Wednesday, January 4, 2012

Calendar Evolution

The term “calendar” originated from the Latin word kalendae, which pertains to the “first day of every month.”

It is not known when the first calendar was made and who made it. But we know for a fact that, in the Bible, there were already chronological records even before Noah's time in the Book of Genesis, which is approximately 4,300 to 6,800 years ago. This approximation corresponds to the oldest archaeologically verified civilization, the Sumerians, and to their system of recording time.

Even much earlier, Stone Age people marked the passing of days by etching the walls of caves. Ancient Filipinos reckoned time by tying knots in a string to remember the days, or counting the full moons and carving the counts on bamboo poles. This is important for them in knowing when the palay should be harvested after planting, or monitoring the onset of the rainy seasons, as well as keeping track of their ages.

Later on, the periodic occurrence of natural phenomena helped the ancient people to measure time. The day equals the time the earth rotates on its axis, the complete passing of morning and night. The lunar month marks the time it takes the moon to complete its revolution around the earth. The solar year is the equivalent to a full circle of the earth around the sun.

In Mesopotamia (ancient Iraq), the first calendars of the Sumerian city-states were lunar (based on the movement of the moon). The Sumerian month begin with the moon's first crescent, and the lengths of the months varied with the period of the moon – 29 or 30 days – which is the same breakdown found among certain Stone Age recordings.

The Egyptians were the first people to adopt a predominantly solar calendar. They were also among the first astronomers of ancient times, and their knowledge of astronomy helped them device their calendar. They noted that the Dog Star, Sirius, reappeared in the eastern sky just before sunrise after several months of invisibility. They also discovered that the annual flood of the Nile River came soon after Sirius reappeared. They used this event to fix their calendar, and came to recognize a year of 365 days, made up of 12 months, each 30 days long, and an extra dividend of five days added at the end of every year. But they did not allow for the fractional difference of about a fourth of a day, and their calendar slowly drifted into error. According to the famed historian and Egyptologist James Henry Breasted (1865-1935), the earliest date known in the Egyptian calendar correspond to 4236 B.C. in terms of our present-day calendar system. That's 6,247 years ago!

The Mayan people believed the world had been created and destroyed twice before the birth of the era they lived in, and dated the inception of the era as August 13, 3114 B.C. (Gregorian calendar). They reckoned time from this date on two systems, the "long count" and the "calendar round." The long count was based on a 360-day year called a tun, divided into 18 months of 20 days each. The Mayan counting system was based on 20 rather than ten, and years were not calculated in decades but in groups of 20 called k’atuns. Twenty k’atuns (which is equivalent to four centuries) was called a b’aktun. The calendar round simultaneously counted days according to a 260-day and a 365-day year. The purpose of this elaborate counting was to arrive at a especially significant point of coincidence: every 18,980 days or every fifty-two 365-day years, both systems come together.



Speaking of the Mayan calendar, because of the misinterpretation of certain over-zealous doomsayers, it circulated worldwide that the world will end on December 21, 2012, in conformance to the end of a Mayan calendar cycle. It was featured in an episode of the hit TV series The X-Files, and the 2009 science fiction apocalyptic film 2012 was based on this belief.

While the date is regarded as the end-date of a 5,125-year-long cycle in the Mesoamerican (Mayan Long Count) calendar, it is simply the day that the calendar will go to the next b’aktun. The date December 20, 2012 has a Long-Count value of It is not the end of the calendar but is the last day having a b’aktun value of 12. The next day, December 21, 2012 is Such end of b’aktuns occurs approximately every 400 years, and no cataclysmic event has occurred at the end of the 12 previous completions.

The maximum date that can be designated in the Long-Count notation is It corresponds to the Gregorian date of October 12, 4772. This is the “true” last date of the Mayan calendar. So, enough of the doomsday paranoia, it’s creating so much negative energy!


The Greeks and the Romans have a similar calendar system – having a year of 300 days composing of ten months – during ancient times. This was an approximate of the earlier Middle-eastern lunar calendar.

The earliest known Roman calendar consisted of a year of 304 days. The Romans seemed to have ignored the remaining 60 days, which fell in the middle of winter. The ten months composing the calendar were named Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November and December. The last six names were taken from the Roman words for "five," "six," "seven," "eight," "nine" and "ten." Romulus, the legendary ruler of Rome, supposed to have introduced this calendar about 738 B.C.

The legendary Roman ruler Numa added two months, Januarius and Februarius, at the end of the calendar year. To make the calendar corresponds approximately to the solar year, he also ordered the addition of a month called Mercedinus, which had 22 or 23 days. This month was inserted between February 23 and 24 every other year.


During the reign of Emperor Julius Caesar (c. 100-44 B.C.), the accumulated error caused by the incorrect length of the Roman year had made the existing calendar about three months ahead of the seasons. In 46 B.C., Caesar asked the astronomer Sosigenes to review the calendar and make ways of improving it. Acting on Sosigenes' suggestion, the emperor ordered the Romans to disregard the moon in calculating their calendars. He re-divided the year into 12 months of 31 and 30 days, except for the last month, February, which had only 29 days (this was later reduced to 28 days by his successor to the throne, Augustus Caesar) during regular years and one day more during leap years. To realign the calendar with the seasons, Caesar ruled that the year we know now as 46 B.C. should have 445 days. The Romans called it "the year of confusion."

The Romans renamed Quintilis to honor Julius Caesar giving us "July." The next month, Sextilis, was renamed "August" by the Roman Senate to honor Augustus Caesar, adopted son of Julius Caesar. Later, the fifth month became the seventh month and the sixth became the eighth and so on. This is why September, which came from the word Septem, meaning "seven," is now the nine month of the year.

The Julian calendar was widely used for more than 1,500 years. It provided for a year that lasted 3651/4 days. But it was actually about 11 minutes and 14 seconds longer than the solar year. This difference, again, led to a gradual change in the dates on which the seasons began. By the year 1580, the spring equinox fell on March 11, or ten days earlier than it should.


The Gregorian calendar was designed to correct the errors of the Julian calendar. In 1582, on the advice of astronomers, Pope Gregory XIII (1502-1585) corrected the difference between season and calendar by ordering ten days dropped from October 15, 1582. This procedure restored the next equinox to its proper date. To correct the Julian calendar's errors regularly, the pope decreed that February would have an extra day in century years that could be divided by 400, such as 1600 and 2000, but not in others, such as 1700, 1800 and 1900. This is the calendar in use today in most part of the world.

The Gregorian calendar is so accurate that the difference between the calendar and solar years is now only about 26 seconds. The difference will increase by 0.53 seconds every hundred years, because the solar year is gradually getting shorter.

Roman Catholic nations of Europe adopted the Gregorian calendar almost immediately. German states and Protestant countries kept the Julian calendar until 1698. Britain did not change to the Gregorian system until 1752, Russia until 1918, and Turkey until 1927.

In other parts of the world, particularly in Asia, there were also independent origins of the calendar. But it is interesting to note that both Hindu and Chinese calendars were lunar in character slightly more accurate than its Middle-Eastern and European counterparts.
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