Unique crystals could helped the Vikins in sea navigation


According to the legend, special unique crystals, called sunstones could helped the Vikings in sea navigation. A study of Hungarian researchers proved that it was possible to navigate in certain cloudy weather conditions. During the study presented in the current issue of the Proceedings of the Royal Society A scientific journal, Gábor Horváth, the leader of the Environmental Optics Laboratory of the Biological Physics department of the Eötvös Loránd University Faculty of Science (ELTE), the senior author of the study and his colleagues are tested this hypothetical method.

 
Image source: Wikimedia commons/ArniEin

The Vikings traveled thousands of kilometers on the Sea, they even reached North American. They didn't had magnetic compasses, because of this, they navigated based on the position of the Sun. If clouds covered the sky, they located the sun by so-called sunstones, then they determined the north direction.


Image source: Flickr/Geir Are Johansen

In 1967 Thorkild Ramskou Danish archaeologist discovered that the sunstones are crystals working as a polar filter - these were probably Calcite, Tourmaline or Cordierite - and they used them analyse the polarization of the skylight from which the position of the sun covered by clouds is inferable. Gábor and his co-workers are tried with all of the three sunstone crystals in their recently announced study to see how accurate was this 4-step navigation method to determine the route on the sea. To do this they used sky polarization samples measured in 1080 different sky situations. They reached the conclusion that the Calcite are provided more accurate navigation than the other two crystal.

 
Image source: Natural History Museum

When the sky is not covered completely by clouds and the Sun was above the horizon by 35-40 degree angle, the sunstones was the most reliable that time. When the Sun was in the highest point of it's orbit, on the meridian, then practically this kind of navigation was not worked. "This is the first time, when depending on meteorological conditions and sunstone crystals emerged how accurate is the supposed sky polarization Viking navigation in the times of equinox and solstice." - Wrote the Hungarian researchers in the scientific journal.
 
In the Environmental Optics Laboratory of the ELTE with the lead of Gábor Horváth, the study has been running for one and a half decade and they will bring to light with the next step that whether the navigation errors were so small that the Vikings with high possibility was still could reach Greenland or North America in three-four weeks.
 


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