Who are the Maya?
An indigenous group of populations in Central America – from Honduras, Belize and Guatemala to Mexico and El Salvador – they flourished for centuries until the arrival of Europeans in Latin America. Some of their texts, their calendar, their architecture and examples of their urban planning survived a purge by church and government officials. Millions of ethnic Maya still live in the region, many speaking one of several Mayan languages.
What's their calendar, and what does it say about 21/12/2012?
The Mayan calendar is cyclic – unlike our version of time, it doesn't have a concrete start and end. When one cycle ends, another begins – which is why experts scoff.
What's supposed to happen Friday?
According to the Maya, nothing apocalyptic. Some indigenous cultural groups are holding ceremonies to mark the change of cycles, but that's as dramatic as it gets.
Doomsayers, however, believe the world will end but how it will end depends on whom you ask: The Earth could be smashed to bits by a giant asteroid, collide with something called Planet X, or be burned to a crisp by super-sized solar flares.
Is all this end-of-the-world talk really part of Mayan culture?
No. This calendar was appropriated, Concordia University professor Lorenzo DiTomasso says, by scholars in the 1980s who saw the appeal in an ancient calendar with a defined ending. "A series of cranks got their hands on this stuff, and they essentially unravelled the Mayan calendar – took a circular timeline and gave it a linear ending," he said.
How does the calendar work?
It's complicated. The calendar is actually a series of calenders, wheels within wheels. The calender uses hieroglyphs where we would use numerals.
There is the Calendar Round and the Long Count. The Calendar Round comprises two smaller calendars – the Tzolk'in and the Haab.
The Calendar Round
The Tzolk'in is a 260-day cycle that sets the dates for religious festivals and ceremonies.
There are 20 named periods, each cycling through 13 days.
The Haab is a 365-day, solar-year calendar, divided into 18 months of 20 days each.
The five extra days were considered "unlucky" and made a shorter 19th month.
Consider how the Long Count works as a fancy odometer: It has five slots separated by decimals, using hieroglyphs (where we would use numerals). Basically, Dec. 21, 2012 (approximately) is when almost all the numbers in this cycle of the odometer reach their highest point and they all go back to zero: It will read 188.8.131.52.0.