Not everyone automatically thinks about calendars as forms of time-keeping methods.
Although they do not track the hours, minutes and seconds, calendars help us tell time in larger units of days, months and years. Calendars certainly have an extensive past – their history begins in Egypt during the early 2nd millennium B.C. Early Egyptians devised the calendar very accurately, with precisely 365 days, to map the times when the Nile River would flood. Over the years, calendars were developed by different people. This post on the Alarm Clock Blog will explore those types and their histories, including the Gregorian calendar, which is the standard calendar used today.
Before explaining the different calendar types, it is important to explain the three calendar formats that are incorporated into these types:
- The lunisolar calendar format is based off the solar time of year and the moon phase. If the year is considered a sidereal year, it will show a constellation predicted to appear near the full moon, but if it is considered a tropical year, it will instead yield a season.
- A lunar calendar is one that is based on the lunar cycles, however most lunar calendars have a connection with lunisolar calendars.
- Quite oppositely, a solar calendar is dependent upon the position of the earth in accordance with the sun. Based on the position of the sun passing the equator, there are only seasons in this calendar.
In 500 BCE, the Chinese developed the traditional Chinese calendar, which was in a lunisolar format. This calendar had actually originated back to the late 2nd millennium in the Shang Dynasty, just a short time after the Egyptians crafted the first calendar, but was repeatedly revised. Chinese zodiac signs play a role in this calendar also. With 12 months in a year, each year is represented by an animal; for example, the year 2010 would be considered the Year of the Tiger.
The Chinese calendar differs from the calendar we know today in its counting sequence of sixty-year periods. In this system, time was counted forward from the year we know as 2637 BCE, which was the year Emperor Huang-di served his 61st reigning year and when he invented the calendar. Every 19 years, the Chinese calendar mysteriously syncs with the Gregorian system we are familiar with; a person born in one of these years would find their 19th and 38th birthdays to be the same date on both a Chinese and Gregorian calendar.
Still used today in Oaxaca, Mexico and areas of Guatemala is the Mayan calendar.
Based on a complex system of almanacs and calendars, this calendar was developed in the 6th century B.C. The calendar which is most studied by scholars is the Tzolkin, a version of the most important 260-day calendar in their system. This system included a wide array of astronomical observations, cycles and events. After carefully studying and analyzing these events, the Mayans would then make linear connections between those events and time. When drawn, the Mayan calendar appears much different – each of the 20 days in a month has its own name, number and glyph symbol. Although their calendar is based on 365 days, the seasons are inaccurate due to omission of a quarter day on the tropical year. The Mayan calendar divides the year into 19 months, each having a name and symbol, with the last month lasting only 5 days. Referred to as “Wayeb,” this five-day month is supposed to be a potentially terrible time for disaster, due to the boundaries of the vengeful underworld being broken.
Another ancient calendar is the Julian calendar, created by Julius Caesar in 46 B.C. Until the mid-20th century, the Julian calendar was the standard acceptable format in most countries. Similar to the calendar we know today as a standard, the Julian version included a 365-day year with 12 months and a leap day included every 4 years in February. Until this calendar was used, a previous similarity was the Roman calendar, a lunar format consisting of 301 days, with 60 unassigned days that indicated winter days. While the Roman calendar was replaced completely, the Julian calendar is still used today by the inhabitants of Mount Athos and the Berbers of North Africa. Until about 8 A.D, this calendar had a long history of leap year errors; instead of implementing a leap year every 4 years appropriately, the creators of this calendar used the leap year every 3 years.
The simplified calendar we are familiar with today is the Gregorian calendar. Accepted in nearly every country as the standard, this calendar is referred to as the “civil calendar.” Named after and invented by Pope Gregory XIII, the calendar was developed in 1582. The Gregorian system is the result of 2 calendar modifications, which were discovered by Aloysius Lilius. After reforming the Julian calendar in regards to the time leading up to Pope Gregory XIII’s time, along with reformation of the lunar cycles relating to the dates of Easter, Lilius devised a more accurate calendar that became widely accepted. Many countries still used the Julian system, but when they discovered discrepancies between their days with the Gregorian calendar, they chose to accept this new standard that ruled the business world. With 365 days divided into 12 months, and 1 additional day every 4 years in February, the Gregorian calendar is a solar format.
There are also calendars related to certain religions. One example is the Islamic calendar, which is used in Muslim communities to apply dates to events. In the year we know to be 638 A.D, the Islamic calendar was created by Umar ibn Al-Khattab, a close friend of the Prophet Muhammed. Events recorded on this calendar are labeled as AH or BH, respectively referring to after the Hijra or before the Hijra. A very important event in Islamic history, the Hijra is the name given to the journey of Prophet Muhammed when emigrating to Medina from Mecca. This calendar includes a year of 354 or 355 days, divided into 12 months. Each month is also divided into 7 days. Since the Islamic calendar is not synced with seasons, it is a completely lunar format.
Another example of a special calendar used by a specific following is the Hebrew calendar, used by many believers of the Jewish faith for determining the dates of Jewish holidays. Dating back to the 2nd millenium B.C, the Hebrew calendar is a lunisolar format. There is speculation between whether Moses or other religious figures created the original template for this calendar. Used today to determine the appropriate times for sacred religious texts to be read from the Torah, the calendar’s uses are only related to the beliefs of the Jewish faith. In Israel, the Hebrew calendar is also used as a standard for timeframes relating to agriculture.
There are several other sub-types of calendars that preceded some of these examples, as well as sub-types that are meant to be used in accordance with one calendar for a specific purpose, such as planting or harvesting.
Whether used for business, religious practices, predictions or simply to know what day it is, some form of calendar is used by every person to identify the larger time increments of days, months and years.
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