Astronomy of the Mayans

The Importance of Astronomy in Mayan Society

​In the Mesoamerican culture, the practice of astronomy was extremely important. To the Maya of Mesoamerica, this ancient science reflected order in the universe and the gods’ place in it. This order reflected an inherent harmony present in their general theological view of the universe. To the Mayans, capturing the essence of time was of the utmost importance. In their cosmology, space and time were inevitably intertwined, as is evidenced by their complex calendar system that combines spatial attributes of the universe, such as animals and plants, with temporal movements of astronomical objects. Although the Mayans never invented water clocks or other specific time-keeping devices, they used the sky as a method of measuring the passage of time.The Mayans believed that celestial events were indicative of communication with the gods. Specific astronomical objects represented certain deities, whose divine lives were portrayed in the daily, monthly, and yearly changes in their appearance. The religious aspect of astronomy was also taken one step further: to astrology. The movement of constellations and other objects across the sky represented a connection between celestial events and human affairs. In other words, the practice of astronomy- in the form of astrology- was believed to have an influence on every Mayan.Finally, probably one of the most tangible and practical benefits of astronomy was on agriculture. The appearance of certain constellations or planets in the sky heralded the planting season. The more they understood the sky, the more assurance there was that the people would not starve. It can be argued on this basis alone that astronomy was a practice which promoted the success of the Mayan civilization.

The Mayan Priest-Astronomers

​The Mayan practice of astronomy was relegated to the ilhuica tlamatilizmatini, or “wise man who studies heaven”. These priest-astronomers had a great amount of power, given the fact that they could essentially ‘predict’ the future. Their knowledge of the patterns of the sky, and of the mathematics that solves more complex patterns, led them to an exalted position in Mayan society. The figure below shows an astronomer with his eye stretched out to the heavens. Priest-astronomers spent the dark hours determining the time of night. Of course, the length of the days varies substantially from season to season, and therefore the astronomers had to be very knowledgeable about the sky in order to know the hour and to predict when the sun would rise again.The Mayan astronomers officially began the day at sunrise, although for some Mayans the day began at either noontime, when the sun was at its highest point, or at sunset. Starting the day at these times may seem strange to those of us conditioned to a western view of time. However, our own time is relatively unusual: we start the day when the sun is almost at its anti-zenith, when it is at its highest point on exactly the other side of the Earth!The priest-astronomers recorded Mayan cosmology in codices, many of which were burned by the Spanish. A few codices remain, and several Spanish historians also recorded basic Mayan cosmology. Codex Vaticanus A is a wealthy source of information on how Mayans viewed the universe. In this document, as in the figure below, it is portrayed as a multi-layered universe consisting of thirteen levels of the heavens and nine layers of the underworld, with the Earth sandwiched in between and belonging to both.

Mayan Cosmology

Michael Coe gives a wonderful explanation of Mayan cosmology in his article on Mesoamerican astronomy (see references). In the center of the universe, the Earth is layer one of the upper world and the underworld. It is conceptualized as a large wheel surrounded by the teoatl, or divine water, which is an ocean that extends to the horizon. The second layer, called Ilhuicatl metzli, is where the moon and clouds reside. The fixed stars lie in the next layer, known as Citlalco, where the deity Citlallicue (“She of the Starry Skirts”) lives. The sun, also known as Ilhuicatl Tonatiuh, occupies the fourth layer, while Venus, the “Great Star,” inhabits the fifth. Layer six is called Ilhuicatl Mamalhuazocan, or “Heaven of the Fire Drill,” which represents an unidentified constellation (perhaps Orion’s Belt). This layer is also where comets (“Stars that Smoke”) come from, and where the fire serpents attend to their duty of bringing the sun from the east to the zenith. The seventh layer is the black or green heaven, fierce with winds or storms, and the eighth layer is blue heaven, which is where dust lies. The next layer, the home of thunder, is called Itztapal Nanatzcayan, or “Where Stone Slabs Crash Together.” Layers ten, eleven, and twelve represent respectively the colors white, yellow, and red. Finally, the last layer, called Omeyocan, is where the dual male-female god, who created space and time, lives.The nine-layered underworld also played a significant part in Maya cosmology. The Milky Way was seen as a road of souls traveling to the underworld, or as the umbilical cord connecting heaven and the underworld to the Earth. As Michael Coe so eloquently states, “The Mesoamerican cosmos was one in constant flux, in which space and time were co-terminous, in which the heavenly bodies moved in fixed layers, and which was in constant peril of cataclysm”.

Mayan Astronomy

Although the Maya appreciated the sky as a whole and its infinite dimensions, they were particularly interested in certain specific astronomical objects. The sun, the moon, Venus, and specific star clusters and constellations were most important. These objects were given the most attention by the priest-astronomers, who spent generations finding the precise paths of these objects across the sky and through the seasons.The most important object in the sky is the sun, which is universally recognized as the prime life-giver on Earth. Tonatiuh, a red eagle with a large and all-seeing eye, was the god associated with the sun. Because of the tilt of the Earth’s axis, the sun appears at different positions in the sky depending on the time of year. This tilt is what produces the seasons experienced on Earth. The Maya accurately calculated times when the sun would rise and set, and even more amazing, they determined the length of the solar year to be 365 days. A tropical year is actually 365.2422 days long, so they were very close in their calculations. Unfortunately, even this small error means that the calendar which they created based on their solar year calculations would be off by approximately one month every 100 years, or by almost a whole six months every 600 years. This is obviously a dramatic difference, but there is evidence that the priest-astronomers continually updated their records and predictions so that the calendar remained accurate throughout the generations.The moon was another object of interest to the Mayans. It was represented by a female deity who had powerful influence on terrestrial events. A waxing moon had the attributes of the beautiful, ideal woman, while a waning moon was considered to be an old female deity who ruled over childbirth. Around 300 C.E., the Mayans began to keep track of synodic lunations, or the interval between successive full moons. A Mayan astronomer calculated that there were exactly 149 moons over a period of 4400 days, which works out to an average lunation of 29.53 days. In the city of Palenque, it was found that there are 405 moons in 11,960 days, which means that an average lunation is 29.53086 days. This is remarkable accuracy, given that the actual average lunation is 29.53059 days.Venus held a particular attraction for the Mayans. It was considered to be connected with the major deity Quetzalcoatl. It was called Xux Ek, the “Great Star,” and the Mayans knew that it is the same object that appears in both the morning and the evening at different times of the year. The priest-astronomers determined the synodic period of Venus (how long it takes to orbit the sun) to be 584 days, which is again incredibly close to the actual period of 583.92 days. When Venus rose in the mornings, it was considered bad luck, and everyone would stay inside their homes and block their chimneys so that the evil light from Venus could not enter. The Mayans also calculated the synodic periods of Mars as 780 days (actual = 779.936 days) and Mercury as 117 days (actual = 116 days), but they seemed uninterested in Jupiter and Saturn, the other bright planets. None of the planets were actually seen as objects different from the rest of the stars, which is unusual considering that they move significantly in relation to the fixed stars.​Certain star clusters and constellations also held special meaning for the Maya. For instance, the Pleiades star cluster appears in the morning sky around planting time, in late April. This meant that the Maya could plan ahead for the planting season, since they could predict the rising of the Pleiades in connection to the appearance of other constellations on the horizon. The Pleiades was called tianquiztli, which meant “marketplace”. There is evidence that the Mayans thought of the Pleiades as being the center of the layer of fixed stars, rather than Polaris, around which the rest of the sky seemingly revolves. The builders of the ancient city of Teotihuacan, below, aligned their main street to the Pleiades. Polaris, or Xaman Ek, was, however, used by travelers to orient themselves on land.​The sky closer to the equator is the most vivid on Earth. Due to the fact that the Earth is a sphere, at a point on the equator people have the opportunity to view all of the constellations visible throughout the world, exactly twice the number visible at either of the poles. Constellations such as the Big Dipper, Orion’s Belt, Cassiopeia, and the Southern Cross were also important to the Maya, although of course they were viewed differently than our western tradition teaches. Festivals were held when the Pleiades and Orion’s Belt rose at sundown and vanished at dawn. Constellations are shown on the border of the Aztec calendar stone, shown below. More captivating objects such as comets were believed to be an even more direct link to the human world. If a comet, or “star that smokes,” appeared in the sky, it foretold the death of a noble person. Often, correlations were made between celestial and terrestrial events, which led to a permanent linkage between humans and gods.​General predictions concerning the placement of astronomical objects in the sky at a certain time were not necessarily difficult to make, considering that there was an entire crew of priest-astronomers who had the sky entirely memorized. However, it is a completely different story to make accurate and specific predictions about certain astronomical events. We have already seen how the Maya determined synodic periods of several objects with amazing accuracy. On the whole, these calculations were simply done by counting, for instance, the number of lunar revolutions in a certain time period. For more complex calculations, however, mathematics was invented.​A prime example of the usefulness of mathematics is in the science of predicting eclipses. Solar eclipses, known as chi’ ibal kin, or “to eat the sun,” were a particular cause for distress among the Maya people. Eclipses can be terrifying events for those who do not understand the basic reasoning behind the occurrence, and so being prepared for them was important. Predicting eclipses is a considerably more complicated task than determining when the sun would rise or set, because it involved correlating the synodic lunations with the solar calendar. In other words, the movement of the Earth, the sun, and the moon all had to be taken into account, which is no small feat for anyone to accomplish. Since the orbital plane of the moon is inclined by 5 degrees to the plane of the Earth’s orbit, eclipses do not happen at every full and new moon. Instead, they occur only when the moon happens to be in the ecliptic plane at the same time that it is at the correct position in line with the sun and Earth.Maya priest-astronomers determined the nodes when the paths of the moon and sun cross, which is every 173.31 days. During this time, eclipses may occur within 18 days of the node. One example of an eclipse table resides in the Dresden Codex, which was written in the eleventh century in the northern Yucatan. The codex is made of ficus tree bark, and the pages are covered with lime for a glossy finish. The glyphs are painted in red and black with a very fine brush. In the eclipse section of the Dresden Codex, two numbers appear quite frequently. The numbers 177, which is approximately the length of six lunations, and 148, or five lunations, are representative of times when eclipses were predicted. The astronomers periodically corrected the eclipse tables, learning from their small mistakes and adjusting the calendars, and so on several occasions we see that the number 178 appears in place of 177. In effect, the eclipse tables consist of columns and rows of the numbers explained above, and in some cases, the eclipse glyph is presented instead. This symbolizes days when an eclipse could be expected, and if one did occur, the number was replaced by the eclipse glyph.

Mayan Mathematics​

The Maya mathematical system on which all this was based was incredibly advanced, and it was developed starting about 500 B.C.E. During the period of the Dark Ages in Europe, the Mayan system was more refined than any in the world at that time. They used a vigesimal, or base 20, number system, which seems foreign to us but is actually quite easy to use with practice. Mayan numbers consist of a series of dots and bars, where dots have a value of one and bars represent five. The numbers one through nineteen, and a series of glyphs representing the number zero, are shown in the picture below.​Our base 10 number system uses a decimal system based on powers of ten, i.e. 1; 10; 100; 1000; and so on. The Mayan system operated on exactly the same principles, except that the ‘decimals’ were based on powers of twenty, i.e. 1; 20; 400; 8000; 160000. An example of simple addition of a large number is shown in the figure below . The Maya also developed the concept of zero, which had immense benefit as a place-holder and vastly simplified basic arithmetic, along with making it possible to do more complex calculations.

The Mayan Calendar

Perhaps the most important application of the Mayan mathematical system was in the development of their calendars. The Mayans were obsessed with numerology, and used many “special numbers” to create their two interconnected calendars. The ritual calendar consisted of thirteen 20-day periods, which totaled 260 days. Although it is unclear exactly why the Maya chose a 260-day calendar, there are several theories. First, the numbers 13 and 20 were two of the numbers considered to have magical powers. Second, by coincidence, two ritual calendar years (520 days) is the same as 3 eclipse half-years (520 days). Finally, although this is a controversial idea, 260 days is approximately the length of human gestation (266 days). It seems likely that a combination of these factors influenced the creation of the 260-day ritual calendar. Each day in a 20-month period of the ritual calendar is represented by a specific animal, plant, or natural force.The Maya also developed a solar calendar, detailing the so-called Vague year. It was 365 days long, consisting of eighteen 20-day periods plus a final five “days without name,” which were considered unlucky. Certain groupings of years held special meaning. For instance, the 52 Vague year cycle represented the time when both the ritual and the Vague calendars would again correlate to the same starting day. In addition, the 52 years were broken down into four 13-year periods, each being thought of as a specific cardinal direction.In addition to this connection between the calendars, there are several other mathematical coincidences that had great importance. There are exactly 146 ritual years in 65 synodic periods of Venus, and similarly eight Vague years are equal to five synodic periods of Venus . The Maya used their knowledge of the sky and their mathematical prowess in a symbiotic relationship, where astronomical cycles precipitated the use of numbers and vice-versa.

Alignment of Mayan Buildings and Temples

It has been recognized by archaeologists that many buildings and temples in Mayan cities have astronomical orientations. This is a field in which there is much on-going work, particularly by Anthony Aveni and his colleagues (see references). Aveni states that “while most Mesoamerican cities exhibit a planned appearance, frequently one or more buildings at a given site seem out of line relative to neighboring structures…One possibility is that astronomical events occurring on or near the horizon could have determined the way a building would face”.​A prime example of astronomical orientation is the so-called Building J at Monte Alban, which was built around 275 B.C.E. This building was constructed in an arrow shape, and Aveni found that five of the brightest stars in the sky would at that time have set approximately at the point of the arrow. In addition, a line drawn perpendicular to the front steps of the building would have pointed directly to the place on the horizon at which the bright star Capella rose. By coincidence, it seems that the appearance of Capella at this position could have heralded the passage of the sun through the zenith (the point directly overhead), since at Monte Alban these events are almost simultaneous. Evidence of this appears in the presence of a zenith tube at the same site, which points directly overhead and effectively finds the sun’s zenith passage. An example of a zenith tube, this one from the city of Xochicalco, is shown in the figure below.​Mayan cities all show signs of astronomical orientation in the construction of buildings. Many of these were actually observatories that had special viewing windows set into the walls. Each window corresponded to a celestial event, for instance the rising of the star Sirius or the setting of the Pleiades. Buildings were purposefully aligned with bright stars like Capella and Sirius, or with Venus, or with the position of the sun’s transit. This diagram of Uxmal shows the astronomical placement of buildings as determined by Anthony Aveni.The fact that the construction of Maya cities depended on astronomy is proof of the intense relationship that Maya had with the sky. The priest-astronomers’ power was indicative of the essence of their duties: if someone can foretell the actions of astronomical objects which are linked to gods, then in the Mayan frame of reference that person is in communication with the deities. Astronomy therefore characterizes many facets of Mayan life, including religious aspects such as connecting the gods’ actions to humans’ lives and practical aspects like measuring time and preparing for planting season. Primarily, though, the Mayan practice of astronomy was actually astrology. The dynamic universe was viewed as the infinite home of the gods, and the work of the men who studied this universe brings a unique perspective to our modern science of astronomy.


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Anthony Aveni. “Possible Astronomical Orientations in Ancient Mesoamerica.” In Archaeoastronomy in Pre-Columbian America, edited by Anthony Aveni. U. of Texas Press, 1975. 163-190.
Anthony Aveni. Skywatchers of Ancient Mexico. U. of Texas Press, 1980.
Michael Coe. “Native Astronomy in Mesoamerica.” In Archaeoastronomy in Pre-Columbian America, edited by Anthony Aveni. U. of Texas Press 1975. 3-31.
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Guillermo Hinojosa. Personal interview. April 25, 2000.
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