There is no way scientifically they could have known this. Hey, most Westerners thought the world was flat. Remember?
http://www.radiooutthere.com/index.php?option=com_content&task=view&id=34&Itemid=2
Read about what Mayans knew and wonder how they knew. So, I may have to continue doing this until December 21, 2012. Maybe. You never know, or do you always know.
