The Mayan calendar, which originated as early as the 6th century BCE, was based in part on the traditions of earlier Central American cultures, including that of the Olmecs. The Mayans made careful observations of the moon, sun, and stars. From their astronomical studies they developed a complex calendar system that allowed them to perform calculations to determine what day of the week a future date would land on.
Despite lacking reliable instruments to establish accurate lengths of time, the Mayans used fixed reference points and matched multiples of lunations, calendar cycles, and eclipse intervals to discover the length of the tropical year and the lunar synodic month. Lacking a system for expressing fractions, they used multiples to express that the length of the tropical year as 365.242 days and the length of the lunar synodic month as 29.530864 days. Whereas the solar calendar used by Western nations such as Rome or Egypt disregarded the phases of the moon, the Mayan calendars included them. With the correlation of two different cycles, the Mayans determined dates of solstices and equinoxes to an accuracy of within one day.
The Mayan calendar system employed a complex correlation of two cycles, the Haab and Tzolkin, to make the Calendar Round. Each day and month had a name or number and a god associated with it to give the day fortune or misfortune. Mayan priests would weigh gods against one another, and their activities depended on whether or not the day would hold fortune or misfortune.
The Haab calendar, based on solar observation, structured the planting of agricultural crops. It consisted of 365 days, organized in 18 named months (Pop, Uo, Zip, Zotz [Zodz], Zec [Tzec], Xul, Yaxkin, Mol, Chen [Ch’en], Yax, Zac, Ceh, Mac, Kankin, Muan, Pax, Kayab, Cumku) with 20 days each plus Uayeb, a 5-day period. The name of each day began with a number from 1 through 20, followed by the name of the month. For example, the calendar would begin with 1 Pop, 2 Pop, 3 Pop, and continue until 20 Pop at which the next month would begin with 1 Uo, 2 Uo, 3 Uo, and continue on through the 18 month names. During the 5 days of Uayeb, considered phantom days or days of misfortune, all activity was avoided while the people waited for them to pass.
Although the Mayans knew the year was 364.25 days long, this calendar ignored that fact and drifted off 6 hours per year. Due to this, the New Year occurred at different times with different points recognized as the beginning. The Haab calendar consists of a circular view of time in which history repeats itself. In the case of the Haab, history repeated itself every 20 years. According to this, the past, present, and future blend together since all will eventually repeat.
Mayans used the Tzolkin calendar ceremonially, setting the dates for feasts, when to wage war, and when to offer sacrifices. The Tzolkin consisted of 260 days, or 20 periods of 13 days. Days were labeled by using 20 named days and 13 numbers. The 20 named days consisted of Imix, Ik, Akbal, Kan, Chicchan, Cimi, Manik, Lamat, Muluc, Oc, Chuen, Eb, Ben, Ix, Men, Lib, Caban, Ezznab (Adznab), Cauac, Ahau. Each of the 260 days had its own unique name through keeping the named days in the same order and counting them off from 1 to 13. After 13, the numbers restart at 1 and the names later restart after Ahau, creating a cycle of new combinations. For example, the calendar would start with 1 Imix, 2 Ik, 3 Akbal, continue to 13 Ben, then the numbers would start over with 1 Ix, 2 Men, 3 Lib, and continue until the names repeated with 7 Ahau, 8 Imix, then continue until the numbers repeated again with 13 Cimi, 1 Manik, and 2 Lamat. This allowed for the calendar to have no official beginning or end until the end of the 260 days, following a cyclical view like the Haab.
The combination of the Tzolkin and the Haab was called the Calendar Round and consisted of 52 years. The day the year began was the year bearer and gave fortune or misfortune to the year. Only 4 days could be the year bearer: Kan the maize god and Muluc the rain god both predicted good years while Ix and Cauac both predicted bad years. Neither the Tzolkin nor the Haab counted the years, since a date in the combined Haab and Tzolkin would not be repeated for 52 years (beyond the average life expectancy).
The Long Count calendar held a linear view of time and allowed for the Mayans to record the time and events. This allowed for the recording of time and events every 20 years on carved stelae by using pictorial inscriptions that included dots and bars. The earliest stele known is correct up to a few hours (date 292 CE, stele no. 29). The calendar measured from the mythological beginning of time (in the Gregorian calendar, 3114 or 3113 BCE) to a then-distant point in the future (Gregorian calendar 2011 or 2012 CE). The 1-year difference in the Gregorian calendar is related to the question of the year 0 between 1 BCE and 1 CE.
Each day in the Long Count calendar is named in terms of two smaller cycles, a cycle of numbers from 1 through 13 and a cycle of 20 names used in a fixed order. The cycle’s number system, based on 20, consists of 360 days (a tun, or a year). A katun equals 20 tun, and because of the layout, a katun could end only on the day of Ahau. Each katun had a ruling god that yielded the same powers each time a katun returned, but only three katuns held good prophecies.
A baktun consists of 20 katuns (400 years), and a complete cycle consists of 13 baktuns (5,200 years). The name of this cycle is based on Ahau, the date on which the katun ends. The cycle begins with 13 Ahau and drops 2 with every Katun until the cycle repeats itself (13-11-9-7-5-3-1-1210-8-6-4-2-13). What is considered a Great Cycle is completed at the end of all 13 cycles; it’s said that all things will then cease to exist (2011 or 2012 CE) and a new world will be ushered in with the next Great Cycle.
See also Aztec Calendar; Egyptian Calendar; Roman Calendar; Eclipses; Phases of Moon; Measurements of Time
Aguiar, W. R. (1978). Maya land in color. New York: Hastings House.
Thompson, J. E. S. (1954). Rise and fall of Maya civilization. Norman: University of Oklahoma Press.