
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@ Abagond
Much better, thanks! 😉😂
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Nitpicking: the astronomical notation -x for BC years incorporates year 0, so -1 is 2 BC, etc
https://eclipse.gsfc.nasa.gov/SEhelp/dates.html
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I prefer to use BCE/CE. It makes more sense to me.
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The astronomical convention has advanges. How many years between 15 BC and 15 AD? Was 15 BC a leap year? Using -14 the answer is obvious
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I am wondering when the rest of the world decided to accept the Julian calendar as the global standard.
Also, I was wondering when we will see more posts on the other calendars in common use in the world, eg, the Chinese calendar (both the solar and lunar versions).
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@ Alberto Monteiro
At a practical level, nearly everyone is going to forget about there being no 0 BC and just assume that -322 or whatever means 322 BC. Which is fine. I am not the only one who writes BC/BCE that way. So does Joseph Needham, L. Sprague de Camp, and the UNESCO history of Africa.
I absolutely loathe BC. And calling it BCE does not make it much better. I hate dates that run backwards. I say that as someone who has read quite a bit of Greek and Egyptian history. What I like about using a minus is that at least it makes it clear that the dates are in fact running backwards.
AD and BC are way better than what went before (naming years after rulers), but starting AD or AH or any year-numbering scheme in the middle of recorded history is, frankly, nuts. But it is what we have.
Personally I would prefer something like the Holocenic era, which adds 10,000 to the Western year:
https://en.wikipedia.org/wiki/Holocene_calendar
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Hi brother Abagond,
Do you mind checking out my Instagram page. I created a model that I believe will help our people unlock their hidden brain potential. I want to create a blog based off my ideas. Where do I start?
https://www.instagram.com/the_holy_compass/
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Before the Christian Calendar there was a much better system, used for astronomical calculations: the age of Nabonassar, with its origin around 700 BC and years of 365 days
http://www.sacred-texts.com/astro/argr/argr06.htm
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@ Alberto Monteiro
“Before the Christian Calendar there was a much better system”
Do you mean better than the Julian calendar? Because I’m not seeing that. It was a lunar calendar with intercalary months and irregular weeks.
https://en.m.wikipedia.org/wiki/Babylonian_calendar
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No, sorry, the system I mentioned is better for registering astronomical observations, since it básically counts the days since its epoch.
The Page below is in Portuguese, but I wrote it using sources in English. Just click the links
https://pt.m.wikipedia.org/wiki/Calendário_de_Nabonassar
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@ Alberto Monteiro
Thank you for the clarification.
Although I will say your cited sources are very old, and I would be more interested in seeing a modern-day assessment.
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That’s because while writing for Wikipedia it’s a good practice to use free and non-copyrighted sources. Also, these sources might be too eurocentric: some of them even suggest that egyptian astronomy derived from the greeks. Now we know it was the other way
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