On July 15, 2008, a crop circle appeared on Avebury Manor (pictured) near the town of Avebury in England, which is also the site of a megalithic stone circle. It is a representation of our solar system and where the planets will be on Dec. 21-23, 2012. Just one week later, an addition to the existing crop circle and another one beside it appeared. It's clear these are references to 2012 and have provoked a cottage industry of interpretations: Nibiru, comets, and a solar conflagration are some of the ideas. These are, perhaps, some of the most interesting crop circles ever. A very concise interpretation is nicely done in a brief three minute video linked: here. It's pretty amazing stuff!