A Matter of Time

Calendars through the ages - Ancient calendars

Thirty days has September,
April, June, and November.
All the rest have thirty-one
Except for February
Which has twenty-eight
And on a leap year
Has twenty-nine.
Ancient mnemonic rhyme

The Beginning of the Calendar

In Rome, around the time of the eighth century, priests routinely called out the arrival of the new cycle of the moon, thereby announcing the beginning of a new month. The Romans referred to this as Kalends, from their word calare, which means to announce solemnly. From this tradition, the word calendar was born. Long before that, the Egyptians, soon followed by the Babylonians, formulated 365-day years and began the process of measuring time. These people initiated what are now collectively referred to as the ancient calendars.

Celestial Bodies

The sun was the first item used to help people create a calendar. It was useful for figuring out how many days had passed by, but it didn’t really provide clues as to which day it actually was. The Babylonians were the first to set up a system to differentiate between days based on a lunar month, or the time that passes between the appearance of two full moons. A more accurate measure of a lunar month would be twenty-nine days, twelve hours, forty-four minutes, and 2.9 seconds. A 12-month year based upon an accurately measured lunar month, however, only adds up to 354.3 days. That means that even by the third or fourth year into this system, the day marked off for the beginning of the harvest would no longer be in the right position, or over time, even in the right season because, a year is not really 354 days long. Due to this discrepancy, a day thought to be June 1st , according to the calendar, would eventually be May 1st , according to the season. To fix this, the Babylonians simply added days onto their calendar through a process known as intercalation. This process still goes on today when dealing with leap years.

The ancient Egyptians utilized the stars instead of the moon to keep track of time. They noticed that the stars didn’t move across the sky randomly, but rather moved in a pattern. They also determined that the brightest star, now known as Sirius, could be conveniently used to keep track of this movement. Every three hundred and sixty five days, Sirius was right at the horizon in the morning. Soon after that, the Nile always flooded, and so this was used to mark the beginning of the year. The problem of Sirius showing up one day late every fourth year was acknowledged by the Egyptians only in that they knew this happened and accurately predicted the timing of the floods accordingly, but they never changed the calendar to reflect the extra one-fourth of a day they knew each year had.

Ancient Rome

The internationally accepted calendar of today has its origin in Rome. Originally it had ten months, known as Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November, and December. If you look at the root words of these months starting with Quintilis, it can be seen that they have been named for the numerical order that they are in - five, six, seven, eight, nine, and ten. Of course today November isn’t the ninth month, and December isn’t the tenth. The Roman year however only added up to 304 days, so King Numa of Rome tried to fix the problem in 712 BC by inserting Januarius and Februarius at the beginning, right before Martius. Even after he modified the days that were allotted to each month, the calendar still wouldn’t work, as it then had 366 days.

Julius Caesar was faced with a calendar disaster when he was in power. The calendar was seriously out of pace with the seasons and people were frustrated because traditional holidays were no longer being celebrated at the same time of year they were when Rome was first founded. In order to return the traditional holidays to their proper place within the solar year, he added 67 days to the year 45 BC and introduced a modern calendar with twelve months of 30 and 31 days. This established a system with 12 months and 365 days, with one extra day every four years, just like we have today. Thus the Julian Calendar, named after Julius, was born. That’s also not the only thing that was named after him; he changed the name of the fifth month from Quintilis to Julius as a reward for all of his efforts. When the next emperor came to power he took it upon himself to make one final adjustment. The sixth month, formerly known as Sixtilis, became Augustus in honor of him, Caesar Augustus. He also stole a day from February so that his month would have 31 days like Julius’ did, making February even shorter than it already was with a final tally of only 28 days.

It seemed as though the calendar problem had finally been fixed because these reforms lasted for over 1500 years. As it turns out, however, a year isn’t exactly 365 1/4 days long. That would be 365 days and 6 hours. In reality, a year is only 365 days, 5 hours, 48 minutes and 46 seconds long. This 11 minutes per year discrepancy added up over the centuries and finally threw things out of whack once again. By the sixteenth century, the Vernal Equinox had slipped from March 21 to March 10 so Pope Gregory XIII made yet another shift in the calendar in 1582. To drop the excessive 10 days that had accumulated over the years, he decreed that the day after October 4, 1582 would be October 15, 1582. He also changed the way leap years were to be calculated so that years ending in 00 were no longer leap years. And lastly, he changed the beginning of the calendar year from March 25 to January 1. Though it took over 100 years to have his calendar accepted by all nations, it is now globally accepted for purposes of trade and daily business.

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