(CNN) -- Just as "Y2K" and its batch of predictions about the year 2000 have become a distant memory, here comes "Twenty-twelve." The sun shines through the door of the Seven Dolls Temple, in the Maya ruins of Dzibilchaltun in Mexico. Fueled by a crop of books, Web sites with countdown clocks, and claims about ancient timekeepers, interest is growing in what some see as the dawn of a new era, and others as an expiration date for Earth: December 21, 2012. The date marks the end of a 5,126-year cycle on the Long Count calendar developed by the Maya, the ancient civilization known for its advanced understanding of astronomy and for the great cities it left behind in Mexico and Central America.
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December 21, 2012, marks the end of a 5,126-year cycle on a Mayan calendar
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Some think the date is ominous, others say it may signal the dawn of a new era
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Theories are fabricated on the basis of very little evidence, Maya scholar says
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"The whole year leading up to it is going to be just crazy," another scholar warns
Theories about what might happen range from solar storms triggering volcano eruptions to a polar reversal that will make the @placeholder spin in the opposite direction.