Yesterday was the vernal equinox, one of the two moments in the year when the Sun crosses the celestial equator. Days are as long as nights and so the world can be said to be balanced.

I was at the San Francisco Exploratorium as part of their Chichen Itza event. A team of people were broadcasting from the pyramid at Chichen Itza to San Francisco. The Sun rose in the sky and at the moment of the equinox itself, the alignment of the pyramids cast the shadow of a serpent upon one of the staircases.

I was there speaking and answering questions about the Mayan Calendar system.

My favorite analogy for the structure of Mayan time is wheels within wheels. The Mayans like us, were attentive to the cyclical nature of most events. The cycles of the Moon, the Sun and the Seasons were like great wheels in slow revolution.

The Tzolkin calendar, or religious calendar, consisted of 13 numbered days and 20 named days. These two wheels turning together made up a 260-day calendar.

The Haab or civil calendar was 18 months of 20-day periods along with an extra 5 days for a total of 365 days, not unlike our calendar.

A specific day could be named with both its Tzolkin name and its Haab name. Because of the different lengths of these calendars, a day was unique within a 52-year period. This 52-yr period was the Mayan Calendar Round. Every 52 years the Mayans waited to see if the Gods would choose to renew their world or to destroy it.

For longer periods, yet another calendar, The Long Count, was used. The smallest wheel in the Long Count was a period of 20 days. The next was 18*20 (360) followed by 20*18*20, followed by 20*20*18*20, followed by 13*20*20*18*20. This longest period of days amounted to just over 5,000 years and is known as a Mayan Era. It was the longest period that had a direct effect on human affairs although longer periods were known and named by the Maya, including a cycle of 63 Million years known as the alautun.

From historical records, the beginning of the last Mayan era can be dated to 3114 BC. Counting forward, this places the end of the current Mayan era in December of 2012 AD.

Besides these well-known calendars, the Mayans had many others. It seems that the Mayans were intoxicated by both Time and Mathematics. One of my favorite cycles is one of 819 days (a little over two years) which has an unknown name or purpose.

The 819 day cycle is the product of three different smaller cycles: A 7-day cycle which was the Mayan Representation of Earth, a 9-day cycle which was the Mayan number of Heaven or Gods (and was represented by the Nine Mayan Lords of the Night) and, finally, a 13 day cycle which represented the Inferno. (It seems that the number 13 has been universally unloved.)

The diagrams we had prepared to help people visualize all of this was a large assembly of gears. The Universe depicted as a conjunction of all these different cycles, as a ticking mechanism whose parts, when they align, can signal transcendence or catastrophe.