As I wrote in my previous post, I was listening to the audio book Unlocking the Secrets of 2012 by John Major Jenkins. One of the most important things I think he brings to his discussion of the December 21, 2012 Mayan date is that he views it through the astronomical perspective of the Mayans.
As you may know, the Mayan calendar is really several calendars running at once. There is the 260-day cycle that is based on the number of days between conception and birth in humans, as well as the length of time between planting a seed of corn and harvest. It was also the number of days between absolute solar zenith in the city where the 12/21/12 calendar date was birthed -- Izapa, Mexico. There is a 52-year cycle, there are lunar cycles and Venus cycles, and other various cycles, but the cycle ending that is coming up is one of the longer ones, the Great Cycle, circling around every 26,000 years or so.
What is it that they're measuring? The Mayans were extraordinary astronomers, and they were able to predict over 2,000 years ago that the path of the Winter solstice sun would intersect with the great rift of the Milky Way on December 21, 2012. What's so important about that astronomical event? More on that next time.