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Continuing my exploration of ancient navigation techniques, I picked up a copy of Secrets of the Viking Navigators the other day. It's not the greatest book in the world (hint: applying photoshop filters to real pictures does not make them look quaint, it just reduces their illustrative value), but it's okay.
One thing that really intrigued me was the talk about viking sunstones. They're mentioned as treasures in certain sagas, but never explained. In 1967 the Danish archaeologist Thorkild Ramskou theorized that they could have been using natural crystals available to them to detect the polarization of the sky. The atmosphere polarizes light passing through it, the more so the greater the angle from the sun. Even if the sun itself is hidden (behind a fog bank, for instance) you can determine its azimuth if you can see any blue sky above you.
Conveniently, the vikings did have a crystal available to them that has polarizing properties: Iceland spar, aka calcite. Thus, claimed this book, that must have been what the sunstones were. Given the slightly dubious vibes I was getting from the book, I figured I would have to try it out myself. One quick ebay transaction later...
( Pictures of ANCIENT VIKING SECRETS )
One thing that really intrigued me was the talk about viking sunstones. They're mentioned as treasures in certain sagas, but never explained. In 1967 the Danish archaeologist Thorkild Ramskou theorized that they could have been using natural crystals available to them to detect the polarization of the sky. The atmosphere polarizes light passing through it, the more so the greater the angle from the sun. Even if the sun itself is hidden (behind a fog bank, for instance) you can determine its azimuth if you can see any blue sky above you.
Conveniently, the vikings did have a crystal available to them that has polarizing properties: Iceland spar, aka calcite. Thus, claimed this book, that must have been what the sunstones were. Given the slightly dubious vibes I was getting from the book, I figured I would have to try it out myself. One quick ebay transaction later...
( Pictures of ANCIENT VIKING SECRETS )