I ran across this Yahoo story this morning:
http://news.yahoo.com/forget-gps-medieval-com...54744.html

I was aware of "sun stones" from some of the literature on Viking navigation but this is one of the better explanations of how it worked. With all the hype surrounding the History Channel's series "The Vikings" - which I am enjoying - it is good to keep in mind that they were pretty smart folks who explored and traded more than they raided.

I also read the article, and refrained from commenting regarding the gap between the Viking Age and the Medieval Age..... same perversity prevents me from enjoying that TV show, I guess after seeing the trailers/previews I cannot watch it
Of course I also was very interested in the sunstones and their accompanying compass. It could be possible that there is no more misunderstood culture than the Norse culture in the present day, so the TV show should not come as a surprise.....