Perhaps the most mysterious structure on Earth, Stonehenge has stood on a plain in Southern England for 5000 years. Why is it there? In this episode we explore the possibility that this was a prehistoric astronomical observatory. Here ancient astronomer priests may have divined the complex movements of the Sun and Moon, recognizing patterns that would not be discovered elsewhere for thousands of years. The primitive Shamans may have also been the first astronomers to predict eclipses.

• Neil deGrasse Tyson
• Erik Thompson
• Alex Filippenko

• David Brin
• David Ackroyd
• Michio Kaku