Monday, November 14, 2016

A Brief History of the Western Calendar

Time is an abstract notion. It takes a trained and smart mined to measure it and arrange it into a readable calendar. For over one thousand years, we have been working on the calendar as we know it today.


Albert Einstein once said "The only reason for time is so that everything doesn't happen at once". For the genius physicist this possibility could actually became feasible but for ancient people things happened at different moments. They noticed the sun going down, the star rising, the sun going up again, the birth of a child, the death of an elderly, the plants growing and cropping, the trees changing from green to yellow and so on.
People did not invent the time, they just ordered it, gave it a name and tried to arrange their lives around it. So, they made calendars, time machines and kept records of their most important events, so that now, we would remember them. And we do, as much as we can.

The Babylonians and their calendar

The first ones to divide a year into 12 months were the Babylonians. They observed the rising of the stars, that happens before down. Day after day, during a year, they noticed that the sun passes the same stars at the same time. They divided the sky into 12 constellations and a period in which the sun passed a constellation became a month. The month then was divided into thirty days.
Elizabeth Taylor as Cleopatra

This nice arrangement would have worked well if not for the moon. The moon was a very important deity, well venerated in many societies. The moon did not have the same cycle like the sun. We know now that the solar cycle is a 30.4 days while the moon cycle is about 29.53 days. So, there is a shift of an average of a day for each successive month. The two celestial calendars needed to be corrected. There were many attempts to align the two cycles. Again, about 499 B.C. the Babylonians came up with a plan. On a period of 19 years, the third, fifth, eighth, eleventh, thirteenth, sixteenth and nineteenth year had an extra month.

Another idea we inherited from Babylonians was the division of a month in a seven-day period, each of the periods ending with an "evil day", to please the goods. The days were named after the seven planets that, opposed to the stars, appeared to change position.
The division of a day in 24 hours seems to come from Egypt, but later, the Babylonians, started to divide an hour in periods of 30s and 60s which came to us as seconds and minutes. The Babylonians were very good astronomers and their knowledge spread around the Orient and Occident, reaching China and Indian, Greece and Rome.

The Romans and their calendar

At the time Julius Caesar change the Roman calendar, in 45 B.C., the time in ancient Rome was somewhat out of control. The time before his reform were also called "the years of confusion".
Christopher Plummer as Julius Caesar
At first, Rome had a 10-month calendar that began in March. Numa, the second king of Rome, introduced 2 more months. In time the Romans produced a 24-year cycle with about 355 days/year and leap years of 277 or 278 days, coming to an average of 365.4 days per year in a cycle. Pretty good. But why would they change it? The reason was political. Numa also appointed the Pontiffs Maximus (the great priest) to take care of the calendar and correct it, adding the intercalary months when needed. The pontiffs were also involved in politics. A magistrate position in Rome lasted 1 year so the pontiffs could make it shorter or longer, according with their interests, by adding or omitting the intercalary months.
By the time Caesar became dictator in Rome (46 B.C.), the calendar was drifting so far away that the crossing of the Rubicon did not take place in January 10, 49 B.C. but earlier in mid-autumn. He started by lengthening the year of 46 B.C. introducing the month that had been missing during the " years of confusion". With the help of astronomer Sosigenes of Alexandria (little is known about him) Caesar regulated the calendar: a year had 365 days, divided into 12 months, with a leap day added every 4 years to the month of February. Every year begun in January, the month that magistrates took office in Rome. This is the calendar we are using today.

Later reforms of the calendar

Pope Gregory XIII

The main reform later introduced to the Julian Calendar was introduced by Pope Gregory XIII in 1582, that decreed that October the 5th 1582 should be October 15th. This 10 days drift was meant to align the calendar year with the tropical year (a period in which the Earth completes an orbit around Sun).

The reform also slightly corrects the leap years and the time we celebrate Easter.

    The name of the days
•             Sunday - sun's day (Latin Domenica - the day of the Lord)
•             Monday - moon's day (Italian - lunedi - they of the Moon)
•             Tuesday - the day of the Nordic warrior god Tyr (Italian - martedi - Mars' day)
•             Wednesday - the day of the god Odin (Italian - mercoledi - Mercury's day)
•             Thursday - the day of the god Thor (Italian - jovedy - Jupiter's day)
•             Friday - the day of the wife of Odin, goddess Frigg (Italian - venerdi - Venus' day)
•             Saturday - Saturn's day (Italian Sabato - from Jewish Shabbat, the seventh day)

Also from Romans we inherited the name of the months:
1.            January - from Ianus, the god of gates, beginnings and endings
2.            February - from the roman festival of Februa (purification) which took place on February 15th
3.            March - from Mars, the god of war
4.            April - from the Latin term "aperire" that means "to open"
5.            May - from Maia, the Greek goddess of fertility
6.            June - from goddess Juno, the wife of Jupiter
7.            July - from the month when Julius Caesar was born
8.            August - in the honor of emperor Augustus
9.            September - from "septem", that means "seven" because originally it was the seventh month of the year
10.          October - originally the eighth month of the year
11.          November - originally the ninth month of the year
12.          December - originally the tenth month of the year

Year 0 for
•             Christians - year 0 the birth of Jesus (year 4 BC)
•             Romans - 753 BC, foundation of Rome
•             Greeks - 776 BC, the first Olympiads
•             Egyptians - 2773 BC, the introduction of the calendar
•             Chinese - 2637 BC, not sure but this is the year for the first Chinese calendar
•             Jewish - 3761 BC, the date of Creation Muslims - 622 AD, Hegira

Note: I previously published this article in a website called Hubpages. As the website changed its format, I decided to take it down and put it on my own blog. In the future, there would be other articles coming here. Stay tuned.