Mesoamerican civilizations developed a very intricate and detailed system to identify days and years. This region was home to diverse languages and ethnicities, including the Maya and the Aztec, yet the method for determining the days and years was similar among the heterogeneous communities. These calendars varied in appearance among the different groups in that their sizes, names, and glyphs, among other features, were often different. Despite these variations, the calendars share their origin in addition to many essential features.
Calendars were based on astronomical observations over time and correlated with religion. The first basic feature of the calendar is the sacred day count, totaling 260 days. This sacred calendar correlated with rituals of the gods and has many names among the civilizations, including tonalpohualli in Nahuatl and tzol kin in Yucatec. The days are counted by twenty and by thirteen concurrently. The separate counts are referred to as the veintena and the trecena, respectively. The 260-day cycle is used along with the year cycle of 365 days, which is also called the secular calendar. This was used to determine agricultural patterns and seasons. Here the year is divided into eighteen months comprising twenty days each with a final month of five fateful days. The names of the years come from a combination of the two cycles. These names were not repeated for a cycle of fifty-two years. Because of the long lapse between year names, many Mesoamerican cultures believed that historical events would reoccur every fifty-two years. This system, comprising combinations of days, months, and years, serves as the basis for Mesoamerican calendars. These calendars include those of the Maya, Aztec, Zapotec, Quiche, Tikal, Mixe, and Tilan-tongo among many others, the most prominent one being that of the Aztec.
The Sun Stone, a widely known artifact with some of the features of the Aztec calendar, was recovered in Mexico in 1790. Antonio de León y Gama was the first person to attempt to uncover the true meaning behind its glyphs after its discovery. Some of his research has been contested and expanded upon by later researchers such as Alexander von Humboldt and Ezequiel Ordóñez, yet many of his findings are still accepted in the early twenty-first century. While many people consider the Sun Stone to be the Aztec calendar, it is important to note that this monolith was actually a commemorative stone; it represents the days and the stages of the sun but it is not the calendar. The real Aztec calendar does follow the basic pattern set forth by that of the other Mesoamerican calendars. The Sun Stone represents the glyphs of the twenty days and the four previous ages, or suns, and the current age. The twenty days surround the glyphs that represent the ages in the center of the artifact. The days should be read counterclockwise beginning with Cipactli, the crocodile. The other nineteen days are represented by Ehécatl (wind), Calli (house), Cuetzpallin (lizard), Cóatl (serpent), Miquiztli (skull), Mázatl (deer), Tochtli (rabbit), Atl (water), Itzcuintli (dog), Ozomatli (monkey), Malinalli (herb), Ácatl (cane), Océlotl (jaguar), Cuauhtli (eagle), Cozcacuauhtli (vulture), Ollin (movement), Técpatl (knife), Quiahuitl (rain), and Xóchitl (flower). This stone measures 141.73 inches in diameter and its proper positioning is horizontal, not vertical, as previously believed.
Edmonson, Munro S. The Book of the Year: Middle American Calendrical Systems. Salt Lake City: University of Utah Press, 1988.
Malsmström, Vincent H. Cycles of the Sun, Mysteries of the Moon: The Calendar in Mesoamerican Civilization. Austin: University of Texas Press, 1997.
Matos, Eduardo, and Solís, Felipe. The Aztec Calendar and Other Solar Monuments. Córdoba: Conaculta-Instituto Nacional de Antropología e Historia, 2004.
Amanda Lais Gray