[Rockhounds] Computer simulations show Viking's sunstone to be very accurate

[Kreigh Tomaszewski]

According to a famous hypothesis, Viking sailors could navigate along the
latitude between Norway and Greenland by means of sky polarization in
cloudy weather using a sun compass and sunstone crystals. Using data
measured in earlier atmospheric optical and psychophysical experiments,
here we determine the success rate of this sky-polarimetric Viking
navigation. Simulating 1000 voyages between Norway and Greenland with
varying cloudiness at summer solstice and spring equinox, we revealed the
chance with which Viking sailors could reach Greenland under the varying
weather conditions of a 3-week-long journey as a function of the navigation
periodicity Δt if they analysed sky polarization with calcite, cordierite
or tourmaline sunstones. Examples of voyage routes are also presented. Our
results show that the sky-polarimetric navigation is surprisingly
successful on both days of the spring equinox and summer solstice even
under cloudy conditions if the navigator determined the north direction
periodically at least once in every 3 h, independently of the type of
sunstone used for the analysis of sky polarization. This explains why the
Vikings could rule the Atlantic Ocean for 300 years and could reach North
America without a magnetic compass. Our findings suggest that it is not
only the navigation periodicity in itself that is important for higher
navigation success rates, but also the distribution of times when the
navigation procedure carried out is as symmetrical as possible with respect
to the time point of real noon.

Read more at:
https://phys.org/news/2018-04-simulations-viking-sunstone-accurate.html#jCp