From another thread, because I felt it deserved a thread of its own:
I'd like to add some details about the Mayan calendar and the translation to Gregorian dates, something I have posted on before.
Many in the New Age Community mistakenly think the Mayan calendar ends in 2012. However, just as the Gregorian calendar did not end at the conclusion of 1999, neither does the Mayan calendar end at the conclusion of Long Count 12.19.19.17.19. It will simply roll over and start the next cycle at 13.0.0.0.0.
As for which Gregorian date this will happen is open to some conjecture. By far the most commonly accepted translation by Mayan scholars is that Mayan date 13.0.0.0.0 correlates to Gregorian date December 21, 2012. This is according to the Goodman-Martinez-Thompson (GMT) correlation constant of 584283. Another less popular correlation constant is 584285, in which Mayan date 13.0.0.0.0 correlates to Dec 23, 2012.
I find this to be a useful calendar tool:
http://www.pauahtun.org/tools.html
just be careful about which correlation constant you use
Also, I am not aware of any planetary alignment at that time. However, Jenkins claims that on that date, due to the precession of the winter solstice, the Sun will be in conjunction with the intersection of the ecliptic and the plane of the Milky Way. Perhaps this is the "alignment" being referred to. I haven't verified whether Jenkins's calculations are correct or not, nor have I yet seen any other verification. Perhaps Phil Plait can comment on this point.
In any case, there is a lot of nonsense being published about the Mayan calendar, both in print and on the web, and I would especially steer clear of two major nutjobs, Arguelles and Calleman.
Perhaps it's time to gather all my notes on this entire topic and write an article and FAQ for my website. There's certainly quite a bit more I could say about this, even without my notes. I only have nine years to procrastinate, though.
To summarize:
Mayan date 12.19.19.17.19 = December 20, 2012
Mayan date 13.00.00.00.00 = December 21, 2012 (winter solstice)
I'll second that prediction.
I'd like to add some details about the Mayan calendar and the translation to Gregorian dates, something I have posted on before.
Many in the New Age Community mistakenly think the Mayan calendar ends in 2012. However, just as the Gregorian calendar did not end at the conclusion of 1999, neither does the Mayan calendar end at the conclusion of Long Count 12.19.19.17.19. It will simply roll over and start the next cycle at 13.0.0.0.0.
As for which Gregorian date this will happen is open to some conjecture. By far the most commonly accepted translation by Mayan scholars is that Mayan date 13.0.0.0.0 correlates to Gregorian date December 21, 2012. This is according to the Goodman-Martinez-Thompson (GMT) correlation constant of 584283. Another less popular correlation constant is 584285, in which Mayan date 13.0.0.0.0 correlates to Dec 23, 2012.
I find this to be a useful calendar tool:
http://www.pauahtun.org/tools.html
just be careful about which correlation constant you use
Also, I am not aware of any planetary alignment at that time. However, Jenkins claims that on that date, due to the precession of the winter solstice, the Sun will be in conjunction with the intersection of the ecliptic and the plane of the Milky Way. Perhaps this is the "alignment" being referred to. I haven't verified whether Jenkins's calculations are correct or not, nor have I yet seen any other verification. Perhaps Phil Plait can comment on this point.
In any case, there is a lot of nonsense being published about the Mayan calendar, both in print and on the web, and I would especially steer clear of two major nutjobs, Arguelles and Calleman.
Perhaps it's time to gather all my notes on this entire topic and write an article and FAQ for my website. There's certainly quite a bit more I could say about this, even without my notes. I only have nine years to procrastinate, though.
To summarize:
Mayan date 12.19.19.17.19 = December 20, 2012
Mayan date 13.00.00.00.00 = December 21, 2012 (winter solstice)
We only have 9 years left! OH NO!!! 
