This whole Maya calendar end of the world whoohaa has reached such a pitch that White House.gov for goodness sakes created a link about the idiocy which sends you/me to the answers.USA.gov site with further links to NASA’s point of view on the subject.
Most of the curiosity surrounding the date involves how the ancient Maya civilization viewed time. Archaeological finds revealed that the Maya had a number of highly accurate calendars, including one known as the Long Count calendar. It uses a series of periods (cycles) to count days, months, and years. According to this calendar, a major cycle lasting the equivalent of 394.3 years ends on December 21, 2012. The next cycle begins on December 22, and ends in 2406.
NASA has a tl/dr FAQ that condenses down to:
Nothing bad will happen to the Earth in 2012. Our planet has been getting along just fine for more than 4 billion years, and credible scientists worldwide know of no threat associated with 2012.
But wait! Oh noes! NASA also offers this warning:
Scientists have no way of predicting with perfect accuracy whether a supervolcano will occur in a given century, decade, or year – and that includes 2012. But they do keep close tabs on volcanically active areas around the world, and so far there’s absolutely no sign of a supereruption looming anytime soon.
But fear not!