Mythical Viking Sunstone Used for Navigation was Real and Remarkably Accurate, New Study Shows

Ancient Origins

The Vikings have been reputed to be remarkable seafarers who could fearlessly navigate their way through unknown oceans to invade unsuspecting communities along the North Sea and Atlantic Sea coasts of Europe. A well-known ancient Norse myth describes a magical gem that could reveal the position of the sun when hidden behind clouds or even after sunset. A new study shows the sunstone was real and very accurate.

Several accounts in the ancient Nordic sagas speak of a sólarsteinn or “sunstone”, which they used to determine the sun’s position after sunset. For years, it was thought to be little more than a legend. But in 2010, a unique crystal was found in the wreck of an Elizabethan ship sunk off the coast of the Channel Islands. After three years of intensive study, scientists announced that the crystal made of a calcite substance could indeed act as a navigational aid.

According to those researchers, the principle behind the sunstone relies on its unusual property of creating a double refraction of sunlight, even when it is obscured by cloud or fog. By turning the crystal in front of the human eye until the darkness of the two shadows were equal, the sun's position can be pinpointed with remarkable accuracy.

The Vikings were known to be master seafarers. Leiv Eiriksson Discovers America by Christian Krohg, 1893 ( public domain )

New Study Reveals Accuracy

Phys.org reports on a new study conducted by researchers from ELTE Eötvös Loránd University in Hungary, who ran computer simulations of 1000 voyages between Norway and Greenland with varying cloudiness, in order to determine how accurate the sunstone was in navigation.

“After inputting data describing such trips, the researchers ran the simulations multiple times over the course of two specific virtual days, the spring equinox and the summer solstice. They ran the trials for different types of crystals and with differing intervals between sunstone tests,” reported Phys.org.

The results of their study revealed that using a cordierite crystal for a minimum of every three hours was around 92.2 to 100 percent accurate.

“This explains why the Vikings could rule the Atlantic Ocean for 300 years and could reach North America without a magnetic compass,” the study authors wrote in the paper published by the Royal Society Open Science .

Sunstone was Used in Parallel to a Sun Compass
Researchers believe that they combined the power of the sunstone with that of a sun compass or ‘sundial’ to navigate their ships after dark.

Wooden fragment discovered in Uunartoq, Greenland, in 1948, which is believed to be a sun-compass used to determine direction. Image credit: Soren Thirslund.

Part of a Viking sun compass was unearthed in 1948 in a fjord in Uunartoq, Greeland, which was settled by Norse farmers in the 10 th century. Originally believed to be a household decoration, researchers later discovered that the lines engraved along the edge were for navigational purposes.

“The team found that at noon every day, when the sun is highest in the sky, a dial in the center of the compass would have cast a shadow between two lines on the plate,” reported Live Science in 2013. “The ancient seafarers could have measured the length of that noon shadow using scaling lines on the dial, and then determined the latitude.”

A scene from the Vikings (2013) History Channel Series demonstrates how the sundial was used.

Top image: A calcite crystal found on an Elizabethan ship believed to have helped the Vikings navigate the seas. Credit: The Natural History Museum.

By April Holloway

Archaeologists Uncover Rare 2,000-year-old Roman Sundial and it Tells Them More than Just the Time

Ancient Origins

A 2,000-year-old intact and inscribed sundial – one of only a handful known to have survived – has been recovered during the excavation of a roofed theatre in the Roman town of Interamna Lirenas, near Monte Cassino, in Italy.

 Not only has the sundial survived largely undamaged for more than two millennia, but the presence of two Latin texts means researchers from the University of Cambridge have been able to glean precise information about the man who commissioned it.

The sundial was found lying face down by students of the Faculty of Classics as they were excavating the front of one of the theatre’s entrances along a secondary street. It was probably left behind at a time when the theatre and town was being scavenged for building materials during the Medieval to post-Medieval period. In all likelihood it did not belong to the theatre, but was removed from a prominent spot, possibly on top of a pillar in the nearby forum.

Less than a hundred examples of this specific type of sundial have survived and of those, only a handful bear any kind of inscription at all – so this really is a special find,” said Dr Alessandro Launaro, a lecturer at the Faculty of Classics at Cambridge and a Fellow of Gonville & Caius College.

The sundial pictured after excavation. (Alessandro Launaro)

 “Not only have we been able to identify the individual who commissioned the sundial, we have also been able to determine the specific public office he held in relation to the likely date of the inscription.”

The base prominently features the name of M(arcus) NOVIUS M(arci) F(ilius) TUBULA [Marcus Novius Tubula, son of Marcus], whilst the engraving on the curved rim of the dial surface records that he held the office of TR(ibunus) PL(ebis) [Plebeian Tribune] and paid for the sundial D(e) S(ua) PEC(unia) (with his own money).

The nomen Novius was quite common in Central Italy. On the other hand, the cognomen Tubula (literally ‘small trumpet’) is only attested at Interamna Lirenas.

Image of Roman Plebeians. (serenitynaturalwellness)

But even more striking is the specific public office Tubula held in relation to the likely date of the inscription. Various considerations about the name of the individual and the lettering style comfortably place the sundial’s inscription at a time (mid 1st c. BC onwards) by which the inhabitants of Interamna had already been granted full Roman citizenship.

“That being the case, Marcus Novius Tubula, hailing from Interamna Lirenas, would be a hitherto unknown Plebeian Tribune of Rome,” added Launaro. “The sundial would have represented his way of celebrating his election in his own hometown.”

Roman sundial (Interamna Lirenas, Italy) by al506 on Sketchfab

Carved out from a limestone block (54 x 35 x 25 cm), the sundial features a concave face, engraved with 11 hour lines (demarcating the twelve horae of daylight) intersecting three day curves (giving an indication of the season with respect to the time of the winter solstice, equinox and summer solstice). Although the iron gnomon (the needle casting the shadow) is essentially lost, part of it is still preserved under the surviving lead fixing. This type of ‘spherical’ sundial was relatively common in the Roman period and was known as hemicyclium.

“Even though the recent archaeological fieldwork has profoundly affected our understanding of Interamna Lirenas, dispelling long-held views about its precocious decline and considerable marginality, this was not a town of remarkable prestige or notable influence,” added Launaro. “It remained an average, middle-sized settlement, and this is exactly what makes it a potentially very informative case study about conditions in the majority of Roman cities in Italy at the time”.

Artist’s reconstruction of life in a Roman cardo of Jerusalem during the Aelia Capitolina period. (Carole Raddato/CC BY SA 2.0)

 “In this sense, the discovery of the inscribed sundial not only casts new light on the place Interamna Lirenas occupied within a broader network of political relationships across Roman Italy, but it is also a more general indicator of the level of involvement in Rome’s own affairs that individuals hailing from this and other relatively secondary communities could aspire to.”

The ongoing archaeological project at Interamna Lirenas continues to add new evidence about important aspects of the Roman civilization, stressing the high levels of connectivity and integration (political, social, economic and cultural) which it featured.

The find spot near the former roofed theatre in Interamna Lirenas. (CC BY 4.0)

The 2017 excavation, directed by Dr Launaro (Gonville & Caius College) and Professor Martin Millett (Fitzwilliam College), both from the Faculty of Classics, in partnership with Dr Giovanna Rita Bellini of the Italian Soprintendenza Archeologia, Belle Arti e Paesaggio per le Province di Frosinone, Latina e Rieti, is part of a long-standing collaboration with the British School at Rome and the Comune of Pignataro Interamna and has benefitted from the generous support of the Isaac Newton Trust and Mr Antonio Silvestro Evangelista.

Top Image: The Roman sundial. Source: Cambridge University

The article, originally titled ‘Archaeologists uncover rare 2,000-year-old sundial during Roman theatre excavation’, was originally published on University of Cambridge and has been republished under a Creative Commons license.