The Venus Round
The calendar system based on the cycle of 260 days in combination with the day count has many remarkable properties, none more so than the fact that it allowed the Maya to very accurately record the cycles of other planets. Venus was particularly important to them and was regarded as the celestial equivalent of the god Quetzalcoatl/ Kulkulkan. A whole table of calculations regarding the cycles of Venus can be found in one of the three surviving Mayan books, the Dresden Codex.
The Maya were able to work out that it was possible to follow multiple cycles of time simultaneously by using the 260-day cycle as the common factor. With Venus, which has a 584-day synodic period, they were able to calculate that 146 Tzolkin rounds would be exactly equivalent to sixty-five Venus revolutions. This meant that 37,960 days elapsed between incidences of Venus rising as the morning star. This took place on 1 Ahau, its sacred Tzolkin day. This was also exactly 104 years of their 365-day Haab calendar, or two calendar rounds.
These calculations are remarkable and would have taken many generations of observation to establish. For naked-eye astronomers, subject to the vagaries of weather, to record these events so accurately was a singular achievement. Without the elegance of the vigesimal calendar, especially in the form of the Long Count, none of this would have been possible. At the peak of their culture, the astronomy of the Maya was at least as developed as that of the Spanish invaders, and they did not have the advantage of the invention of the telescope; it is thought that the Maya tracked the stars by watching their motions reflected in specially built pools in their ceremonial centers. Their extraordinary calendar system made this remarkable knowledge possible.
The Maya generally considered Venus's first appearance in the morning sky an evil omen but a good day for warfare. There is evidence that they planned “star wars” to coincide with these specific astronomical events and would conduct raids on neighboring cities.
The fact that so many planetary cycles can be harmonized by using a combination of the Tzolkin and the Long Count strongly suggests that the Mayan vigesimal counting system is tapping into a more fundamental resonance with the laws of nature than the decimal one. It has long been established in astronomy that the orbits of the planets closely correspond to whole-number harmonics. This principle is called Bode's Law. It can be used to predict where a planet's orbits is likely to fall and also what the mass of a planet is likely to be. The Mayan calendar seems to articulate a similar principle. The fact that so many planetary cycles have ratios that fit so well into the calendar system far exceeds the bounds of probability.
The Mayan Zodiac
Another example of these magical number ratios is found in cycles the Maya were unable to track because they are not visible to the naked eye. For every twenty Venus rounds, there are twelve conjunctions of Uranus and Neptune. This cycle also equals exactly 2,080 Haab years or forty calendar rounds. It also makes one zodiacal age in the Mayan thirteen sign zodiac. In the Paris Codex, one of the surviving Mayan books, researcher Linda Schele has identified a Mayan zodiac dividing the sky into thirteen signs, rather than twelve as used in western astrology.
Other Cycles of the Calendar
Within the Long Count inscriptions even more cycles were recorded. A special glyph was used to record the phase of the moon. There was a nine-day cycle that corresponded to the nine lords of the night and a seven-day cycle that probably corresponded to gods of the earth. There was also an 819-day count that was added at Palenque around
