The Chinkultic Disk: Truth and Fiction "Many Mesoamerican peoples saw in the ball game a metaphor for the movements of the heavenly bodies, particularly the sun, moon, and Venus. The ball itself may have been understood as the sun journeying in and out of the Underworld, seen as the narrow alley of the ball court." . (Miller and Taube, The Gods and Symbols of Ancient Mexico and the Maya)     The Chinkultic (La Esperanza) disk was one of the first Maya ball court markers discovered.  Perhaps because it is housed in the Museo Nacional de Anthropolgia in Mexico City, it is also one of the best known. The  disk shows a ballplayer in a characteristic pose, kneeling to strike the ball with the heavy yoke about his waist and thighs.  View a larger image of the disk

The inscription around the edge of the Chinkultic ball court marker begins directly above the ball player's head with the  long count  9.7.17.12.14.  According to the GMT correlation accepted by most Mayanists, this date corresponds to about May 21, 591 AD in the European (Gregorian) calendar.
 
 

The last glyph in the text (the head of an aged deity called "God N" by scholars) is a common verb in the inscriptions, marking the rituals performed when a new monument was erected. It reads t'ab, "was blessed", "was dedicated".  May 21, 591 AD appears to be the date on which the ball court was dedicated, preparing it as a sacred site for ritual performances.  This was a particularly auspicious time to dedicate the court: The sun was near the zenith, and Venus was near maximum western elongation.

Chichen Itza.  Ball game sacrifice ritual. Note "blood snakes" from decapitated captive warrior, and skull in the ball. (Schele)

• On May 21, 591 AD, Venus was the Morning Star, 45.6 degrees west of the sun. The maximum western elongation in each synodic period of Venus varies slightly, between 45 and 47 degrees from the sun. Venus moves slowly near maximum elongation, and was thus near the maximum for several weeks in May 591 AD. The elongation was actually greatest on May 13, 591 AD, when Venus was 45.9 degrees west of the sun. On May 21, it had fallen only about 1/3 degree from the maximum, less than the diameter of the full moon.

• The date of Zenith passage of the sun depends on the latitude of the observer. On May 21, the sun was directly overhead at noon at about 20 degrees N latitude, in the central Yucatan. Chinkultic is 16 degrees 15 min N.  At this latitude, the sun was a bit less than 4 degrees from the zenith on May 21; zenith passage actually occurred on May 6.

May 21, 591 AD was not exactly the time of  either the zenith passage or the maximum elongation of Venus, but it is reasonably certain that the scribes had these events in mind when they chose a dedication date for the Chinkultic ball court. In the tropics, zenith passages of the sun occur twice a year, in May and July in the Yucatan.  According to the Books of Chilam Balam, at the time of the conquest  the beginning of the solar year fell on July 16 in the Julian Calendar then used by the Spanish. (July 16, 1500 AD is equivalent to July 26, 1500 AD in the Gregorian Calendar now in use).  This date was used throughout the Yucatan, even though it was the exact date of the zenith passage only at 19 degrees 30 min N.  It seems likely that the Chinkultic scribes similarly chose conventional dates for the zenith passages marking the course of the year, based on observations in the central Yucatan rather than at Chinkultic.

19 degrees 30 min N is the latitude of Edzna, an important centre in the central Yucatan. Vincent Malmström argues that the solar year was fixed in the Classical period by zenith observations at Edzna. In 591 AD, the date of the spring  zenith passage at Edzna was May 19 (Gregorian). This is very close to the date on the Chinkultic disk.

The rare coincidence of a zenith passage and maximum elongation of Venus would almost certainly have seemed particularly significant. The ball on the Chinkultic disk is inscribed with the head of Hun Ahaw, one of the Hero Twins who defeated the Lords of Xibalba, the underworld, making creation of the present world possible. In pre-Conquest texts, the twins were associated with the sun and Venus. According to Linda Schele, the ball player on the disk wears the "white bone snake" headdress of an underworld Lord, the "God of Zero".
 

Copan ballcourt marker.  Ball players   impersonate Hun Ahaw (left) and God of Zero (right) (Schele)

In the post-conquest Popol Vuh of the Quiche Maya, the twins played ball with the Lords of Xibalba. Hunaphu (the Quiche equivalent of Hun Ahaw)was decapitated, and his head substituted for the ball  before he was resurrected by his brother.  Dennis Tedlock,  translator and commentator on the Popol Vuh, interprets the hero twins myth cycle as an account of the apparitions of Venus. The heliacal rise of Venus, when it first rises in the morning sky in the east, marks the direction of sunrise and rebirth. Cosmical rise, when Venus  rises at sunset in the west, is associated with evening and death. The period of invisibility between disappearance in the west at sunset and heliacal rise in the east marks Venus' sojourn in the underworld.  Maximum elongation may have been seen by the Chinkultic scribes as the moment when Venus reversed its course and began its "fall" into Xibalba.

The Sport of Life and Death: The Mesoamerican Ball Game (Introduction in animated format. Very nice)
The Ball Game (Brief illustrated discussion with a Bibliography of Ball Game Sources and Links)
The Ball Game (Nice collection of illustrations of artifacts associated with the Mesoamerican ball game)
The Book of the People: Popol Vuh  by D. Goetz and Sylvanus Griswold Morley at  Sacred Texts
Ballcourts : The Chasms of Creation, by Mary Ellen Gutierrez (Scholarly article from the Texas Notes Archive 
The Divine Patrons of the Maya Ball Game by Alexander Tokovinine (Scholarly article from Mesoweb)
 
 
 

The mythology and ritual of the ball game is described in "Gaming  with the Gods", a chapter in Linda Schele, David Freidel, and Joy Parker's lively and readable account of the Maya world view, Maya Cosmos: Three Thousand Years on the Shaman's Path, William Morrow & Co., 1993.

The definitive translation of  the Popol Vuh, including extensive notes explaining astronomical references in the text, is Dennis Tedlock's  Popol Vuh: The Mayan Book of the Dawn of Life, (Rev.), Simon and Schuster, 1996.