Vikings could have used sunstones to navigate on cloudy days
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.
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.
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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.
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.