How the Vikings were able to navigate the oceans in the fog using the first polarisation technology

Many centuries ago the Vikings were able to navigate a large part of the globe, even though on the northern seas the position of the sun was often impossible to measure because of clouds and fog. Legends tell of a Viking "sun stone" that would act as a compass. We now know that this sun stone is in fact a device to measure the sky polarisation, which contains all the information one would need to find directions.