Sky-Polarimetric Viking Navigation: An Extended Update

In this chapter, we deal with Vikings and the hypothetical sky-polarimetric Viking navigation (SPVN), surveying the knowledge accumulated in the following related topics: Viking sun-compass and sunstones. Atmospheric optical prerequisites of SPVN. Error functions of the four main steps of SPVN. Error propagation in SPVN—navigation accuracy versus sky conditions. Sailing success of SPVN—revealing the chance Vikings could reach Greenland from Norway. Sensitivity and robustness of SPVN. Sailing success of four different Viking navigation methods. Orientation with a Viking sun-compass, a shadow-stick and two calcite sunstones under different sky conditions. Alternative interpretations of the Viking Uunartoq artefact fragment: (i) Instrument to determine latitude and local noon. (ii) Twilight board—how the Viking sun-compass could be used with sunstones before and after sunset? (iii) Atmospheric-optical phenomena as possible alternative navigation cues for Vikings.