Overview
There are plenty of great dates for the end of the world. Archbishop James Ussher's infamous count ended on October 23, 1997, at midday. The year 2000 was a focus of millenialism, and had the luck to have its Millennium Bug as a weightier side show. Today's so-called end of the world is a similar, numbers thing.
The Mayans reach an interesting date today, with rumours going around that their version of December 21, 2012 could be a pretty bad day indeed. So many rumours that NASA has set up a page on why we'll all still be around this time tomorrow. They expect no surprise interplanetary collisions, worldwide blackouts or 180 degree polar shifts arriving in the earth's near future.
What is coming is a turned page on the Mayan calendar. The Mayans numbered their years with a calendar system called the Long Count, which started on August 13, 3114BC. For them, that year was 13.0.0.0.0 — 13 baktun (400 years) 0 katun (20 years) 0 years 0 months 0 days. Their creation date started at 13 baktun, but tocked straight from 13.0.0.0.0 back to 1.0.0.0.0, 400 years later. Today the calendar has completed about 5,125 years and is up to 13.0.0.0.0 again, though the evidence seems to suggest that the Maya had no particular plans to start the count again. 400 years from now baktun 14 should arrive, right on schedule.
There are probably very few modern Mayans who think the world is coming to an end. If anything, a Mayan world ended centuries ago: when sixteenth century Conquistadors put an end to much of the mesoamerica's way of life. What's happening today is that we're ticking over from 13.0.0.0.0 to tomorrow's 13.0.0.0.1. The numbers are nice, but tomorrow is bound to look a lot like today.
Leading image of the Aztec calendar stone by El Commandante.