Remember Y2K? Or that in August, 2003, Mars was supposed to be as large as a full Moon?
Urban legends such as these become widespread from people simply not asking "Are you sure?" or looking into the
topic and learning more before making a decision. Now a somewhat recent urban legend is generating interest due in large part to statements made by
doomsday predictors, news media, those who profit from Scientific Illiteracy of others, and obviously Hollywood.
The Long Count This month, some folks would have us believe that the world as we know it will
come to an end, or, depending on the source, some sort of "cosmic event" will happen. Whatever the suggested event
is, it is supposed to happen when the Mayan calendar, based on a numbering system called the Long Count, or Long Cycle,
reaches the last day of the current counting cycle. One belief is that this last day is on December 21, 2012, the date
of the December solstice. The date for this event was determined by adjusting for leap years and the modern Gregorian
calendar and then literally counting the days since the current Long Count cycle began.
The Long Count system is a base 20 numbering system that is very accurate in terms of tracking
historical events or for counting days to future events by counting forward from the first day. The count involves a
series of numbers representing various lengths or periods of time measured in days. As with any calendar, when the
last day is reached, the calendar in a sense is reset back to day 0, or the calendar counting starts all over.
The Mayans used a variety of calendar counting methods, with the Long Count used specifically for
very long periods of time (e.g., 5,000 years). When written horizontally, there are a series of five numbers separated
by periods that make up the day number. Starting at the beginning of a counting cycle, 0.0.0.0.0, each unit increases by
one day (kin) using base 20, except for the Uinal, which changes at 18 rather than 20. The numbers are usually written
vertically from the Baktun down to Kin, and represent the number of days. Twenty Kin
equals 1 Uinal, 20 Uinals equals 1 Tun, 20 Tun equals 1 Katun, and 20 Katun equals 1 Baktun. When each value reaches its
maximum number, it resets to 0 while the value to the left increases by one. For example, the first day of the count
would be 0.0.0.0.1, the second day 0.0.0.0.2, and so on. When the right-most space reaches 19, the day after 0.0.0.0.19,
or the 20th day since starting the count, would be: 0.0.0.1.0. The 21st day = 0.0.0.1.1, the 22nd day = 0.0.0.1.2, and
so on. A way to help students picture how the numbers change could be to have them use a clicker-type counter. Have
students observe how the numbers change as the ones column reaches nine, then resets back to 0, while the tens column
changes to one. Each time the ones column reaches the count of 10, it resets to zero and the next column, tens,
increases by one. This continues until the tens column reaches 10, and then it resets to zero and the 100s column
increases from zero to one, and so on. In the Mayan Long Count system, they used base 20 instead of base 10, so numbers
changed when the count reaches 20, rather than 10.
An interesting side note to the counting system is that the ancient Mayans knew that it took
approximately 365 days for the Sun to return to its same location. This is shown by having the Uinal column stop at 18.
Each time Uinal reached 18, one year had passed. When the Kin count reaches 20 for the 20th time, there will be 18 Uinal,
and 18 x 20 = 360 days. Close enough!
Try, Try, Try, Try Again In Mayan mythology, there were three attempts at creation of the Earth and life on the Earth before the fourth,
and current Long Count started. Using the modern Gregorian calendar, it has been determined that the current Long
Count started 5,135.35 years ago on August 13, 3134 BC, or by using the Mayan system, 12.0.0.0.0. Each creation (one Long Count cycle)
represented a span of 14 Baktuns, and we are now nearing the end of the 13th Baktun, which has been calculated to end on
December 21, 2012. In terms of Mayan mythology, there is no mention of any event, cataclysmic, cosmic, or otherwise, at the end
of any Baktun. Nevertheless, end-of-the-world promoters and others have created an urban legend about this with the suggestion
that on this particular date something will happen.
This predicted event has been attributed to an alignment involving the Sun's position along the ecliptic
path on the December (winter) solstice intersecting the plane of the galaxy, the galactic equator. On any December (winter) solstice,
the Sun is at a specific celestial coordinate position of 23.5° south and 18 hours of right ascension (18 RA. This is
the Sun's southern most distance south of the celestial equator.
Currently, the Sun is located within the constellation of Sagittarius
the Archer on the December (winter) solstice as this graphic shows. (The Sun’s position on the December solstice of 2012.
The galactic equator is the blue line within the Milky Way, the slightly brighter area on either side. The ecliptic is shown by the green line.)
However, due to a slow Earth motion called precession, the stars relative
to the view from Earth have shifted enough so that at the start of this current Mayan Long Count cycle, the Sun was in the constellation
of Capricornus the Sea Goat on the winter solstice. Additionally, the intersection of the galactic equator with the ecliptic has also
shifted such that it now intersects the ecliptic at the winter solstice point. However, at the beginning of this Long Count that
intersection was to the east of the current winter solstice position.
Precession is often described as a wobble-like motion of the Earth around its axis. Like a spinning top that is
slowing down, the poles of the Earth spin in a circle around the axis of rotation. Earth completes one precession in approximately
26,000 years. But unlike a top, it will not stop spinning and fall over. As the Earth spins through a precession cycle the North Pole
and South Pole of the Earth trace out a circle amongst the stars. This means that any star on or near the apparent circle the poles
draw in the sky becomes a pole star.
Currently the star marking the end of the Little Bear's tail, Polaris is the North Pole Star,
while the southern hemisphere has no South Star. With regard to the constellations marking seasons, their celestial coordinates will
change over time during a precession cycle such that the location for the winter solstice, for example, has moved from Capricornus west
to Sagittarius. What this means is that approximately every 26,000 years or once every precession cycle the Sun returns to the same
location. In other words 'we have been there and done', and nothing has happened in the past. So unless there is something extra special
about this particular one, there will be no cosmic calamity on December 21st 2012.
 "Click on this image to see it full size")
