Archaeologists have found a Viking sunstone in an ancient shipwreck, alongside other navigational implements.
Optics experts at the University of Rennes have examined a white stone found in 2002 during an undersea archaeological investigation. The stone lay amidst the shipwreck for over 400 years, where seawater and sand had roughened its surface and clouded over its light refraction properties.
The English ship sank off the Channel Island of Alderney in the late sixteenth century; documentary evidence suggests a date of 1592, according to the Alderney Maritime Trust.
Viking Sunstone Not a Myth: A Real Navigational Tool
Two factors that marked the stone down as a possible navigation tool were its proximity to a set of navigator’s dividers, and that the angles of the stone’s sides are not right angles, being circa 102º or 78º, rendering its shape rhombohedral. This is typical of spar calcite from Iceland, and speculation began that this could be a sunstone, in Icelandic ‘sólarsteinn’ – long believed to have been a key to Viking navigation, yet never before identified in shipboard archaeological contexts.
“Although crystals used as sun optical compass are mentioned in the saga of Saint Olaf relating to the Viking navigation around the tenth century, no Viking sunstones had yet been discovered, and particularly, none in any way connected with an actual ship.” Le Floch et al say in their 2013 report in the Proceedings of the Royal Society on testing a calcite as an efficient reference optical compass.
The main information about Viking use of the sólarsteinn is scattered through their fables and oral histories, known as sagas, which contain many details of their voyages in the Baltic, conquering northern Europe, and crossing the North Atlantic to North America.
Viking Sagas as Historical Evidence
Sagas were both the entertainment stories and the oral histories of the pre-literate norsemen who originated largely in Denmark and Norway. These poetic stories became written once the culture absorbed Latinate literacy, after their religious conversion to Christianity. Because the texts were written down centuries after the individuals and incidents in them occurred, their historical and scientific accuracy has been treated as unreliable.
Navigation experts such as Leif Karlsen researched the folklore thoroughly, and tested methods suggested in the sagas by applying professional experience. Karlsen’s book, Secrets of the Viking Navigators, was almost ready for press when the Alderney sunstone was found, and he was able to incorporate photographs and diagrams of it.
In the book, Karlsen reports his own experiments testing Viking navigation devices in the light of his forty year career as a ship’s officer. La Floch and other academics have conducted similar tests since the 2002 find.