In today's trivia we try and work out what that deal with February is:
- Why is this month shorter than the rest?
- Why is it used for the leap year offset?
Recreation of a Roman fasti, an official list of public days when official business could be conducted and celebrations would take place, based on the Roman calendar
Origins of the Months
Before we can answer those questions we need to dig a little into the history of calendars and where the Months of the Gregorian calendar come from.
Calendar of Romulus
To start, we need to go back as far as the formation of the Roman Empire. The first documented calendar we know they used was the Calendar of Romulus. A solar calendar in that it related to the progress of the Earth around the Sun, as opposed to a Lunar calendar which tracks progress of the Moon around the Earth.
This calendar is interesting for a number of reasons:
Martius (31 days)
Aprilis (30 days)
Maius (31 days)
Iunius (30 days)
Quintilis (31 days)
Sextilis (30 days)
September (30 days)
October (31 days)
November (30 days)
December (30 days)
This calendar consists of ten months and a total of 304 days. The remainder of the year, the winter months were not tracked by the calendar. Instead the calendar was started each year at the spring equinox occurring in the first month of the calendar.
This strikes me as particularly convenient as it resolves a common problem with early calendars. That of drift of the calendar against the seasons. Lunar calendars for example track the progress of the Moon each month. But a Lunar month is 29.5 days long (354 days) and so does not coincide with the solar year (365.2 days) so for a Lunar calendar to track the seasons, they need an offset month known as an intercalary month to be added each year to correct for the drift.
Finally we see that there are some months we recognise. The origins of all the months is not entirely clear but we can certainly see a few we recognise. The last six months indicate their positions in the calendar based on the Latin words quinque, sex, septem, octo, novem and decem.
Calendar of Numa
At some point during the reign of Numa Pompilius (715–673 BC) a refined version of this calendar was introduced. The Romans of the time considered even numbers to be unlucky, so they removed a day from each of the even numbered months (Aprilis, Iunis, Sextilis, September, November and December). Combined with the winter months there was enough days to define two extra months of January (29) and February (28). February being 28 days long was considered a suitable candidate for Februa the Roman festival of purification which we imagine is where its name comes from.
Ianuarius (29)
Februarius (28)
Martius (31)
Aprilis (29)
Maius (31)
Iunius (29)
Quintilis (31)
Sextilis (29)
September (29)
October (31)
November (29)
December (29)
This brings the total days to 355. This calendar would of course drift each year.
As mentioned above, the Romans added an intercalary month when it was thought necessary (every two years) to bring the calendar inline with the solar year. On a year when they added an intercalary month, February would end on the 23rd (Terminalia) and the month would month would be added. This extra month would be either 27 or 28 days (377 or 378 for the year).
The average of every two years would bring the calendar to 366 days a calendar year. This made for a more workable system.
That was until the Romans started using the intercalary month for political purposes. The position of Pontifex Maximus was responsible for setting the length of the intercalary month. The office of Pontifex Maximus was generally held by a member of a politically prominent family. It was a coveted position mainly for the great prestige it conferred on the holder. Since the term of office for a political official was determined by the calendar year, there are indications that the length of the year was open to debate.
For example, Julius Caesar made the year of his third consulship in 46 BC 445 days long.
Julian Calendar
In the same year, Julius Caesar, as Pontifex Maximus reformed the calendar in 46 BC. The new calendar became known as the Julian calendar. This calendar proved very successful as it was in use up until 1582 when the Pope Gregory mandated the use of the Gregorian calendar system.
Ianuarius (31)
Februarius (28)
Martius (31)
Aprilis (30)
Maius (31)
Iunius (30)
Quintilis (31)
Sextilis (30)
September (30)
October (31)
November (30)
December (30)
This gives a total of 365 days with a leap day added to February every four years which gives the Julian calendar an average of 365.25 days a year. This was only later improved upon by the Gregorian calendar in the West.
This system was primarily introduced because maintaining the intercalary month of the Numa calendar was proving both an administrative burden, and a political complexity which tended towards the average Roman some distance from the city not knowing the date. The last three years before the switch to the Julian calendar where remarked as "years of confusion".
After its introduction, it proved useful. Varro used it in 37 BC to fix calendar dates for the start of the four seasons, which would have been impossible only 8 years earlier. A century later, when Pliny dated the winter solstice to 25 December because the sun entered the 8th degree of Capricorn on that date, this stability had become an ordinary fact of life.
Gregorian Calendar
The final stop on this chronological tour is the Gregorian Calendar we are all familiar with which was established in 1582 by Pope Gregory XIII. It can be summarised as follows:
"Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is."
The calendar was a refinement to the Julian calendar amounting to a 0.002% correction in the length of the year. The motivation for the reform was to bring the date for the celebration of Easter to the time of the year in which it was celebrated when it was introduced by the early Church. Because the celebration of Easter was tied to the spring equinox, the Roman Catholic Church considered the steady drift in the date of Easter caused by the year being slightly too long to be undesirable. The reform was adopted initially by the Catholic countries of Europe. The last European country to adopt the reform was Greece, in 1923.
Conclusion
So to conclude, we can tell that calendars became hugely important in civilisations. The moment there was demand for agriculture, civic planning, trade and commerce etc there will be a demand for coordinating activities via a calendar. Every major civilisation has developed its own calendar system to help track the days and months of the solar year.
To answer the specific questions of February, we can now say it is the short month because of a combination of factors:
- Early calendars were lunar and so each month was roughly the same length
- Most calendars could not precisely follow the solar year
- The Roman calendars used the month of February to adjust the length of the year
- The Julian calendar also uses February for the leap year adjustment
- Which is why we still use February to track leap years in the Gregorian calendar.
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