Hi, humanrevolution! BAUT has a lot of young users, including myself, so you're not alone!
Others here are better than me at astronomy, so I'll explain the archeological side of why this stuff is a load of rotten peanut butter:
The Mayans had several ancient calendars, measuring different lengths of time, like our years, decades, centuries and millenia. When one "turned over", another one began, just like the 21st century began in 2000/2001 when the 20th century ended. The current Long Count calender ends in 2012, but- and this is important- another Long Count calendar cycle starts.
You could call the whole 2012 thing a bit of an ancient version of the Y2K panic!

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"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek
"Carl Sagan sent a message to ET,
Neil Armstrong walked in the Sea of Tranquility
Steve Squyers built Spirit and Opportunity
Dan Haylen upchucked in zero gravity." -Brent Simon, The Space Camp Song