Posted on 03/02/2007 10:47:04 AM PST by blam
How Vikings Might Have Navigated on Cloudy Days
By Corey Binns
Special to LiveScience
posted: 02 March 2007
08:33 am ET
Vikings navigated the oceans with sundials aboard their Norse ships. But on an overcast day, sundials would have been useless. Many researchers have suggested that the on foggy days, Vikings looked toward the sky through rock crystals called sunstones to give them direction.
No one had tested the theory until recently.
A team sailed the Arctic Ocean aboard the Swedish icebreaker Oden and found that sunstones could indeed light the way in foggy and cloudy conditions.
Would have worked
Crystals such as cordierite, calcite or turmaline work like polarizing filters, changing in brightness and color as they detect the angle of sunlight. From these changes, Vikings could have accurately determined where the polarized sky light was coming from and pinpointed the direction of the sun, said biophysicist Gabor Horvath.
How it Works
Top images show the Arctic sky on day of (a) fog, (b) sun, and (c) clouds. Images d-f show patterns of the degree of linear polarization. The faint gray line delineates between the sun and the anti-sun. The direction of polarization is perpendicular to the plane of scattering determined by the sun, the observer and the celestial point observed. Readings from two different points in the sky allow one to draw circles passing through these points perpendicularly to the direction of light polarization, and the circles intersect at the sun and anti-sun. The angle of polarization can be seen in images g-i. Credit: G. Horvath/Proceedings of the Royal Society A
(Excerpt) Read more at livescience.com ...
Pretty cool stuff
Or they could have stuck close to land on cloudy days...like they did on most days (sunny or cloudy)
Wonder if I could use the same technique with my polarized sunglasses? (I tend to completely lose my sense of direction on cloudy days. Especially in the Dallas suburbs, where streets are NOT laid out in a grid and tend to run every which way.)
Now that is really, really cool.
My sense of direction in Dallas was laid out on a visit there at night. And it was wrong. I moved to Dallas a couple of weeks later -- it took me years to get it straightened out!!!
Interesting
Here I thought crystals were just for wishful thinking. "For centuries, crystals and other gems have been desired for their alleged magical healing and mystical paranormal powers. This belief continues today among occultists and New Age healers, even though it is based on nothing more than testimonials, the placebo effect, selective thinking, wishful thinking, the Forer effect, sympathetic magic, and communal reinforcement. There is no scientific evidence that crystals are conduits of magical energies useful for healing and protection, or for telling the future."
: 
"An ancient silver coin found in building remains in southern Athens is seen in this undated handout picture provided by the Greek Culture Ministry on Friday, March 2, 2007. Archaeologists have discovered extensive remains of what is believed to be an ancient marketplace with shops and a religious center at the southern edge of Athens. The finds, in the coastal neighborhood of Voula, cover an area of 1,500 square meters (16,000 sq. feet) and date from the 4th or 5th century B.C. the Culture Ministry said Friday." (AP Photo/Greek Culture ministry
This has nothing to do with the Vikings´s method but I believe the Arabs sailed north and south up the coast of India and Africa using the AlKemal (sp) plate. This was a square metal plate with a knotted string at the center. When in sight of land the plate held with the base on the horizon and the moved forward and backward until the North star touched the top of the plate. A knot was tied in the string at the point where it touched the nose to denote that specific headland.
Thereafter, in bad weather or out of sight of land they knew their latitude with reference to the coasts of Africa or India. Of course the seasonal monsoons drove them in the right direction for open ocean trade.
Apparently the Polynesians had a similar method when sailing the huge Pacific. They used the magic gourd. A gourd with two holes in it that represented the latitude of the of the islands in relation to the north star.
Sail south, and on the return find the exact latitude of your islands by using the magic gourd and turn right keeping the north star aligned at arms length with the base on the horizon. Those two holes in your water filled gourd to maintain it level in a moving environment. This way you would know when you moved either north or south of your intended track.
The height of the magician in the boat and the water level also made an artificial horizon. Navigation was one of the dark arts.
I read about these things in a navigation book about 60 years ago which simply explained the principles before all the complexities were discussed. Of course knowledge of Longitude came much later.
Note: this topic is from 3/02/2007. Thanks blam.
I think they found a sunstone in a recent Viking grave. Can’t remember the source though.
I have the Viking gene, I 253, beware.
... or the icepack.
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