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Message: <blockquote data-quote="Galloglaich" data-source="post: 5062961" data-attributes="member: 77019">Vegvisir The Viking Sun CompassThe Viking Sun Compass " <a href="http://www.enworld.org/w/index.php?title=Hrafns_Saga&action=edit&redlink=1" target="_blank">Hrafns Saga</a> it says: "the weather was thick and stormy . . . The king looked about and saw no blue sky . . . then the king took the sunstone and held it up, and then he saw where [the Sun] beamed from the stone."" <img src="http://fc08.deviantart.net/fs31/f/2008/225/9/f/Brass_Vegvisir__Viking_Compass_by_Vegvisir.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />Modern reconstruction of a Vegvisir, with an embedded cordierite (aka 'iolite') <img src="http://pagesperso-orange.fr/cadrans-solaires/navigation/viking/images/disqciel16_p.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />Illustration of a vegvisir found in a Viking grave in France, 1906   <a href="http://en.wikipedia.org/wiki/Vegv%C3%ADsir#External_links" target="_blank">VegvÃ<img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile    :)"  data-smilie="1"data-shortname=":)" />sir - Wikipedia, the free encyclopedia</a> Vegvísir (<a href="http://www.enworld.org/wiki/Compass" target="_blank">compass</a>) is an <a href="http://www.enworld.org/wiki/Iceland" target="_blank">Icelandic</a> <a href="http://www.enworld.org/wiki/Magic_(paranormal)" target="_blank">magic</a> sign intended to guide people through rough weather. Icelandic singer <a href="http://www.enworld.org/wiki/Bj%C3%B6rk" target="_blank">Björk</a> has it tattooed on her left arm.Vegvisir is not just a myth, however. A disk-like artefact was found in Greenland in 1947 by the archeologist C. L. Vebæk of Denmark. <a href="http://www.enworld.org/forum/#cite_note-Northern_Lights_Planetarium_article-0" target="_blank">[1]</a> A second artifact was found in 2000 at a viking site in Poland <a href="http://www.enworld.org/forum/#cite_note-Robert_Knocks_Johnson_article-1" target="_blank">[2]</a>. After being examined by Captain Sølver and by Søren Thirslund at the Nautical Museum at Kronborg Castle and by professor Curt Roslund at the University of Gøteborg, it was determined to be a 'sun compass'. The disk had different hyperbolas or gnomon curves inscribed upon it, and North is clearly marked with 16 small cuts crossing a long line, dividing the compass in 32 directions (before the magnetic compass had arrived in Europe). Counting the spikes from north and to the right we have 90° or due west, at spike number 8. According to the analysis, the instrument works as follows: the sun´s shadow from the tip in the middle of a disk describes different hyperbolas at different times of the year. The hyperbola represents 62° and the four weeks around summer solstice, you don´t have to know the time of the day in order to find the general directions. All you have to do is rotate the disk until the shadow of the tip falls on the hyperbola, and the general directions are given with an accuracy of a few degrees. One of the ingenious things about navigating with this instrument is that if you should choose the wrong gnomon curve and get a course that is a little too much north in the morning, this will be corrected in the afternoon by a slightly south bound course-and your average direction will be correct.Literary evidence indicates that the vegvisir may have also been used with a 'sunstone' (this was <a href="http://www.enworld.org/wiki/Cordierite" target="_blank">cordierite</a>, not to be confused with the gem <a href="http://www.enworld.org/wiki/Sunstone" target="_blank">sunstone</a>) which polarizes sunlight, allowing the location of the sun to be determiined even in heavy cloud cover, which was common in Northern latitutdes.There was another type of vegvisir which wwas a flat tree-plate with four-five holes in it + a pin of wood approx. 20 cm high and a little wooden'button' which you can move between the holes + a thin rope and a 'sunstone', a crystaal which looks like mica and is thin. Held towards the sun-position it will show light even in cloudy weather or fog. You put the bigger pin in one of the end holes. On top of the pin a thin rope was fastened, and on the rope's other end was a 'tree-button' with which to messure the angle between the horizon and the reflexion point = where the sun is.Minerals Two minerals are possibly associated with the vegvisir. The crystal <a href="http://www.enworld.org/wiki/Cordierite" target="_blank">cordierite</a> can be found as pebbles in the coast of Norway. It has birefringent and dichroic properties, changing color and brightness when rotated in front of polarized light. With an appropiately shaped crystal it is easy to tell the direction of skylight polarization: its color will change (e.g. from blue to light yellow) when pointing towards the sun. The Vikings also coloinzed Iceland, which was the original source of Iceland Spar (<a href="http://www.enworld.org/wiki/Optical_calcite" target="_blank">optical calcite</a>), which has had such an important role in the discovery and study of polarization. Used today for many high-performance polarizers. At high latitude the sun remains for a long time close to the horizon, which produces the best skylight polarization pattern for navigation purposes. Because of perspective, a bank of clouds of uniform density is squeezed together when looking far away. Thus, it is usually much easier to find a clear patch of sky towards the zenith, while crepuscular rays (the beams of light and darkness radiating from the sun when blocked by clouds) are difficult to see close to the zenith, as the line of sight crosses them through their thinnest section. The method would have worked even when the sun was several degrees below the horizon (but still illuminating the atmosphere). Note that at twilight, when the sun is below the horizon by about two degrees, its location is very difficult to ascertain. Although a bright twilight arch can be seen, it occupies a large part of the horizon and is of uniform intensity. A similar effect may conceivable happen when the sun is above the horizon and a thick layer of clouds covers it. Light fog and overcast of thin clouds don't eliminate skylight polarization. The technique has been proven to be effective. A similar instrument was created in the 1950's for use by the US Navy and US Airforce, and several Scandinavian airlines used the Sun Compas for polar flights during much of the second half of the 20th Century.</blockquote>

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